papers.sim2.be

ReviewContinuous ultrasonic reactors: design, mechanism and applicationZhengya Dong ?, Claire Delacour, ?, Keiran Mc Carogher ?, Aniket Pradip Udepurkar and Simon Kuhn *Department of Chemical Engineering, KU post code Leuven, Leuven, Belgium; zhengya.dong@kuleuven.be (Z.D.); claire.delacour@kuleuven.be (C.D.); keiran.mccarogher@kuleuven.be (K.M.); aniketpradip.udepurkar@kuleuven.be (A.U.)*Correspondence: simon.kuhn@kuleuven.be?These authors contributed equallyReceived: 16 December 2019; 8 January 2020; Published: dateAbstract: Ultrasonic small scale flow reactors have found increasing popularity among researchers as they serve as a very useful platform for studying and controlling ultrasound mechanisms and effects. This has led to the use of these reactors for not only research purposes, but also various applications in biological, pharmaceutical and chemical processes mostly on laboratory and, in some cases, pilot scale. This review summarizes the state of the art of ultrasonic flow reactors and provides a guideline towards their design, characterization, and application. Particular examples for ultrasound enhanced multiphase processes, spanning from immiscible fluid–-fluid to fluid–-solid systems, are provided. To conclude, challenges such as reactor efficiency and scalability are addressed.Keywords: microfluidics; ultrasound; process intensification; sonochemistry; flow chemistry1. IntroductionSmall scale flow reactors, namely micro and milli-reactors, have great advantages over conventional reactors, such as well-controlled flow patterns and increased surface-to-volume ratios, resulting in enhanced heat and mass transfer rates ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/anie.200300577","ISSN":"14337851","abstract":"The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process-engineering-oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature-induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid-phase, gas-phase, and gas-liquid reactions.","author":[{"dropping-particle":"","family":"J?hnisch","given":"Klaus","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hessel","given":"Volker","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"L?we","given":"Holger","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Baerns","given":"Manfred","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Angewandte Chemie - International Edition","id":"ITEM-1","issued":{"date-parts":[["2004"]]},"page":"406-446","title":"Chemistry in Microstructured Reactors","type":"article-journal","volume":"43"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/aic.15642","abstract":"Over the past two decades, microreaction technology has matured from early devices and concepts to encompass a wide range ofcommercial equipment and applications. This evolution has been aided by the confluence ofmicroreactor develop- ment and adoption of continuous flow technology in organic chemistry. This Perspective summarizes the current state-of- the art with focus on enabling technologies for reaction and separation equipment. Automation and optimization are highlighted as promising applications ofmicroreactor technology. The move towards continuous processing in pharmaceu- tical manufacturing underscores increasing industrial interest in the technology. As an example, end-to-end fabrication of pharmaceuticals in a compact reconfigurable system illustrates the development of on-demand manufacturing units based on microreactors. The final section provides an outlook for the technology, including implementation challenges and inte- gration with computational tools.","author":[{"dropping-particle":"","family":"Jensen","given":"Klavs F","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-2","issue":"3","issued":{"date-parts":[["2017"]]},"page":"858-869","title":"Flow Chemistry — Microreaction Technology Comes of Age","type":"article-journal","volume":"63"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1021/op5001918","abstract":"A toolbox approach for the transfer of batch to continuous chemical synthesis is presented. The approach considers reaction kinetics (Type A, B, C), reacting phases (single phase, liquid?liquid, gas?liquid and liquid?solid), and the reaction network (parallel and consecutive reactions) in order to select the most appropriate reactor module (Plate, Coil, or CSTR) for continuous operation. Then, three case studies using these three fundamental reactors are presented but require special considerations. For the reaction of dimethyl-oxalate with ethylmagnesium chloride, a plug-flow multi-injection technology must be used to decrease the local heat generation and improve yield. For the nitration of salicylic acid, a Plate reactor with mixing elements favoring some back-mixing followed by a plug-flow system at elevated temperatures is used instead of a tandem mixed-flow CSTR and plug-flow Coil reactor in order to minimize the risk of thermal decomposition of intermediates with a reduced volume penalty. Finally, a ring-closing metathesis reaction is discussed for which the utilization of a CSTR allows the removal of catalyst-poisoning ethylene formed during the reaction and keeps the substrate concentration low to increase the yield above that of a batch or plug-flow system.","author":[{"dropping-particle":"","family":"Plou","given":"Patrick","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Macchi","given":"Arturo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Roberge","given":"Dominique M","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research & Development","id":"ITEM-3","issued":{"date-parts":[["2014"]]},"page":"1286-1294","title":"From Batch to Continuous Chemical Synthesis  A Toolbox Approach","type":"article-journal","volume":"18"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1002/ceat.201100643","ISBN":"09307516","ISSN":"09307516","PMID":"23641116","abstract":"Over the last ten to fifteen years, microreaction technology has become of increased interest to both academics and industrialists for intensification of multiphase processes. Amongst the vast application possibilities, fast, highly exothermic and/or mass transfer-limited gas-liquid reactions benefit from process miniaturization. Recent studies of hydrodynamics and mass transfer in gas-liquid microreactors with closed and open microchannels, e.g., falling-film microreactors, are reviewed and compared. Special attention is paid to Taylor or slug flow in closed channels, as this regime seems to be most adapted for practical engineering applications.","author":[{"dropping-particle":"","family":"Sobieszuk","given":"Pawel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Aubin","given":"Jo?lle","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pohorecki","given":"Ryszard","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Technology","id":"ITEM-4","issue":"8","issued":{"date-parts":[["2012"]]},"page":"1346-1358","title":"Hydrodynamics and mass transfer in gas-liquid flows in microreactors","type":"article-journal","volume":"35"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1002/cssc.201000271","ISSN":"1864564X","abstract":"Several features that allow flow microreactors contribute to green and sustainable chemical synthesis are presented: (1) For extremely fast reactions, kinetics often cannot be used because of the lack of homogeneity of the reaction environment when they are conducted in batch macroreactors. Better controllability, by virtue of fast mixing based on short diffusion paths in microreactors, however, leads to a higher selectivity of the products, based on kinetics considerations. Therefore, less waste is produced. (2) Reactions involving highly unstable intermediates usually require very low temperatures when they are conducted in macrobatch reactors. By virtue of short residence times, flow microreactors enable performing such reactions at ambient temperatures, avoiding cryogenic conditions and minimizing the energy required for cooling. (3) By virtue of the precise residence time control, flow microreactors allow to avoid the use of auxiliary substances such as protecting groups, enabling highly atom- and step-economical straightforward syntheses. The development of several test plants based on microreaction technology has proved that flow microreactor synthesis can be applied to the green and sustainable production of chemical substances on industrial scales. (4) Microreactor technology enables on-demand and on-site synthesis, which leads to less energy for transportation and easy recycling of substances. ? 2011 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim.","author":[{"dropping-particle":"","family":"Yoshida","given":"Jun Ichi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kim","given":"Heejin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nagaki","given":"Aiichiro","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-5","issued":{"date-parts":[["2011"]]},"page":"331-340","title":"Green and Sustainable Chemical Synthesis Using Flow Microreactors","type":"article-journal","volume":"4"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1038/nchem.1753","ISSN":"17554330","abstract":"The past two decades have seen far-reaching progress in the development of microfluidic systems for use in the chemical and biological sciences. Here we assess the utility of microfluidic reactor technology as a tool in chemical synthesis in both academic research and industrial applications. We highlight the successes and failures of past research in the field and provide a catalogue of chemistries performed in a microfluidic reactor. We then assess the current roadblocks hindering the widespread use of microfluidic reactors from the perspectives of both synthetic chemistry and industrial application. Finally, we set out seven challenges that we hope will inspire future research in this field. ? 2013 Macmillan Publishers Limited. All rights reserved.","author":[{"dropping-particle":"","family":"Elvira","given":"Katherine S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"I Solvas","given":"Xavier Casadevall","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wootton","given":"Robert C.R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Demello","given":"Andrew J.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Nature Chemistry","id":"ITEM-6","issue":"11","issued":{"date-parts":[["2013"]]},"page":"905-915","title":"The past, present and potential for microfluidic reactor technology in chemical synthesis","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[1–6]","plainTextFormattedCitation":"[1–6]","previouslyFormattedCitation":"[1–6]"},"properties":{"noteIndex":0},"schema":""}[1–6]. Coupled with other benefits such as inherent safety allowing to perform reactions at elevated temperatures, pressures, or using highly reactive intermediates, they have become an attractive choice for the continuous manufacturing of chemicals and pharmaceuticals ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/cssc.201200766","ISSN":"1864564X","abstract":"Novel Process Windows make use of process conditions that are far from conventional practices. This involves the use of high temperatures, high pressures, high concentrations (solvent-free), new chemical transformations, explosive conditions, and process simplification and integration to boost synthetic chemistry on both the laboratory and production scale. Such harsh reaction conditions can be safely reached in microstructured reactors due to their excellent transport intensification properties. This Review discusses the different routes towards Novel Process Windows and provides several examples for each route grouped into different classes of chemical and process-design intensification. ? 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.","author":[{"dropping-particle":"","family":"Hessel","given":"Volker","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"Dana","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kockmann","given":"Norbert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wang","given":"Qi","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-1","issued":{"date-parts":[["2013"]]},"page":"746-789","title":"Novel process windows for enabling, accelerating, and uplifting flow chemistry","type":"article","volume":"6"},"uris":[""]},{"id":"ITEM-2","itemData":{"abstract":"Advances in drug potency and tailored therapeutics are promoting pharmaceutical manufacturing to transition from a traditional batch paradigm to more flexible continuous processing. Here we report the development of a multistep continuous-flow CGMP (current good manufacturing practices) process that produced 24 kilograms of prexasertib monolactate monohydrate suitable for use in human clinical trials. Eight continuous unit operations were conducted to produce the target at roughly 3 kilograms per day using small continuous reactors, extractors, evaporators, crystallizers, and filters in laboratory fume hoods. Success was enabled by advances in chemistry, engineering, analytical science, process modeling, and equipment design. Substantial technical and business drivers were identified, which merited the continuous process. The continuous process afforded improved performance and safety relative to batch processes and also improved containment of a highly potent compound. A","author":[{"dropping-particle":"","family":"Cole","given":"Kevin P","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Groh","given":"Jennifer Mcclary","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Johnson","given":"Martin D","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Burcham","given":"Christopher L","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Campbell","given":"Bradley M","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Diseroad","given":"William D","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heller","given":"Michael R","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Howell","given":"John R","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kallman","given":"Neil J","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Koenig","given":"Thomas M","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"May","given":"Scott A","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Miller","given":"Richard D","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mitchell","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Myers","given":"David P","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Myers","given":"Steven S","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Phillips","given":"Joseph L","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Polster","given":"Christopher S","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"White","given":"Timothy D","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cashman","given":"Jim","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hurley","given":"Declan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Moylan","given":"Robert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sheehan","given":"Paul","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Spencer","given":"Richard D","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Desmond","given":"Kenneth","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Desmond","given":"Paul","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gowran","given":"Olivia","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Science","id":"ITEM-2","issued":{"date-parts":[["2017"]]},"page":"1144-1150","title":"Kilogram-scale prexasertib monolactate monohydrate synthesis under continuous-flow CGMP conditions","type":"article-journal","volume":"356"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1002/cite.201500028","abstract":"Small-scale, continuous-flow processes are currently discussed in the chemical industry for rapid process development and manufacturing of small product amounts. This contribution describes an equipment toolbox system for continuously operated chemical reactors consisting of microfluidic chip or plate reactors for rapid mixing, capillary or coil tube reac- tors for defined mixing and residence time, as well as continuously stirred tank reactors. The involved phases of the physico-chemical system determine the successfully deployed elements or modules and therefore enable the setup of a flexible multipurpose plant. The platform strategy with modules of similar flow throughput as well as temperature or pressure range allow for consistent scale-up. Several exam- ples show the current development level, while first experiences from plant engineering indicate the implementation status and open issues.","author":[{"dropping-particle":"","family":"Kockmann","given":"Norbert","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemBioEng Rev","id":"ITEM-3","issue":"1","issued":{"date-parts":[["2016"]]},"page":"1-12","title":"Modular Equipment for Chemical Process Development and Small-Scale Production in Multipurpose Plants","type":"article-journal","volume":"3"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.cogsc.2017.06.003","ISSN":"24522236","abstract":"Enhanced heat and mass transfer, precise residence time control, shorter process times, increased safety, reproducibility, better product quality and easy scalability are just a few of the advantages of flow chemistry and reason for the increasing implementation of continuous processes not only in academia but also into the fine chemical manufacturing sector. Notably, to make a process greener and more sustainable becomes eminently important when going from lab-scale to production scale. In this review, the question to which extent continuous flow processing has an impact as green technology, in particular on the synthesis of active pharmaceutical ingredients (APIs) on manufacturing scale, is discussed. Based on the principles of both green chemistry and green engineering selected continuous processes are evaluated.","author":[{"dropping-particle":"","family":"Dallinger","given":"Doris","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kappe","given":"C. Oliver","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Current Opinion in Green and Sustainable Chemistry","id":"ITEM-4","issued":{"date-parts":[["2017"]]},"page":"6-12","publisher":"Elsevier B.V.","title":"Why flow means green – Evaluating the merits of continuous processing in the context of sustainability","type":"article-journal","volume":"7"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1039/c9gc00773c","abstract":"Continuous manufacturing and Green Chemistry, are two promising approaches to synthesis with under- utilized potential that are gaining traction by the wider pharmaceutical community. We review Green Chemistry advances resulting when transitioning to continuous manufacturing with focus on Green Chemistry elements inherent in flow chemistry and related separation processes. Case studies of continu- ous manufacturing represented by the F3 (Flexible, Fast, and Future) project, cGPM manufacturing at Eli Lilly, and the MIT pharmaceuticals on demand projects provide examples of Green Chemistry advances realised. Throughout the review, Green Chemistry advances are identified in terms of the pertinent prin- ciples of Green Chemistry. A count of the occurrences of the different principles of Green Chemistry reveals that the principle of prevention greatly overshadows all other principles. Introduction","author":[{"dropping-particle":"","family":"Rogers","given":"Luke","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Green Chemistry","id":"ITEM-5","issued":{"date-parts":[["2019"]]},"page":"3481-3498","publisher":"Royal Society of Chemistry","title":"Continuous manufacturing – the Green Chemistry promise ?","type":"article-journal","volume":"21"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1126/science.aaf1337","ISSN":"10959203","PMID":"27034366","abstract":"Pharmaceutical manufacturing typically uses batch processing at multiple locations. Disadvantages of this approach include long production times and the potential for supply chain disruptions. As a preliminary demonstration of an alternative approach, we report here the continuous-flow synthesis and formulation of active pharmaceutical ingredients in a compact, reconfigurable manufacturing platform. Continuous end-to-end synthesis in the refrigerator-sized [1.0 meter (width) × 0.7 meter (length) × 1.8 meter (height)] system produces sufficient quantities per day to supply hundreds to thousands of oral or topical liquid doses of diphenhydramine hydrochloride, lidocaine hydrochloride, diazepam, and fluoxetine hydrochloride that meet U.S. Pharmacopeia standards. Underlying this flexible plug-and-play approach are substantial enabling advances in continuous-flow synthesis, complex multistep sequence telescoping, reaction engineering equipment, and real-time formulation.","author":[{"dropping-particle":"","family":"Adamo","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Beingessner","given":"Rachel L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Behnam","given":"Mohsen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamison","given":"Timothy F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Monbaliu","given":"Jean Christophe M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Myerson","given":"Allan S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Revalor","given":"Eve M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Snead","given":"David R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stelzer","given":"Torsten","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Weeranoppanant","given":"Nopphon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wong","given":"Shin Yee","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Ping","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Science","id":"ITEM-6","issue":"6281","issued":{"date-parts":[["2016"]]},"page":"61-67","title":"On-demand continuous-flow production of pharmaceuticals in a compact, reconfigurable system","type":"article-journal","volume":"352"},"uris":[""]}],"mendeley":{"formattedCitation":"[7–12]","plainTextFormattedCitation":"[7–12]","previouslyFormattedCitation":"[7–12]"},"properties":{"noteIndex":0},"schema":""}[7–12]. However, these appealing applications are still hindered by two important problems namely, weak convective mixing and issues regarding solid handling ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Wu","given":"Kejun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chimica Oggi/Chemistry Today","id":"ITEM-1","issue":"3","issued":{"date-parts":[["2014"]]},"page":"62-67","title":"Strategies for solids handling in microreactors","type":"article-journal","volume":"32"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c4cc07849g","ISSN":"1364548X","abstract":"This work reviews efforts in the greatest challenge to operate microsystems: fouling and blocking.Microstructured devices are widely used for manufacturing products that benefit from process intensification, with pharmaceutical products or specialties of the chemical industry being prime examples. These devices are ideally used for processing pure fluids. Where particulate or non-pure flows are involved, processes are treated with utmost caution since related fouling and blocking issues present the greatest barrier to operating microstructured devices effectively. Micro process engineering is a relatively new research field and there is limited understanding of fouling in these dimensions and its underlying processes and phenomena. A comprehensive review on fouling in microstructured devices would be helpful in this regard, but is currently lacking. This paper attempts to review recent developments of fouling in micro dimensions for all fouling categories (crystallization, particulate, chemical reaction, corrosion and biological growth fouling) and the sequential events involved (initiation, transport, attachment, removal and aging). Compared to fouling in macro dimensions, an additional sixth category is suggested: clogging by gas bubbles. Most of the reviewed papers present very specific fouling investigations making it difficult to derive general rules and parameter dependencies, and comparative or critical considerations of the studies were difficult. We therefore used a statistical approach to evaluate the research in the field of fouling in microchannels.","author":[{"dropping-particle":"","family":"Schoenitz","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Grundemann","given":"Laura","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Augustin","given":"Wolfgang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Scholl","given":"Stephan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Communications","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"8213-8228","publisher":"Royal Society of Chemistry","title":"Fouling in microstructured devices: a review","type":"article-journal","volume":"51"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1021/op100154d","ISSN":"10836160","abstract":"We investigate the mechanisms that govern plugging in microreactors during Pd-catalyzed amination reactions. Both bridging and constriction were shown to be important mechanisms that lead to clogging in our system and greatly limited the utility of microsystems for this class of reactions. On the basis of these observations, several approaches were engineered to overcome the challenge of plugging and to enable the continuous-flow synthesis of a biarylamine. Bridging could be eliminated with acoustic irradiation while constriction was managed via fluid velocity and the prediction of growth rates. ? 2010 American Chemical Society.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-3","issued":{"date-parts":[["2010"]]},"page":"1347-1357","title":"Overcoming the challenges of solid bridging and constriction during Pd-catalyzed C-N bond formation in microreactors","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1103/PhysRevE.74.061402","ISSN":"15393755","abstract":"We investigate clogging of microchannels at the single-pore level using microfluidic devices as model porous media. The process of clogging is studied at low volume fractions and high flow rates, a technologically important regime. We show that clogging is independent of particle flow rate and volume fraction, indicating that collective effects do not play an important role. Instead, the average number of particles that can pass through a pore before it clogs scales with the ratio of pore to particle size. We present a simple model that accounts for the data.","author":[{"dropping-particle":"","family":"Wyss","given":"Hans M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Blair","given":"Daniel L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Morris","given":"Jeffrey F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stone","given":"Howard A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Weitz","given":"David A.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Physical Review E","id":"ITEM-4","issue":"061402","issued":{"date-parts":[["2006"]]},"note":"From Duplicate 2 (Mechanism for clogging of microchannels - Wyss, Hans M.; Blair, Daniel L.; Morris, Jeffrey F.; Stone, Howard A.; Weitz, David A.)\n\nstudy of the clogging of microchannels. Study of the process of clogging at low volume fractions and high flow rates","page":"1-4","title":"Mechanism for clogging of microchannels","type":"article-journal","volume":"74"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1039/C6SM01879C","ISBN":"1842-6573","ISSN":"1744-683X","PMID":"24173598","abstract":"The transport of suspensions of microparticles in confined environments is associated with complex phenomena at the interface of fluid mechanics and soft matter. Indeed, the deposition and assembly of particles under flow involve hydrodynamic, steric and colloidal forces, and can lead to the clogging of microchannels. The formation of clogs dramatically alters the performance of both natural and engineered systems, effectively limiting the use of microfluidic technology. While the fouling of porous filters has been studied at the macroscopic level, it is only recently that the formation of clogs has been considered at the pore-scale, using microfluidic devices. In this review, we present the clogging mechanisms recently reported for suspension flows of colloidal particles and for biofluids in microfluidic channels, including sieving, bridging and aggregation of particles. We discuss the technological implications of the clogging of microchannels and the schemes that leverage the formation of clogs. We finally consider some of the outstanding challenges involving clogging in human health, which could be tackled with microfluidic methods.","author":[{"dropping-particle":"","family":"Dressaire","given":"Emilie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sauret","given":"Alban","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Soft Matter","id":"ITEM-5","issued":{"date-parts":[["2017"]]},"page":"37-48","publisher":"Royal Society of Chemistry","title":"Clogging of microfluidic systems","type":"article-journal","volume":"13"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1002/ceat.200407128","abstract":"50% of reactions in the fine chemical/pharmaceutical industry could benefit from a continuous process based mainly on microreactor technology. However, the frequent presence of a solid phase still hinders the widespread application of such a technology as a multi-purpose solution. For small scale and pilot productions, speed in process R&D, as well as the avoidance of scale-up issues, are the main drivers. On the other hand, for large scale productions, a gain in yield and safety are the main motivations for the use of micoreactor technology. The gain in yield must be significant in order to cope with the increase in capital expenditure associated with the development of a new technology.","author":[{"dropping-particle":"","family":"Roberge","given":"Dominique M","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ducry","given":"Laurent","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bieler","given":"Nikolaus","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cretton","given":"Philippe","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zimmermann","given":"Bertin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chem. Eng. Technol","id":"ITEM-6","issue":"3","issued":{"date-parts":[["2005"]]},"page":"318-323","title":"Microreactor Technology : A Revolution for the Fine Chemical and Pharmaceutical Industries ?","type":"article-journal","volume":"28"},"uris":[""]},{"id":"ITEM-7","itemData":{"DOI":"10.1021/op200348t","ISSN":"10836160","abstract":"The management of solid compounds is a major challenge facing the upstream, continuous processing of pharmaceuticals and fine chemicals. Many reactions relevant to fine chemical production either react with or form insoluble materials, which become problematic in continuous flow microreactors. The deposition, growth, or bridging of compounds can limit fluid flow from the micro-to the mesoscale, and thereby render continuous reactors inoperable. A comprehensive approach for managing solids consists of solids identification, the development of the root failure mechanism(s), and the application of active and passive techniques for the prevention and remediation. This review examines the basic principles of microreactor design for reactions that involve solids, toward the goal of performing the continuous flow processing of fine chemicals.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-7","issued":{"date-parts":[["2012"]]},"note":"Liquid-solid, clogging mechanism prevention","page":"870-887","title":"Managing Solids in Microreactors for the Upstream Continuous Processing of Fine Chemicals","type":"article-journal","volume":"16"},"uris":[""]},{"id":"ITEM-8","itemData":{"DOI":"10.1016/j.cis.2012.10.001","ISSN":"00018686","abstract":"Particulate fouling generally arises from the continuous deposition of colloidal particles on initially clean surfaces, a process which can even lead to a complete blockage of the fluid cross-section. In the present paper, the initial stages of the fouling process (which include single-particle deposition and reentrainment) are first addressed and current modelling state-of-the-art for particle-turbulence and particle-wall interactions is presented. Then, attention is specifically focused on the later stages (which include multilayer formation, clogging and blockage). A detailed review of experimental works brings out the essential mechanisms occurring during these later stages: as for the initial stages, it is found that clogging results from the competition between particle-fluid, particle-surface and particle-particle interactions. Numerical models that have been proposed to reproduce the later stages of fouling are then assessed and a new Lagrangian stochastic approach to clogging in industrial cases is detailed. These models further confirm that, depending on hydrodynamical conditions (the flow velocity), fluid characteristics (such as the ionic strength) as well as particle and substrate properties (such as zeta potentials), particle deposition can lead to the formation of either a single monolayer or multilayers. The present paper outlines also future numerical developments and experimental works that are needed to complete our understanding of the later stages of the fouling process. ? 2012 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Henry","given":"Christophe","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Minier","given":"Jean Pierre","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lefèvre","given":"Grégory","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Advances in Colloid and Interface Science","id":"ITEM-8","issued":{"date-parts":[["2012"]]},"note":"Clogging Mechanism","page":"34-76","publisher":"Elsevier B.V.","title":"Towards a description of particulate fouling: From single particle deposition to clogging","type":"article-journal","volume":"185-186"},"uris":[""]}],"mendeley":{"formattedCitation":"[13–20]","plainTextFormattedCitation":"[13–20]","previouslyFormattedCitation":"[13–20]"},"properties":{"noteIndex":0},"schema":""}[13–20]. Weak convective mixing can be avoided with the use of passive mixing structures (such as bends, necks and baffles), however these structures make reactors more susceptible to clogging ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ces.2004.11.033","ISSN":"00092509","abstract":"A review on microstructured mixer devices and their mixing principles concerning miscible liquids (and gases) is given. This is supplemented by the description of typical mixing element designs, methods for mixing characterisation, and application fields. The mixing principles applied can be divided in two classes relying either on the pumping energy or provision of other external energy to achieve mixing, termed passive and active mixing, respectively. As far as passive mixing is concerned, devices and techniques such as Y- and T-type flow-, multi-laminating-, split-and-recombine-, chaotic-, jet colliding-, recirculation flow-mixers and others are discussed. Active mixing can be accomplished by time-pulsing flow owing to a periodical change of pumping energy or electrical fields, acoustic fluid shaking, ultrasound, electrowetting-based droplet shaking, microstirrers, and others. ? 2005 Elsevier Ltd. All rights reserved.","author":[{"dropping-particle":"","family":"Hessel","given":"Volker","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"L?we","given":"Holger","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sch?nfeld","given":"Friedhelm","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-1","issued":{"date-parts":[["2005"]]},"page":"2479-2501","title":"Micromixers - A review on passive and active mixing principles","type":"article-journal","volume":"60"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/9783527685226","author":[{"dropping-particle":"","family":"Kashid","given":"Madhvanand N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Renken","given":"Albert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kiwi-Minsker","given":"Lioubov","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-2","issued":{"date-parts":[["2014"]]},"publisher":"Wiley","title":"Microstructured Devices for Chemical Processing","type":"book"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/c6lc00728g","ISSN":"1473-0197","abstract":"Continuous multiphase flow strategies are commonly employed for high-throughput parameter screening of physical, chemical, and biological processes as well as continuous preparation of a wide range of fine chemicals and micro/nano particles with processing times up to 10 min. The inter-dependency of mixing and residence times, and their direct correlation with reactor length have limited the adaptation of multiphase flow strategies for studies of processes with relatively long processing times (0.5–24 h). In this frontier article, we describe an oscillatory multiphase flow strategy to decouple mixing and residence times and enable investigation of longer timescale experiments than typically feasible with conventional continu- ous multiphase flow approaches. We review current oscillatory multiphase flow technologies, provide an overview of the advancements of this relatively new strategy in chemistry and biology, and close with a perspective on future opportunities. Introduction","author":[{"dropping-particle":"","family":"Abolhasani","given":"Milad","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2016"]]},"page":"2775-2784","publisher":"Royal Society of Chemistry","title":"Oscillatory multiphase flow strategy for chemistry and biology","type":"article-journal","volume":"16"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-4","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1021/acs.oprd.6b00359","ISSN":"1520586X","abstract":"The increasing academic and industrial interest in flow chemistry resulted in the development of various micro- and milliflow reactors for a wide range of reactions. Owing to this variety in flow reactors, it is vital to select the correct type benefiting the considered chemical reaction. This decision can be based on two fundamental reactor characterization techniques, namely, the residence time distribution (RTD) and the Villermaux?Dushman protocol. The first technique highlights deviations from ideal plug flow, while the latter is a reaction based characterization technique to quantify the efficiency of micromixing. This paper compares the performance of classical tube reactors with internal diameters ranging from 0.4 to 4.8 mm and commercial chip reactors from Little Things Factory and Chemtrix (KiloFlow and Labtrix). The reactor characterization serves as an aid for the reaction selection, dependent on the kinetics of the studied reaction. The suitability of a reactor for very fast reactions (reaction half-life <1 s) or fast reactions (reaction time 1 s to 10 min) is discussed.","author":[{"dropping-particle":"","family":"Gobert","given":"Sven R.L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Thomassen","given":"Leen C.J.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-5","issue":"4","issued":{"date-parts":[["2017"]]},"page":"531-542","title":"Characterization of Milli- and Microflow Reactors: Mixing Efficiency and Residence Time Distribution","type":"article-journal","volume":"21"},"uris":[""]}],"mendeley":{"formattedCitation":"[21–25]","plainTextFormattedCitation":"[21–25]","previouslyFormattedCitation":"[21–25]"},"properties":{"noteIndex":0},"schema":""}[21–25].Integrating ultrasound with small scale flow reactors has proven to be one of the more promising method to address clogging and mixing issues ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Wu","given":"Kejun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chimica Oggi/Chemistry Today","id":"ITEM-1","issue":"3","issued":{"date-parts":[["2014"]]},"page":"62-67","title":"Strategies for solids handling in microreactors","type":"article-journal","volume":"32"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c4cc07849g","ISSN":"1364548X","abstract":"This work reviews efforts in the greatest challenge to operate microsystems: fouling and blocking.Microstructured devices are widely used for manufacturing products that benefit from process intensification, with pharmaceutical products or specialties of the chemical industry being prime examples. These devices are ideally used for processing pure fluids. Where particulate or non-pure flows are involved, processes are treated with utmost caution since related fouling and blocking issues present the greatest barrier to operating microstructured devices effectively. Micro process engineering is a relatively new research field and there is limited understanding of fouling in these dimensions and its underlying processes and phenomena. A comprehensive review on fouling in microstructured devices would be helpful in this regard, but is currently lacking. This paper attempts to review recent developments of fouling in micro dimensions for all fouling categories (crystallization, particulate, chemical reaction, corrosion and biological growth fouling) and the sequential events involved (initiation, transport, attachment, removal and aging). Compared to fouling in macro dimensions, an additional sixth category is suggested: clogging by gas bubbles. Most of the reviewed papers present very specific fouling investigations making it difficult to derive general rules and parameter dependencies, and comparative or critical considerations of the studies were difficult. We therefore used a statistical approach to evaluate the research in the field of fouling in microchannels.","author":[{"dropping-particle":"","family":"Schoenitz","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Grundemann","given":"Laura","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Augustin","given":"Wolfgang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Scholl","given":"Stephan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Communications","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"8213-8228","publisher":"Royal Society of Chemistry","title":"Fouling in microstructured devices: a review","type":"article-journal","volume":"51"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1021/op100154d","ISSN":"10836160","abstract":"We investigate the mechanisms that govern plugging in microreactors during Pd-catalyzed amination reactions. Both bridging and constriction were shown to be important mechanisms that lead to clogging in our system and greatly limited the utility of microsystems for this class of reactions. On the basis of these observations, several approaches were engineered to overcome the challenge of plugging and to enable the continuous-flow synthesis of a biarylamine. Bridging could be eliminated with acoustic irradiation while constriction was managed via fluid velocity and the prediction of growth rates. ? 2010 American Chemical Society.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-3","issued":{"date-parts":[["2010"]]},"page":"1347-1357","title":"Overcoming the challenges of solid bridging and constriction during Pd-catalyzed C-N bond formation in microreactors","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-4","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1007/s41061-016-0070-y","ISBN":"2365-0869","ISSN":"03401022","abstract":"A compact snapshot of the current convergence of novel developments\\r\\nrelevant to chemical engineering is given. Process intensification concepts are\\r\\nanalysed through the lens of microfluidics and sonochemistry. Economical drivers\\r\\nand their influence on scientific activities are mentioned, including innovation\\r\\nopportunities towards deployment into society. We focus on the control of cavitation\\r\\nas a means to improve the energy efficiency of sonochemical reactors, as well\\r\\nas in the solids handling with ultrasound; both are considered the most difficult\\r\\nhurdles for its adoption in a practical and industrial sense. Particular examples for\\r\\nmicrofluidic clogging prevention, numbering-up and scaling-up strategies are given.\\r\\nTo conclude, an outlook of possible new directions of this active and promising\\r\\ncombination of technologies is hinted","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Topics in Current Chemistry","id":"ITEM-5","issue":"70","issued":{"date-parts":[["2016"]]},"publisher":"Springer International Publishing","title":"Synergy of Microfluidics and Ultrasound: Process Intensification Challenges and Opportunities","type":"article-journal","volume":"374"},"uris":[""]}],"mendeley":{"formattedCitation":"[13–15,24,26]","plainTextFormattedCitation":"[13–15,24,26]","previouslyFormattedCitation":"[13–15,24,26]"},"properties":{"noteIndex":0},"schema":""}[13–15,24,26]. In fact, in batch and large scale reactors, ultrasound has been widely used to intensify mixing, mass transfer and reaction rates in various chemical and biological processes ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.pbiomolbio.2006.07.026","abstract":"This paper is based on material presented at the start of a Health Protection Agency meeting on ultrasound and\\r\\ninfrasound. In answering the question ‘what is ultrasound?’, it shows that the simple description of a wave which\\r\\ntransports mechanical energy through the local vibration of particles at frequencies of 20 kHz or more, with no net\\r\\ntransport of the particles themselves, can in every respect be misleading or even incorrect. To explain the complexities\\r\\nresponsible for this, the description of ultrasound is first built up from the fundamental properties of these local particle\\r\\nvibrations. This progresses through an exposition of the characteristics of linear waves, in order to explain the propensity\\r\\nfor, and properties of, the nonlinear propagation which occurs in many practical ultrasonic fields. Given the Health\\r\\nProtection environment which framed the original presentation, explanation and examples are given of how these\\r\\ncomplexities affect issues of practical importance. These issues include the measurement and description of fields and\\r\\nexposures, and the ability of ultrasound to affect tissue (through microstreaming, streaming, cavitation, heating, etc.). It is\\r\\nnoted that there are two very distinct regimes, in terms of wave characteristics and potential for bioeffect. The first\\r\\nconcerns the use of ultrasound in liquids/solids, for measurement or material processing. For biomedical applications\\r\\n(where these two processes are termed diagnosis and therapy, respectively), the issue of hazard has been studied in depth,\\r\\nalthough this has not been done to such a degree for industrial uses of ultrasound in liquids/solids (sonar, non-destructive\\r\\ntesting, ultrasonic processing etc.). However, in the second regime, that of the use of ultrasound in air, although the waves\\r\\nin question tend to be of much lower intensities than those used in liquids/solids, there is a greater mismatch between the\\r\\nextent to which hazard has been studied, and the growth in commercial applications for airborne ultrasound.","author":[{"dropping-particle":"","family":"Leighton","given":"Timothy G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Progress in Biophysics and Molecular Biology","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"3-83","title":"What is ultrasound?","type":"article-journal","volume":"93"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cep.2007.09.014","ISSN":"02552701","abstract":"Cavitational reactors are a novel and promising form of multiphase reactors, based on the principle of release of large magnitude of energy due to the violent collapse of the cavities. An overview of this novel technology, in the specific area of process intensification of chemical processing applications, in terms of the basic mechanism and different areas of application has been presented initially. Recommendations for optimum operating parameters based on the theoretical analysis of cavitation phenomena as well as comparison with experimentally observed trends reported in the literature have been presented. A design of a pilot scale sonochemical reactor has been presented, which forms the basis for development of industrial scale reactors. Some experimental case studies using industrially important reactions have been presented, highlighting the degree of intensification achieved as compared to the conventional approaches. Guidelines for required further work for ensuring successful application of cavitational reactors at industrial scale operation have been presented. Overall it appears that considerable economic savings is possible by means of harnessing the spectacular effects of cavitation in chemical processing applications.","author":[{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing","id":"ITEM-2","issued":{"date-parts":[["2008"]]},"page":"515-527","title":"Cavitational reactors for process intensification of chemical processing applications: A critical review","type":"article-journal","volume":"47"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/b503848k","ISSN":"03060012","abstract":"Ultrasound, an efficient and virtually innocuous means of activation in synthetic chemistry, has been employed for decades with varied success. Not only can this high-energy input enhance mechanical effects in heterogeneous processes, but it is also known to induce new reactivities leading to the formation of unexpected chemical species. What makes sonochemistry unique is the remarkable phenomenon of cavitation, currently the subject of intense research which has already yielded thought-provoking results. This critical review is aimed at discussing the present status of cavitational chemistry and some of the underlying phenomena, and to highlight some recent applications and trends in organic sonochemistry, especially in combination with other sustainable technologies. ? The Royal Society of Chemistry 2006.","author":[{"dropping-particle":"","family":"Cravotto","given":"Giancarlo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cintas","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Society Reviews","id":"ITEM-3","issued":{"date-parts":[["2006"]]},"page":"180-196","title":"Power ultrasound in organic synthesis: moving cavitational chemistry from academia to innovative and large-scale applications","type":"article-journal","volume":"35"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.cej.2010.11.069","ISBN":"1385-8947","ISSN":"13858947","abstract":"The spectacular effects observed during acoustic cavitation phenomena have been successfully employed for a number of applications on laboratory scale of operation but a well defined design and scale up methodology is lacking. The present work aims at developing a unified approach for the selection of different operating and geometric parameters for large scale sonochemical reactors with a special emphasis on heterogeneous systems. In the case of heterogeneous systems, apart from optimum selection of operating and geometric parameters, it is also important to understand the mixing and hydrodynamic characteristics due to the presence of solid/gas phases in the liquid medium. Also the quantification of attenuation of the incident sound energy has been discussed, which can be important design consideration in heterogeneous systems. Recommendations have been made for optimum selection of frequency of irradiation and power dissipation rate/irradiation intensity as well as the liquid phase physicochemical properties for the given physicochemical transformation. The discussion also highlights' the recent advances in development of sonochemical reactors focusing on reactor geometry and location of transducers in batch and continuous scale of operation. ? 2010 Elsevier B.V.","author":[{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pandit","given":"Aniruddha B.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-4","issued":{"date-parts":[["2011"]]},"page":"1066-1082","publisher":"Elsevier B.V.","title":"Sonochemical reactors: Important design and scale up considerations with a special emphasis on heterogeneous systems","type":"article-journal","volume":"166"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1002/adma.200904093","ISSN":"09359648","abstract":"Recent advances in nanostructured materials have been led by the development of new synthetic methods that provide control over size, morphology, and nano/microstructure. The utilization of high intensity ultrasound offers a facile, versatile synthetic tool for nanostructured materials that are often unavailable by conventional methods. The primary physical phenomena associated with ultrasound that are relevant to materials synthesis are cavitation and nebulization. Acoustic cavitation (the formation, growth, and implosive collapse of bubbles in a liquid) creates extreme conditions inside the collapsing bubble and serves as the origin of most sonochemical phenomena in liquids or liquid-solid slurries. Nebulization (the creation of mist from ultrasound passing through a liquid and impinging on a liquid-gas interface) is the basis for ultrasonic spray pyrolysis (USP) with subsequent reactions occurring in the heated droplets of the mist. In both cases, we have examples of phase-separated attoliter microreactors: for sonochemistry, it is a hot gas inside bubbles isolated from one another in a liquid, while for USP it is hot droplets isolated from one another in a gas. Cavitation-induced sonochemistry provides a unique interaction between energy and matter, with hot spots inside the bubbles of approximately 5000 K, pressures of approximately 1000 bar, heating and cooling rates of >10(10) K s(-1); these extraordinary conditions permit access to a range of chemical reaction space normally not accessible, which allows for the synthesis of a wide variety of unusual nanostructured materials. Complementary to cavitational chemistry, the microdroplet reactors created by USP facilitate the formation of a wide range of nanocomposites. In this review, we summarize the fundamental principles of both synthetic methods and recent development in the applications of ultrasound in nanostructured materials synthesis.","author":[{"dropping-particle":"","family":"Ho Bang","given":"Jin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Suslick","given":"Kenneth S.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Advanced Materials","id":"ITEM-5","issued":{"date-parts":[["2010"]]},"note":"No Example of ultrasonic microreactor","page":"1039-1059","title":"Applications of Ultrasound to the Synthesis of Nanostructured Materials","type":"article-journal","volume":"22"},"uris":[""]}],"mendeley":{"formattedCitation":"[27–31]","plainTextFormattedCitation":"[27–31]","previouslyFormattedCitation":"[27–31]"},"properties":{"noteIndex":0},"schema":""}[27–31]. However, it is considered difficult to control and scale, due to non-uniformly generated acoustic fields and the complex flow patterns within conventional reactors ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2010.11.069","ISBN":"1385-8947","ISSN":"13858947","abstract":"The spectacular effects observed during acoustic cavitation phenomena have been successfully employed for a number of applications on laboratory scale of operation but a well defined design and scale up methodology is lacking. The present work aims at developing a unified approach for the selection of different operating and geometric parameters for large scale sonochemical reactors with a special emphasis on heterogeneous systems. In the case of heterogeneous systems, apart from optimum selection of operating and geometric parameters, it is also important to understand the mixing and hydrodynamic characteristics due to the presence of solid/gas phases in the liquid medium. Also the quantification of attenuation of the incident sound energy has been discussed, which can be important design consideration in heterogeneous systems. Recommendations have been made for optimum selection of frequency of irradiation and power dissipation rate/irradiation intensity as well as the liquid phase physicochemical properties for the given physicochemical transformation. The discussion also highlights' the recent advances in development of sonochemical reactors focusing on reactor geometry and location of transducers in batch and continuous scale of operation. ? 2010 Elsevier B.V.","author":[{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pandit","given":"Aniruddha B.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2011"]]},"page":"1066-1082","publisher":"Elsevier B.V.","title":"Sonochemical reactors: Important design and scale up considerations with a special emphasis on heterogeneous systems","type":"article-journal","volume":"166"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/1350-4177(95)00021-W","abstract":"Theoretical treatments of the dynamics of a single bubble in a pressure field have been undertaken for many decades. Although there is still scope for progress, there now exists a solid theoretical basis for the dynamics of a single bubble. This has enabled useful classifications to be established, including the distinction between stable cavitation (where a bubble pulsates for many cycles) and transient cavitation (where the bubble grows extensively over time-scales of the order of the acoustic cycle, and then undergoes an energetic collapse and subsequent rebound and then, potentially, either fragmentation, decaying oscillation or a repeat performance). Departures from sphericity, such as shape and surface oscillations and jetting, have also been characterized. However, in most practical systems involving high-energy cavitation (such as those involving sonochemical, biological and erosive effects), the bubbles do not behave as the isolated entities modelled by this single-bubble theory: the cavitational effect may be dominated by the characteristics of the entire bubble population, which may influence, and be influenced by, the sound field. The well established concepts that have resulted from the single-bubble theory must be reinterpreted in the light of the bubble population, an appreciation of population mechanisms being necessary to apply our understanding of single-bubble theory to many practical applications of 'power' ultrasound. Even at a most basic level these single-bubble theories describe the response of the bubble to the local sound field at the position of the bubble, and that pressure field will be influenced by the way sound is scattered by neighbouring bubbles. The influence of the bubble population will often go further, a non-uniform sound field creating an inhomogeneous bubble distribution. Such a distribution can scatter, channel and focus ultrasonic beams, can acoustically shield regions of the sample, and elsewhere localize the cavitational activity to discrete 'hot spots'. As a result, portions of the sample may undergo intense sonochemical activity, degassing, erosion, etc., whilst other areas remain relatively unaffected. Techniques exist to control such situations where they are desirable, and to eliminate this localization where a more uniform treatment of the sample is desired.","author":[{"dropping-particle":"","family":"Leighton","given":"T G","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issue":"2","issued":{"date-parts":[["1995"]]},"page":"S123-S136","title":"Bubble population phenomena in acoustic cavitation","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1205/cherd.05214","ISSN":"02638762","abstract":"This paper brings a review of the alternative sources and forms of energy that can be utilized in order to achieve drastic improvements in the efficiency of chemical and biochemical processes (process intensification). Literature data on achievable intensi- fication effects are provided. Also, some alternative ways of introducing energy in the chemical process equipment are presented. Although the process intensification potential of many of those alternative sources and forms of energy has already been proven in the labora- tories, their application on the industrial scale still presents a formidable challenge for the chemical engineering community. In the paper the most important design and scale-up pro- blems in those novel technologies are discussed and recommendations are given regarding the future research activities. To achieve radical progress in this area more research effort on the interface between the chemical engineering, chemistry, material science and applied physics is needed.","author":[{"dropping-particle":"","family":"Stankiewicz","given":"Andrzej","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-3","issue":"A7","issued":{"date-parts":[["2006"]]},"page":"511-521","title":"Alternative Sources and Forms of Energy for Intensification of Chemical and Biochemical Processes","type":"article-journal","volume":"84"},"uris":[""]}],"mendeley":{"formattedCitation":"[30,32,33]","plainTextFormattedCitation":"[30,32,33]","previouslyFormattedCitation":"[30,32,33]"},"properties":{"noteIndex":0},"schema":""}[30,32,33]. Small scale reactors on the other hand, offer a solution to these issues since the size range of ultrasonic effects are within the size range of that of the channels, see Figure 1. Therefore, the synergistic combination of them could utilizes one’s advantages to solve another’s problems ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2cc33920j","ISSN":"13597345","abstract":"Microfluidics enable the manipulation of chemical reactions using very small amounts of fluid, in channels with dimensions of tens to hundreds of micrometers; so-called microstructured devices, from which the iconic image of chips emerges. The immediate attraction of microfluidics lies in its greenness: use of small quantities of reagents and solvents, and hence less waste, a precise control of reaction conditions, integration of functionality for process intensification, safer and often faster protocols, reliable scale-up, and possibility of performing multiphase reactions. Among the limitations found in microfluidics the facile formation of precipitating products should be highlighted, and in this context, the search for efficient mass and energy transfers is a must. Such limitations have been partially overcome with the aid of ultrasound in conventional flow systems, and can now be successfully used in microreactors, which provide new capabilities. Novel applications and a better understanding of the physical and chemical aspects of sonochemistry can certainly be achieved by combining microfluidics and ultrasound. We will review this nascent area of research, paying attention to the latest developments and showing future directions, which benefit both from the existing microfluidic technology and sonochemistry itself. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cintas","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Communications","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"10935-10947","title":"Merging microfluidics and sonochemistry: Towards greener and more efficient micro-sono-reactors","type":"article-journal","volume":"48"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1007/s41061-016-0070-y","ISBN":"2365-0869","ISSN":"03401022","abstract":"A compact snapshot of the current convergence of novel developments\\r\\nrelevant to chemical engineering is given. Process intensification concepts are\\r\\nanalysed through the lens of microfluidics and sonochemistry. Economical drivers\\r\\nand their influence on scientific activities are mentioned, including innovation\\r\\nopportunities towards deployment into society. We focus on the control of cavitation\\r\\nas a means to improve the energy efficiency of sonochemical reactors, as well\\r\\nas in the solids handling with ultrasound; both are considered the most difficult\\r\\nhurdles for its adoption in a practical and industrial sense. Particular examples for\\r\\nmicrofluidic clogging prevention, numbering-up and scaling-up strategies are given.\\r\\nTo conclude, an outlook of possible new directions of this active and promising\\r\\ncombination of technologies is hinted","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Topics in Current Chemistry","id":"ITEM-3","issue":"70","issued":{"date-parts":[["2016"]]},"publisher":"Springer International Publishing","title":"Synergy of Microfluidics and Ultrasound: Process Intensification Challenges and Opportunities","type":"article-journal","volume":"374"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.11949/j.issn.0438-1157.20171366","abstract":"Both microreactor and sonochemistry technologies are important means to enhance chemical process, regardless of advantages and disadvantages in each technique. The concept of “sonochemical microreactor” is elucidated, which synergistic intensification can be achieved by integration of microreactor with sonochemistry technology. Ultrasound is used to intensify fluid mixing, enhance multi-phase mass transfer, prevent and dredge clogging in microchannel. In the meantime, microreactor is used to effectively control sound and bubble fields, and resolve amplification challenges of acoustic cavitation process. Further, acoustic cavitation behavior, regulation law of sound and bubble fields in sonochemical microreactor, and intensification mechanism of multi-phase mixing and mass transfer are presented indetail. Finally, future development direction in this area is envisioned Further study on spatiotemporal phenomena and theories at ultrasonic cavitation interface is the fundamental for realization and optimization of ultrasonic intensification.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Chemical Industry and Engineering","id":"ITEM-4","issue":"1","issued":{"date-parts":[["2018"]]},"page":"102-115","title":"Sonochemical microreactor - synergistic combination of ultrasound and microreactor","type":"article-journal","volume":"69"},"uris":[""]}],"mendeley":{"formattedCitation":"[26,34–36]","plainTextFormattedCitation":"[26,34–36]","previouslyFormattedCitation":"[26,34–36]"},"properties":{"noteIndex":0},"schema":""}[26,34–36].Ultrasound is generally classified into low and high frequency ultrasound due to the different physical mechanisms that can be induced. The boundary between low and high frequency ultrasound is not necessarily strict and the transition range is typically recognized within 200 kHz and 1 MHz, as shown in Figure 1. Low frequency ultrasound generates cavitation micro-bubbles, which can intensify mixing ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/b903687c","ISSN":"14730189","abstract":"We present ultra-fast homogeneous mixing inside a microfluidic channel via single-bubble-based acoustic streaming. The device operates by trapping an air bubble within a \"horse-shoe\" structure located between two laminar flows inside a microchannel. Acoustic waves excite the trapped air bubble at its resonance frequency, resulting in acoustic streaming, which disrupts the laminar flows and triggers the two fluids to mix. Due to this technique's simple design, excellent mixing performance, and fast mixing speed (a few milliseconds), our single-bubble-based acoustic micromixer may prove useful for many biochemical studies and applications. ? 2009 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mao","given":"Xiaole","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Shi","given":"Jinjie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Juluri","given":"Bala Krishna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Huang","given":"Tony Jun","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2009"]]},"page":"2738-2741","title":"A millisecond micromixer via single-bubble-based acoustic streaming","type":"article-journal","volume":"9"},"uris":[""]}],"mendeley":{"formattedCitation":"[24,37]","plainTextFormattedCitation":"[24,37]","previouslyFormattedCitation":"[24,37]"},"properties":{"noteIndex":0},"schema":""}[24,37] and interfacial mass transfer ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-1","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ces.2018.04.042","ISSN":"00092509","abstract":"The synergistic effects of gas agitation and ultrasound on mass transfer between immiscible liquids were investigated in an in-house made ultrasonic microreactor. With the introduction of inert gas (N2), a three-phase slug flow with slug bubbles either dispersed in continuous aqueous phase or encapsulated in oil plugs was observed. Under ultrasound irradiation, slug bubbles underwent surface wave oscillation and induced agitation in microchannel. In addition, microbubbles were generated by acoustic cavitation, oscillating intensely and resulting in the formation of O/W emulsion. Bubble oscillation (i.e., slug bubbles and microbubbles) as well as emulsification promoted liquid-liquid mass transfer significantly. Extraction of vanillin from aqueous solution to toluene was employed to demonstrate the mass transfer enhancement. Compared with silent operation, both mass transfer coefficient and extraction efficiency were largely improved by the combined use of gas agitation and ultrasound. With gas flow velocity being 0.005–0.083 m/s at fixed ultrasound power of 30 W, the overall mass transfer coefficients ranged from 0.047 s?1 to 0.429 s?1, which was 2.33–17.20 times larger than the corresponding liquid-liquid two-phase process without ultrasound irradiation.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Yanyan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-2","issued":{"date-parts":[["2018"]]},"page":"122-134","publisher":"Elsevier Ltd","title":"Intensification of liquid-liquid two-phase mass transfer by oscillating bubbles in ultrasonic microreactor","type":"article-journal","volume":"186"},"uris":[""]}],"mendeley":{"formattedCitation":"[38,39]","plainTextFormattedCitation":"[38,39]","previouslyFormattedCitation":"[38,39]"},"properties":{"noteIndex":0},"schema":""}[38,39], break up agglomerates ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.3390/cryst8070280","ISSN":"20734352","abstract":"When ultrasound is applied to a solution for crystallization, it can affect the properties of the crystalline products significantly. Ultrasonic irradiation decreases the induction time and metastable zone and increases the nucleation rate. Due to these effects, it generally yields smaller crystals with a narrower size distribution when compared with conventional crystallizations. Also, ultrasonic irradiation can cause fragmentation of existing crystals which is caused by crystal collisions or sonofragmentation. The effect of various experimental parameters and empirical products of sonocrystallization have been reported, but the mechanisms of sonocrystallization and sonofragmentation have not been confirmed clearly. In this review, we build upon previous studies and highlight the effects of ultrasound on the crystallization of organic molecules. In addition, recent work on sonofragmentation of molecular and ionic crystals is discussed.","author":[{"dropping-particle":"","family":"Na Kim","given":"Hyo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Suslick","given":"Kenneth S.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystals","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"280-300","title":"The Effects of Ultrasound on Crystals: Sonocrystallization and Sonofragmentation","type":"article-journal","volume":"8"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1021/acs.cgd.6b00088","ISSN":"15287505","abstract":"This paper investigates, for the first time, the breaking mechanism of particles exposed to implosions of stable and transient cavitation bubbles via Kapur function analysis. The effect of ultrasonic frequencies of 30-1140 kHz and powers of 4-200 W on particle breakage of paracetamol crystals was studied. The dominant cavitation bubble type was defined via sonoluminescence measurements. The breakage rate of seed crystals with a median size of 75 μm was found to be independent of the applied power when ultrasonically generated stable cavitation bubbles were generated. Furthermore, a particle size threshold of ca. 35 μm was observed. The particle size could not be reduced below this size regardless of the applied power or frequency. For transient bubbles, in contrast, higher powers lead to considerably smaller particles, with no threshold size within the investigated power range. The Kapur function analysis suggests that stable bubbles are more efficient than transient bubbles to break coarse particles with sizes above 40 μm. Finally, cumulative breakage functions were calculated, and it was observed that transient bubbles generate more abrasion than stable bubbles.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Appermont","given":"Tessa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gielen","given":"Bjorn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"6167-6177","title":"Sonofragmentation: Effect of Ultrasound Frequency and Power on Particle Breakage","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[40,41]","plainTextFormattedCitation":"[40,41]","previouslyFormattedCitation":"[40,41]"},"properties":{"noteIndex":0},"schema":""}[40,41] and detach particles deposited on microchannel surfaces to prevent clogging ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.partic.2018.08.009","ISSN":"22104291","abstract":"? 2019 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences The integration of microreactor and ultrasound represents an emerging area for process intensification and has attracted considerable attention in recent years. One of the most important meso-scientific issues in ultrasound techniques is acoustic cavitation, which plays a vital role in the macroscopic performance of an ultrasonic microreactor. In this review, we first briefly summarize the latest research on acoustic cavitation phenomena in microreactors. The effects of channel configuration, solvent properties, and ultrasound parameters are systematically reviewed. In addition, the role of acoustic cavitation in various chemical processes (e.g., mixing, absorption, emulsification, and particle synthesis) is presented from a mesoscale perspective, which in turn provides guidance for ultrasound applications. A thorough understanding of the ultrasound intensification mechanism will contribute to the future development of this promising technology.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuinan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Particuology","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"title":"Role of ultrasonic oscillation in chemical processes in microreactors: A mesoscale issue","type":"article-journal"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c1lc20337a","ISSN":"14730189","abstract":"We present a general inexpensive method for realizing a Teflon stack microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The microreactors are demonstrated with palladium-catalyzed C-N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. Investigations of the ultrasonic waveform applied by the piezoelectric actuator reveal an optimal value of 50 kHz at a load power of 30 W. Operating the system at these conditions, the newly developed Teflon microreactor handles the insoluble solids formed and no clogging is observed. The investigated reactions reach full conversion in very short reaction times and high isolated yields are obtained (>95% yield).","author":[{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heider","given":"Patrick L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issue":"15","issued":{"date-parts":[["2011"]]},"page":"2488-2492","title":"A Teflon microreactor with integrated piezoelectric actuator to handle solid forming reactions","type":"article-journal","volume":"11"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.cej.2012.11.014","ISSN":"13858947","abstract":"This paper describes the continuous-flow precipitation of hydroxyapatite Ca5(PO4)3OH (HAp) in two ultrasonic microreactors using diluted aqueous solutions of calcium and phosphate at 37°C. Precipitation of HAp was first carried out in a tubular microreactor immersed in an ultrasonic bath, where single-phase (laminar) flow and segmented gas-liquid flow were both evaluated. The single-phase flow study was then conducted in a novel microfluidic device developed at MIT. It consists of a Teflon stack microreactor with an integrated piezoelectric element (Teflon microreactor), thereby allowing the direct transmission of ultrasound to the reactor. Both microsystems produce single-phased calcium-deficient carbonated HAp under near-physiological conditions of temperature and pH. In addition, particle aggregation and primary particle size were significantly reduced in the segmented-flow tubular microreactor and in the Teflon microreactor. The as-prepared particles mostly consisted of rod-like shape nanoparticles with dimensions below 100nm in length and around 20nm in width. Further, the microreactors used yielded HAp particles with improved characteristics, namely higher crystallinity and less carbonate contamination, when compared to the HAp particles produced in a stirred tank batch reactor. ? 2012 Elsevier B.V.","author":[{"dropping-particle":"","family":"Castro","given":"Filipa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ferreira","given":"António","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rocha","given":"Fernando","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Vicente","given":"António","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"José António","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-3","issued":{"date-parts":[["2013"]]},"page":"979-987","publisher":"Elsevier B.V.","title":"Continuous-flow precipitation of hydroxyapatite in ultrasonic microsystems","type":"article-journal","volume":"215-216"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]}],"mendeley":{"formattedCitation":"[42–45]","plainTextFormattedCitation":"[42–45]","previouslyFormattedCitation":"[42–45]"},"properties":{"noteIndex":0},"schema":""}[42–45]. Secondly, the induced cavitation bubble’s resonance size matches that of the channel, making it an ideal platform to investigate and harness cavitation effects ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2cc33920j","ISSN":"13597345","abstract":"Microfluidics enable the manipulation of chemical reactions using very small amounts of fluid, in channels with dimensions of tens to hundreds of micrometers; so-called microstructured devices, from which the iconic image of chips emerges. The immediate attraction of microfluidics lies in its greenness: use of small quantities of reagents and solvents, and hence less waste, a precise control of reaction conditions, integration of functionality for process intensification, safer and often faster protocols, reliable scale-up, and possibility of performing multiphase reactions. Among the limitations found in microfluidics the facile formation of precipitating products should be highlighted, and in this context, the search for efficient mass and energy transfers is a must. Such limitations have been partially overcome with the aid of ultrasound in conventional flow systems, and can now be successfully used in microreactors, which provide new capabilities. Novel applications and a better understanding of the physical and chemical aspects of sonochemistry can certainly be achieved by combining microfluidics and ultrasound. We will review this nascent area of research, paying attention to the latest developments and showing future directions, which benefit both from the existing microfluidic technology and sonochemistry itself. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cintas","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Communications","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"10935-10947","title":"Merging microfluidics and sonochemistry: Towards greener and more efficient micro-sono-reactors","type":"article-journal","volume":"48"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1007/s41061-016-0070-y","ISBN":"2365-0869","ISSN":"03401022","abstract":"A compact snapshot of the current convergence of novel developments\\r\\nrelevant to chemical engineering is given. Process intensification concepts are\\r\\nanalysed through the lens of microfluidics and sonochemistry. Economical drivers\\r\\nand their influence on scientific activities are mentioned, including innovation\\r\\nopportunities towards deployment into society. We focus on the control of cavitation\\r\\nas a means to improve the energy efficiency of sonochemical reactors, as well\\r\\nas in the solids handling with ultrasound; both are considered the most difficult\\r\\nhurdles for its adoption in a practical and industrial sense. Particular examples for\\r\\nmicrofluidic clogging prevention, numbering-up and scaling-up strategies are given.\\r\\nTo conclude, an outlook of possible new directions of this active and promising\\r\\ncombination of technologies is hinted","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Topics in Current Chemistry","id":"ITEM-3","issue":"70","issued":{"date-parts":[["2016"]]},"publisher":"Springer International Publishing","title":"Synergy of Microfluidics and Ultrasound: Process Intensification Challenges and Opportunities","type":"article-journal","volume":"374"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.11949/j.issn.0438-1157.20171366","abstract":"Both microreactor and sonochemistry technologies are important means to enhance chemical process, regardless of advantages and disadvantages in each technique. The concept of “sonochemical microreactor” is elucidated, which synergistic intensification can be achieved by integration of microreactor with sonochemistry technology. Ultrasound is used to intensify fluid mixing, enhance multi-phase mass transfer, prevent and dredge clogging in microchannel. In the meantime, microreactor is used to effectively control sound and bubble fields, and resolve amplification challenges of acoustic cavitation process. Further, acoustic cavitation behavior, regulation law of sound and bubble fields in sonochemical microreactor, and intensification mechanism of multi-phase mixing and mass transfer are presented indetail. Finally, future development direction in this area is envisioned Further study on spatiotemporal phenomena and theories at ultrasonic cavitation interface is the fundamental for realization and optimization of ultrasonic intensification.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Chemical Industry and Engineering","id":"ITEM-4","issue":"1","issued":{"date-parts":[["2018"]]},"page":"102-115","title":"Sonochemical microreactor - synergistic combination of ultrasound and microreactor","type":"article-journal","volume":"69"},"uris":[""]}],"mendeley":{"formattedCitation":"[26,34–36]","plainTextFormattedCitation":"[26,34–36]","previouslyFormattedCitation":"[26,34–36]"},"properties":{"noteIndex":0},"schema":""}[26,34–36]. High frequency ultrasound, on the other hand, is operated at power levels below the cavitation threshold, therefore cavitation effects are normally not observed. However, the wavelength in most fluids matches the channel size, making it possible to form a standing wave within the channel and utilize the associated effects, such as acoustic radiation force and streaming, see Figure 1a ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2014.02.016","ISSN":"18732828","PMID":"24629579","abstract":"Ultrasonic standing waves (USW) separation is an established technology for micro scale applications due to the excellent control to manipulate particles acoustically achieved when combining high frequency ultrasound with laminar flow in microchannels, allowing the development of numerous applications. Larger scale systems (pilot to industrial) are emerging; however, scaling up such processes are technologically very challenging. This paper reviews the physical principles that govern acoustic particle/droplet separation and the mathematical modeling techniques developed to understand, predict, and design acoustic separation processes. A further focus in this review is on acoustic streaming, which represents one of the major challenges in scaling up USW separation processes. The manuscript concludes by providing a brief overview of the state of the art of the technology applied in large scale systems with potential applications in the dairy and oil industries. ? 2014 Published by Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Trujillo","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Juliano","given":"Pablo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Barbosa-Cánovas","given":"Gustavo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Knoerzer","given":"Kai","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"2151-2164","publisher":"Elsevier B.V.","title":"Separation of suspensions and emulsions via ultrasonic standing waves - A review","type":"article-journal","volume":"21"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2lc21256k","ISSN":"14730189","abstract":"This acoustofluidics tutorial focuses on continuous flow-based half wavelength resonator systems operated in the transversal mode, where the direction of the primary acoustic force acts in plane with the microchip. The transversal actuation mode facilitates integration with up- and downstream microchannel networks as well as visual control of the acoustic focusing experiment. Applications of particle enrichment in an acoustic half wavelength resonator are discussed as well as clarification of the carrier fluid from undesired particles. Binary separation of particle/vesicle/cell mixtures into two subpopulations is outlined based on the different polarities of the acoustic contrast factor. Furthermore, continuous flow separation of different particle/cell types is described where both Free Flow Acoustophoresis (FFA) and binary acoustophoresis are utilized. By capitalizing on the laminar flow regime, acoustophoresis has proven especially successful in performing bead/cell translations between different buffer systems. Likewise, the ability to controllably translate particulate matter across streamlines has opened a route to valving of cells/particles without any moving parts, where event triggered cell sorting is becoming an increasing area of activity. Recent developments now also enable measurements of fundamental cell properties such as density and compressibility by means of acoustophoresis. General aspects on working with live cells in acoustophoresis systems are discussed as well as available means to quantify the outcome of cell and particle separation experiments performed by acoustophoresis. ? The Royal Society of Chemistry 2012.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Magnusson","given":"Cecilia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"1210-1223","title":"Acoustofluidics 8: Applications of acoustophoresis in continuous flow microsystems","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.bios.2006.08.023","ISSN":"09565663","abstract":"Direct radiation force (DRF) and acoustic streaming provide the main influences on the behaviour of particles in aqueous suspension in an ultrasound standing wave (USW). The direct radiation force, which drives suspended particles towards and concentrates them in acoustic pressure node planes, has been applied to rapidly transfer cells in small scale analytical separators. The DRF also significantly increased the sensitivity of latex agglutination test (LAT) by concentrating the particles of an analytical sample in the pressure node positions and hence greatly increasing the antibody-antigen encounter rate. Capture of biotinylated particles and spores on a coated acoustic reflector in a quarter wavelength USW resonator was DRF-enhanced by 70- and 100-fold, respectively compared to the situation in the absence of ultrasound. Acoustic streaming has been successfully employed for mixing small analytical samples. Cavitation micro-streaming substantially enhanced, through mixing, DNA hybridization and the capture efficiency of Escherichia coli K12 on the surface of immunomagnetic beads. Acoustic streaming induced in longitudinal standing wave and flexural plate wave immuno-sensors increased the detection of antigens by a factor of five and three times, respectively. Combined DRF and acoustic streaming effects enhanced the rate of the reaction between suspended mixture of cells and retroviruses. The examples of a biochip and an ultrasonic immuno-sensor implementing the DRF and acoustic streaming effects are also described in the review. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Kuznetsova","given":"Larisa A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coakley","given":"W. Terence","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biosensors and Bioelectronics","id":"ITEM-3","issued":{"date-parts":[["2007"]]},"page":"1567-1577","title":"Applications of ultrasound streaming and radiation force in biosensors","type":"article-journal","volume":"22"},"uris":[""]}],"mendeley":{"formattedCitation":"[46–48]","plainTextFormattedCitation":"[46–48]","previouslyFormattedCitation":"[46–48]"},"properties":{"noteIndex":0},"schema":""}[46–48]. The radiation force is able to displace particles to pressure nodes, while the resulting acoustic streaming is able to enhance mixing ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c2lc21256k","ISSN":"14730189","abstract":"This acoustofluidics tutorial focuses on continuous flow-based half wavelength resonator systems operated in the transversal mode, where the direction of the primary acoustic force acts in plane with the microchip. The transversal actuation mode facilitates integration with up- and downstream microchannel networks as well as visual control of the acoustic focusing experiment. Applications of particle enrichment in an acoustic half wavelength resonator are discussed as well as clarification of the carrier fluid from undesired particles. Binary separation of particle/vesicle/cell mixtures into two subpopulations is outlined based on the different polarities of the acoustic contrast factor. Furthermore, continuous flow separation of different particle/cell types is described where both Free Flow Acoustophoresis (FFA) and binary acoustophoresis are utilized. By capitalizing on the laminar flow regime, acoustophoresis has proven especially successful in performing bead/cell translations between different buffer systems. Likewise, the ability to controllably translate particulate matter across streamlines has opened a route to valving of cells/particles without any moving parts, where event triggered cell sorting is becoming an increasing area of activity. Recent developments now also enable measurements of fundamental cell properties such as density and compressibility by means of acoustophoresis. General aspects on working with live cells in acoustophoresis systems are discussed as well as available means to quantify the outcome of cell and particle separation experiments performed by acoustophoresis. ? The Royal Society of Chemistry 2012.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Magnusson","given":"Cecilia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"1210-1223","title":"Acoustofluidics 8: Applications of acoustophoresis in continuous flow microsystems","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.bios.2006.08.023","ISSN":"09565663","abstract":"Direct radiation force (DRF) and acoustic streaming provide the main influences on the behaviour of particles in aqueous suspension in an ultrasound standing wave (USW). The direct radiation force, which drives suspended particles towards and concentrates them in acoustic pressure node planes, has been applied to rapidly transfer cells in small scale analytical separators. The DRF also significantly increased the sensitivity of latex agglutination test (LAT) by concentrating the particles of an analytical sample in the pressure node positions and hence greatly increasing the antibody-antigen encounter rate. Capture of biotinylated particles and spores on a coated acoustic reflector in a quarter wavelength USW resonator was DRF-enhanced by 70- and 100-fold, respectively compared to the situation in the absence of ultrasound. Acoustic streaming has been successfully employed for mixing small analytical samples. Cavitation micro-streaming substantially enhanced, through mixing, DNA hybridization and the capture efficiency of Escherichia coli K12 on the surface of immunomagnetic beads. Acoustic streaming induced in longitudinal standing wave and flexural plate wave immuno-sensors increased the detection of antigens by a factor of five and three times, respectively. Combined DRF and acoustic streaming effects enhanced the rate of the reaction between suspended mixture of cells and retroviruses. The examples of a biochip and an ultrasonic immuno-sensor implementing the DRF and acoustic streaming effects are also described in the review. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Kuznetsova","given":"Larisa A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coakley","given":"W. Terence","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biosensors and Bioelectronics","id":"ITEM-2","issued":{"date-parts":[["2007"]]},"page":"1567-1577","title":"Applications of ultrasound streaming and radiation force in biosensors","type":"article-journal","volume":"22"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1039/c2lc40203c","ISSN":"14730189","abstract":"In part 14 of the tutorial series \"Acoustofluidics - exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation\", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Wiklund","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Green","given":"Roy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohlin","given":"Mathias","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-4","issue":"14","issued":{"date-parts":[["2012"]]},"page":"2438-2451","title":"Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[47–50]","plainTextFormattedCitation":"[47–50]","previouslyFormattedCitation":"[47–50]"},"properties":{"noteIndex":0},"schema":""}[47–50]. These principles have already been successfully implemented in microreactors for acoustofluidic applications, such as cell/particle manipulation (separation, concentration and sorting) and fluid mixing for biological and chemical processes ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2014.02.016","ISSN":"18732828","PMID":"24629579","abstract":"Ultrasonic standing waves (USW) separation is an established technology for micro scale applications due to the excellent control to manipulate particles acoustically achieved when combining high frequency ultrasound with laminar flow in microchannels, allowing the development of numerous applications. Larger scale systems (pilot to industrial) are emerging; however, scaling up such processes are technologically very challenging. This paper reviews the physical principles that govern acoustic particle/droplet separation and the mathematical modeling techniques developed to understand, predict, and design acoustic separation processes. A further focus in this review is on acoustic streaming, which represents one of the major challenges in scaling up USW separation processes. The manuscript concludes by providing a brief overview of the state of the art of the technology applied in large scale systems with potential applications in the dairy and oil industries. ? 2014 Published by Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Trujillo","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Juliano","given":"Pablo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Barbosa-Cánovas","given":"Gustavo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Knoerzer","given":"Kai","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"2151-2164","publisher":"Elsevier B.V.","title":"Separation of suspensions and emulsions via ultrasonic standing waves - A review","type":"article-journal","volume":"21"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c4lc01246a","ISSN":"14730189","PMID":"25598308","abstract":"Accurate and high throughput cell sorting is a critical enabling technology in molecular and cellular biology, biotechnology, and medicine. While conventional methods can provide high efficiency sorting in short timescales, advances in microfluidics have enabled the realization of miniaturized devices offering similar capabilities that exploit a variety of physical principles. We classify these technologies as either active or passive. Active systems generally use external fields (e.g., acoustic, electric, magnetic, and optical) to impose forces to displace cells for sorting, whereas passive systems use inertial forces, filters, and adhesion mechanisms to purify cell populations. Cell sorting on microchips provides numerous advantages over conventional methods by reducing the size of necessary equipment, eliminating potentially biohazardous aerosols, and simplifying the complex protocols commonly associated with cell sorting. Additionally, microchip devices are well suited for parallelization, enabling complete lab-on-a-chip devices for cellular isolation, analysis, and experimental processing. In this review, we examine the breadth of microfluidic cell sorting technologies, while focusing on those that offer the greatest potential for translation into clinical and industrial practice and that offer multiple, useful functions. We organize these sorting technologies by the type of cell preparation required (i.e., fluorescent label-based sorting, bead-based sorting, and label-free sorting) as well as by the physical principles underlying each sorting mechanism.","author":[{"dropping-particle":"","family":"Wyatt Shields Iv","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Reyes","given":"Catherine D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"López","given":"Gabriel P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issue":"5","issued":{"date-parts":[["2015"]]},"page":"1230-1249","publisher":"Royal Society of Chemistry","title":"Microfluidic cell sorting: A review of the advances in the separation of cells from debulking to rare cell isolation","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/c2lc40999b","ISSN":"14730189","abstract":"This part of the Acoustofluidics tutorial series reviews applications in acoustic trapping of micron-sized particles and cells in microfluidic systems. Acoustic trapping enables non-invasive and non-contact immobilisation of cells and particles in microfluidic systems. Acoustic trapping has been used for reducing the time needed to create 3D cell clusters, enhance particle-based bioassays and facilitated interaction studies of both cells and particles. An area that is increasingly interesting is the use of acoustic trapping for enriching low concentration samples and the washing or fractioning of cell populations prior to sensitive detection methods (MALDI-MS, PCR etc.) The main focus of the review is systems where particles can be retained against a flow while applications in which particles are positioned in a stationary fluid will be addressed in part 21 of the Acoustofluidics tutorial series (M. Wiklund, S. Radel and J. J. Hawkes, Lab Chip, 2012, 12, DOI: 10.1039/c2lc41073g). ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Evander","given":"Mikael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2012"]]},"page":"4667-4676","title":"Acoustofluidics 20: Applications in acoustic trapping","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.3390/cryst9030120","ISSN":"20734352","abstract":"Manipulation of high-density materials, such as crystals and liquid condensates, is of great importance for many applications, including serial crystallography, structural and molecular biology, chemistry, and medicine. In this work, we describe an acoustic technique to focus and harvest flowing crystals and liquid condensates. Moreover, we show, based on numerical simulations, that the acoustic waves can be used for size-based particle (crystals, droplets, etc.) separation. This is an essential technological step in biological research, medical applications, and industrial processes. The presented technology offers high precision, biocompatibility, ease of use and additionally, is non-invasive and inexpensive. With the recent advent of X-ray Free Electron Laser (XFEL) technology and the associated enormous importance of a thin jet of crystals, this technology might pave the way to a novel type of XFEL injector.","author":[{"dropping-particle":"","family":"Gelin","given":"Pierre","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lindt","given":"Joris","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bratek-Skicki","given":"Anna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stroobants","given":"Sander","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Krzek","given":"Marzena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ziemecka","given":"Iwona","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tompa","given":"Peter","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Malsche","given":"Wim","non-dropping-particle":"De","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Maes","given":"Dominique","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystals","id":"ITEM-4","issue":"120","issued":{"date-parts":[["2019"]]},"note":"focus crystals for online analysis.","page":"1-9","title":"Focusing of Microcrystals and Liquid Condensates in Acoustofluidics","type":"article-journal","volume":"9"},"uris":[""]}],"mendeley":{"formattedCitation":"[46,51–53]","plainTextFormattedCitation":"[46,51–53]","previouslyFormattedCitation":"[46,51–53]"},"properties":{"noteIndex":0},"schema":""}[46,51–53]. More recently studies show that particle manipulation using high frequency ultrasound, can also decrease solid attachment on channel walls and in turn prevent clogging ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.3390/s17010106","ISSN":"14248220","abstract":"??? 2017 by the authors; licensee MDPI, Basel, Switzerland. Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 ???m microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO 3 wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging.","author":[{"dropping-particle":"","family":"Sriphutkiat","given":"Yannapol","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhou","given":"Yufeng","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Sensors","id":"ITEM-2","issue":"106","issued":{"date-parts":[["2017"]]},"note":"Already Mentioned","page":"1-18","title":"Particle Accumulation in a Microchannel and Its Reduction by a Standing Surface Acoustic Wave (SSAW)","type":"article-journal","volume":"17"},"uris":[""]}],"mendeley":{"formattedCitation":"[49,54]","plainTextFormattedCitation":"[49,54]","previouslyFormattedCitation":"[49,54]"},"properties":{"noteIndex":0},"schema":""}[49,54].Despite the many advantages and large number of studies on the combination of ultrasound with flow reactors, there are still a few challenges remaining, especially when it comes to scalability. These challenges include the efficient transfer of ultrasound energy from transducer to reactor as well as methods to utilize and promote ultrasonic effects, all in a bid to improve the energy efficiency of reactors. This review aims at addressing these challenges and summarizes the state of the art of ultrasonic small scale flow reactors, as well as providing a guideline to the design, characterization, application and scaling of these systems.Figure 1. Representation of the key concepts behind ultrasonic small scale flow reactors. Firstly, (a) the different phenomena associated with high and low frequency ultrasound, (b) the ultrasonic frequency (f) and the corresponding wavelength (λ) in water, (c) the cavitation bubble resonance size for low frequency ultrasound (20 kHz– to 1 MHz) and (d) how the associated ultrasonic phenomena match the typical size range of micro and milli-reactor channels.2. Physical mechanisms of ultrasoundThe different physical mechanisms behind ultrasound are the reason for its versatility. Understanding these mechanisms lead to reactor designs that utilize the effects more efficiently and provides methods to improve reactor performance.2.1. Cavitation phenomena in microchannelsAlmost all applications of low frequency ultrasound are based on cavitation effects. When ultrasound is applied in a liquid, cavitation microbubbles are generated from gas nuclei dissolved in the liquid or trapped at the reactor wall ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2012.04.013","ISSN":"18732828","abstract":"The physics and chemistry of nonlinearly oscillating acoustic cavitation bubbles are strongly influenced by the dissolved gas in the surrounding liquid. Changing the gas alters among others the luminescence spectrum, and the radical production of the collapsing bubbles. An overview of experiments with various gas types and concentration described in literature is given and is compared to mechanisms that lead to the observed changes in luminescence spectra and radical production. The dissolved gas type changes the bubble adiabatic ratio, thermal conductivity, and the liquid surface tension, and consequently the hot spot temperature. The gas can also participate in chemical reactions, which can enhance radical production or luminescence of a cavitation bubble. With this knowledge, the gas content in cavitation can be tailored to obtain the desired output. ? 2012 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Rooze","given":"Joost","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Rebrov","given":"Evgeny","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schouten","given":"Jaap C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Keurentjes","given":"Jos T.F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2013"]]},"page":"1-11","title":"Dissolved gas and ultrasonic cavitation - A review","type":"article-journal","volume":"20"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2012.07.024","ISSN":"18732828","abstract":"We describe the ejection of bubbles from air-filled pits micromachined on a silicon surface when exposed to ultrasound at a frequency of approximately 200 kHz. As the pressure amplitude is increased the bubbles ejected from the micropits tend to be larger and they interact in complex ways. With more than one pit, there is a threshold pressure beyond which the bubbles follow a trajectory parallel to the substrate surface and converge at the center point of the pit array. We have determined the size distribution of bubbles ejected from one, two and three pits, for three different pressure amplitudes and correlated them with sonochemical OH? radical production. Experimental evidence of shock wave emission from the bubble clusters, deformed bubble shapes and jetting events that might lead to surface erosion are presented. We describe numerical simulations of sonochemical conversion using the empirical bubble size distributions, and compare the calculated values with experimental results. ? 2012 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stricker","given":"Laura","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zijlstra","given":"Aaldert G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lohse","given":"Detlef","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Prosperetti","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2013"]]},"page":"510-524","publisher":"Elsevier B.V.","title":"Ultrasound artificially nucleated bubbles and their sonochemical radical production","type":"article-journal","volume":"20"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2018.04.015","ISSN":"18732828","abstract":"The interest in application of ultrasonic cavitation for cleaning and surface treatment processes has increased greatly in the last decades. However, not much is known about the behavior of cavitation bubbles inside the microstructural features of the solid substrates. Here we report on an experimental study on dynamics of acoustically driven (38.5 kHz) cavitation bubbles inside the blind and through holes of PMMA plates by using high-speed imaging. Various diameters of blind (150, 200, 250 and 1000 ?m) and through holes (200 and 1000 ?m) were investigated. Gas bubbles are usually trapped in the holes during substrate immersion in the liquid thus preventing their complete wetting. We demonstrate that trapped gas can be successfully removed from the holes under ultrasound agitation. Besides the primary Bjerknes force and acoustic streaming, the shape oscillations of the trapped gas bubble seem to be a driving force for bubble removal out of the holes. We further discuss the bubble dynamics inside microholes for water and Cu2+ salt solution. It is found that the hole diameter and partly the type of liquid media influences the number, size and dynamics of the cavitation bubbles. The experiments also showed that a large amount of the liquid volume inside the holes can be displaced within one acoustic cycle by the expansion of the cavitation bubbles. This confirmed that ultrasound is a very effective tool to intensify liquid exchange processes, and it might significantly improve micro mixing in small structures. The investigation of the effect of ultrasound power on the bubble density distribution revealed the possibility to control the cavitation bubble distribution inside the microholes. At a high ultrasound power (31.5 W) we observed the highest bubble density at the hole entrances, while reducing the ultrasound power by a factor of ten shifted the bubble locations to the inner end of the blind holes or to the middle of the through holes.","author":[{"dropping-particle":"","family":"Kauer","given":"Markus","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Belova-Magri","given":"Valentina","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cairós","given":"Carlos","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Linka","given":"Gerd","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mettin","given":"Robert","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2018"]]},"page":"39-50","publisher":"Elsevier","title":"High-speed imaging of ultrasound driven cavitation bubbles in blind and through holes","type":"article-journal","volume":"48"},"uris":[""]}],"mendeley":{"formattedCitation":"[55–57]","plainTextFormattedCitation":"[55–57]","previouslyFormattedCitation":"[55–57]"},"properties":{"noteIndex":0},"schema":""}[55–57]. The formation, growth, oscillation, and collapse of these bubbles under the influence of the sound field is termed as acoustic cavitation ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.pbiomolbio.2006.07.026","abstract":"This paper is based on material presented at the start of a Health Protection Agency meeting on ultrasound and\\r\\ninfrasound. In answering the question ‘what is ultrasound?’, it shows that the simple description of a wave which\\r\\ntransports mechanical energy through the local vibration of particles at frequencies of 20 kHz or more, with no net\\r\\ntransport of the particles themselves, can in every respect be misleading or even incorrect. To explain the complexities\\r\\nresponsible for this, the description of ultrasound is first built up from the fundamental properties of these local particle\\r\\nvibrations. This progresses through an exposition of the characteristics of linear waves, in order to explain the propensity\\r\\nfor, and properties of, the nonlinear propagation which occurs in many practical ultrasonic fields. Given the Health\\r\\nProtection environment which framed the original presentation, explanation and examples are given of how these\\r\\ncomplexities affect issues of practical importance. These issues include the measurement and description of fields and\\r\\nexposures, and the ability of ultrasound to affect tissue (through microstreaming, streaming, cavitation, heating, etc.). It is\\r\\nnoted that there are two very distinct regimes, in terms of wave characteristics and potential for bioeffect. The first\\r\\nconcerns the use of ultrasound in liquids/solids, for measurement or material processing. For biomedical applications\\r\\n(where these two processes are termed diagnosis and therapy, respectively), the issue of hazard has been studied in depth,\\r\\nalthough this has not been done to such a degree for industrial uses of ultrasound in liquids/solids (sonar, non-destructive\\r\\ntesting, ultrasonic processing etc.). However, in the second regime, that of the use of ultrasound in air, although the waves\\r\\nin question tend to be of much lower intensities than those used in liquids/solids, there is a greater mismatch between the\\r\\nextent to which hazard has been studied, and the growth in commercial applications for airborne ultrasound.","author":[{"dropping-particle":"","family":"Leighton","given":"Timothy G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Progress in Biophysics and Molecular Biology","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"3-83","title":"What is ultrasound?","type":"article-journal","volume":"93"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"","author":[{"dropping-particle":"","family":"Grieser","given":"Franz","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Choi","given":"Pak Kon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Enomoto","given":"Naoya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Harada","given":"Hisashi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Okitsu","given":"Kenji","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yasui","given":"Kyuichi","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-2","issued":{"date-parts":[["2015"]]},"publisher":"Elsevier","title":"Sonochemistry and the Acoustic Bubble","type":"book"},"uris":[""]},{"id":"ITEM-3","itemData":{"author":[{"dropping-particle":"","family":"Mason","given":"Timothy J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lorimer","given":"John P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"editor":[{"dropping-particle":"","family":"Anderson","given":"Bill","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-3","issued":{"date-parts":[["2002"]]},"publisher":"Wiley","title":"Applied Sonochemistry: the uses of power ultrasound in chemistry and processing","type":"book"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultsonch.2010.11.016","ISSN":"13504177","abstract":"Acoustic cavitation, in simple terms, is the growth and collapse of preexisting microbubbles under the influence of an ultrasonic field in liquids. The cavitation bubbles can be characterized by the dynamics of oscillations and the maximum temperatures and pressures reached when they collapse. These aspects can be studied both experimentally and theoretically for a single bubble system. However, in a multibubble system, the formation of bubble streamers and clusters makes it difficult to characterize the cumulative properties of these bubbles. In this overview, some recently developed experimental procedures for the characterization of acoustic cavitation bubbles have been discussed. ? 2010 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Ashokkumar","given":"Muthupandian","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2011"]]},"page":"864-872","title":"The characterization of acoustic cavitation bubbles - An overview","type":"paper-conference","volume":"18"},"uris":[""]},{"id":"ITEM-5","itemData":{"ISSN":"08146039","abstract":"The principal method behind applications of power ultrasound is that of acoustic cavitation. This paper aims to provide an overview of bubble behaviour during acoustic cavitation, including phenomena such as transient and stable cavitation, rectified diffusion, coalescence and sonoluminescence. Application of these effects to processes such as nanomaterial synthesis, emulsion formation and waste water treatment is then described.","author":[{"dropping-particle":"","family":"Leong","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ashokkumar","given":"Muthupandian","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sandra","given":"Kentish","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Acoustics Australia","id":"ITEM-5","issue":"2","issued":{"date-parts":[["2011"]]},"page":"54-63","title":"The fundamentals of power ultrasound - A review","type":"article-journal","volume":"39"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1121/1.3650537","abstract":"This paper reports on noninertial cavitation that occurs beyond the zone close to the horn tip to which the inertial cavitation is confined. The noninertial cavitation is characterized by collating the data from a range of measurements of bubbles trapped on a solid surface in this noninertial zone. Specifically, the electrochemical measurement of mass transfer to an electrode is compared with high-speed video of the bubble oscillation. This gas bubble is shown to be a “noninertial” event by electrochemical surface erosion measurements and “ring-down” experiments showing the activity and motion of the bubble as the sound excitation was terminated. These measurements enable char- acterization of the complex environment produced below an operating ultrasonic horn outside of the region where inertial collapse can be detected. The extent to which solid boundaries in the liq- uid cause the frequencies and shapes of oscillatory modes on the bubble wall to differ from their free field values is discussed.","author":[{"dropping-particle":"","family":"Birkin","given":"Peter R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Offin","given":"Douglas G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Vian","given":"Christopher J. B.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Leighton","given":"Timothy G","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"J. Acoust. Soc. Am.","id":"ITEM-6","issue":"5","issued":{"date-parts":[["2011"]]},"page":"3297-3308","title":"Investigation of noninertial cavitation produced by an ultrasonic horn","type":"article-journal","volume":"130"},"uris":[""]}],"mendeley":{"formattedCitation":"[27,58–62]","plainTextFormattedCitation":"[27,58–62]","previouslyFormattedCitation":"[27,58–62]"},"properties":{"noteIndex":0},"schema":""}[27,58–62]. With the increase of acoustic pressure, cavitation bubbles change from stable volume and shape oscillation to transient bubble collapse, generating liquid microstreaming, jets and shock waves. These physical effects have been widely applied to intensify mass transfer processes, such as cleaning, mixing, emulsification and extraction. On the other hand, the violent bubble collapse generate enormous temperatures and high pressure changes at a localized level, which produce radical or radical-ion intermediates that can react with reactants and thus accelerate some reactions. The oscillating intensity of cavitation bubble also depends on the bubble size and ultrasound frequency. For the frequency (f), the size of bubbles that have the strongest cavitation phenomena is usually near the linear resonance radius (Rr):Rr=12πf2γPhρ,(1)where γ=CpCv is the ratio of the specific heat of the gas at a constant pressure to its specific heat at a constant volume, ρ is the density of liquid and Ph is the hydrostatic liquid pressure ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"ISSN":"08146039","abstract":"The principal method behind applications of power ultrasound is that of acoustic cavitation. This paper aims to provide an overview of bubble behaviour during acoustic cavitation, including phenomena such as transient and stable cavitation, rectified diffusion, coalescence and sonoluminescence. Application of these effects to processes such as nanomaterial synthesis, emulsion formation and waste water treatment is then described.","author":[{"dropping-particle":"","family":"Leong","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ashokkumar","given":"Muthupandian","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sandra","given":"Kentish","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Acoustics Australia","id":"ITEM-1","issue":"2","issued":{"date-parts":[["2011"]]},"page":"54-63","title":"The fundamentals of power ultrasound - A review","type":"article-journal","volume":"39"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1088/0034-4885/73/10/106501","ISSN":"00344885","abstract":"Bubbles in liquids, soft and squeezy objects made of gas and vapour, yet so strong as to destroy any material and so mysterious as at times turning into tiny light bulbs, are the topic of the present report. Bubbles respond to pressure forces and reveal their full potential when periodically driven by sound waves. The basic equations for nonlinear bubble oscillation in sound fields are given, together with a survey of typical solutions. A bubble in a liquid can be considered as a representative example from nonlinear dynamical systems theory with its resonances, multiple attractors with their basins, bifurcations to chaos and not yet fully describable behaviour due to infinite complexity. Three stability conditions are treated for stable trapping of bubbles in standing sound fields: positional, spherical and diffusional stability. Chemical reactions may become important in that respect, when reacting gases fill the bubble, but the chemistry of bubbles is just touched upon and is beyond the scope of the present report. Bubble collapse, the runaway shrinking of a bubble, is presented in its current state of knowledge. Pressures and temperatures that are reached at this occasion are discussed, as well as the light emission in the form of short flashes. Aspherical bubble collapse, as for instance enforced by boundaries nearby, mitigates most of the phenomena encountered in spherical collapse, but introduces a new effect: jet formation, the self-piercing of a bubble with a high velocity liquid jet. Examples of this phenomenon are given from light induced bubbles. Two oscillating bubbles attract or repel each other, depending on their oscillations and their distance. Upon approaching, attraction may change to repulsion and vice versa. When being close, they also shoot self-piercing jets at each other. Systems of bubbles are treated as they appear after shock wave passage through a liquid and with their branched filaments that they attain in standing sound fields. The N-bubble problem is formulated in the spirit of the n-body problem of astrophysics, but with more complicated interaction forces. Simulations are compared with three-dimensional bubble dynamics obtained by stereoscopic high speed digital videography. ? 2010 IOP Publishing Ltd.","author":[{"dropping-particle":"","family":"Lauterborn","given":"Werner","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kurz","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Reports on Progress in Physics","id":"ITEM-2","issued":{"date-parts":[["2010"]]},"page":"1-88","title":"Physics of bubble oscillations","type":"article-journal","volume":"73"},"uris":[""]}],"mendeley":{"formattedCitation":"[61,63]","plainTextFormattedCitation":"[61,63]","previouslyFormattedCitation":"[61,63]"},"properties":{"noteIndex":0},"schema":""}[61,63]. For air bubbles in water, the estimated resonance size is represented in Figure 1c for a frequency range of 20 kHz– to 1 MHz.Figure 2. Effect of bubble radius on their cavitation behavior under ultrasound at a frequency of 20 kHz and a load power of 20 W. Bubble cavitation behavior was observed using a high-speed camera at an interval of 12.5 ?s, equaling to a quarter of ultrasound oscillating period. Reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]}],"mendeley":{"formattedCitation":"[24]","plainTextFormattedCitation":"[24]","previouslyFormattedCitation":"[24]"},"properties":{"noteIndex":0},"schema":""}[24], copyright John Wiley and Sons.Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]}],"mendeley":{"formattedCitation":"[24]","plainTextFormattedCitation":"[24]","previouslyFormattedCitation":"[24]"},"properties":{"noteIndex":0},"schema":""}[24] characterized the cavitation behavior of bubbles with different radii in microchannels in a ultrasound field of 20 kHz, as shown in Figure 2. With the increase of bubble size, the bubble oscillation changes from volume to shape oscillations, and finally turns into transient cavitation when the bubble radius approaches the resonance size (150 ?m in water). Bubbles larger than the resonance size undergo shape oscillations with dramatic surface wave distortion, resulting in strong microstreaming around it. This cavitation microstreaming is the steady flow formed due to the dissipation of acoustic energy near an oscillating bubble, this along with the rapid motion of cavitation bubbles can result in complex flow patterns ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c2lc40203c","ISSN":"14730189","abstract":"In part 14 of the tutorial series \"Acoustofluidics - exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation\", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Wiklund","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Green","given":"Roy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohlin","given":"Mathias","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issue":"14","issued":{"date-parts":[["2012"]]},"page":"2438-2451","title":"Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultras.2009.10.002","ISSN":"0041624X","abstract":"Cavitation microstreaming plays a role in the therapeutic action of microbubbles driven by ultrasound, such as the sonoporative and sonothrombolytic phenomena. Microscopic particle-image velocimetry experiments are presented. Results show that many different microstreaming patterns are possible around a microbubble when it is on a surface, albeit for microbubbles much larger than used in clinical practice. Each pattern is associated with a particular oscillation mode of the bubble, and changing between patterns is achieved by changing the sound frequency. Each microstreaming pattern also generates different shear stress and stretch/compression distributions in the vicinity of a bubble on a wall. Analysis of the micro-PIV results also shows that ultrasound-driven microstreaming flows around bubbles are feasible mechanisms for mixing therapeutic agents into the surrounding blood, as well as assisting sonoporative delivery of molecules across cell membranes. Patterns show significant variations around the bubble, suggesting sonoporation may be either enhanced or inhibited in different zones across a cellular surface. Thus, alternating the patterns may result in improved sonoporation and sonothrombolysis. The clear and reproducible delineation of microstreaming patterns based on driving frequency makes frequency-based pattern alternation a feasible alternative to the clinically less desirable practice of increasing sound pressure for equivalent sonoporative or sonothrombolytic effect. Surface divergence is proposed as a measure relevant to sonoporation. Crown Copyright ? 2009.","author":[{"dropping-particle":"","family":"Collis","given":"James","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Manasseh","given":"Richard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liovic","given":"Petar","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tho","given":"Paul","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ooi","given":"Andrew","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Petkovic-Duran","given":"Karolina","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhu","given":"Yonggang","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-2","issued":{"date-parts":[["2010"]]},"page":"273-279","publisher":"Elsevier B.V.","title":"Cavitation microstreaming and stress fields created by microbubbles","type":"article-journal","volume":"50"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.3390/fluids3040093","ISSN":"23115521","abstract":"Acoustic streaming is the steady flow of a fluid that is caused by the propagation of sound through that fluid. The fluid flow in acoustic streaming is generated by a nonlinear, time-averaged effect that results from the spatial and temporal variations in a pressure field. When there is an oscillating body submerged in the fluid, such as a cavitation bubble, vorticity is generated on the boundary layer on its surface, resulting in microstreaming. Although the effects are generated at the microscale, microstreaming can have a profound influence on the fluid mechanics of ultrasound/acoustic processing systems, which are of high interest to sonochemistry, sonoprocessing, and acoustophoretic applications. The effects of microstreaming have been evaluated over the years using carefully controlled experiments that identify and quantify the fluid motion at a small scale. This mini-review article overviews the historical development of acoustic streaming, shows how microstreaming behaves, and provides an update on new numerical and experimental studies that seek to explore and improve our understanding of microstreaming.","author":[{"dropping-particle":"","family":"Jalal","given":"Javeria","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Leong","given":"Thomas S.H.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Fluids","id":"ITEM-3","issue":"93","issued":{"date-parts":[["2018"]]},"page":"1-13","title":"Microstreaming and Its Role in Applications: A Mini-Review","type":"article-journal","volume":"3"},"uris":[""]}],"mendeley":{"formattedCitation":"[50,64,65]","plainTextFormattedCitation":"[50,64,65]","previouslyFormattedCitation":"[50,64,65]"},"properties":{"noteIndex":0},"schema":""}[50,64,65]. These flow patterns improve liquid mixing and accelerate gas–-liquid mass transfer, which will be discussed in detail in section 4.An important phenomenon observed in microreactors is the confinement effect ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-1","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2006.10.013","ISSN":"13504177","abstract":"Dynamic motions of gas bubble confined in a microspace, i.e., in a channel of a microreactor, were observed with a video microscope and stroboscopic technique using a light emitting diode operated in a pulsed mode. There are many important phenomena related to the bubble dynamics synchronized with ultrasonic wave and continued for more than a few minutes. With the stroboscopic technique, the time-expanded bubble motions synchronized with ultrasound wave and the real time background images can be simultaneously observed. A number of interesting phenomena resulting from the dynamic motions of a microbubble in a microspace were observed; nonspherical bubble oscillation, rectified diffusion, emergence of cavitation, and microstreaming of different patterns depending on the input power of ultrasound. The observation technique described in this investigation could be a convenient tool for taming the bubble under a microscope to investigate the bubble dynamics in detail. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Iida","given":"Yasuo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tuziuti","given":"Toru","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yasui","given":"Kyuichi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Towata","given":"Atsuya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kozuka","given":"Teruyuki","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2007"]]},"page":"621-626","title":"Bubble motions confined in a microspace observed with stroboscopic technique","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.cej.2019.05.157","ISSN":"13858947","abstract":"Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qiang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-3","issue":"April","issued":{"date-parts":[["2019"]]},"page":"68-78","publisher":"Elsevier","title":"Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature","type":"article-journal","volume":"374"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1039/b410015h","abstract":"Ultrasound was irradiated to a micro-1D and -2D space having a characteristic length of 200 mm, and the presence of cavitation was confirmed from video images, and the generation of OH radicals, which was quantitatively evaluated with fluorometry. Microspace","author":[{"dropping-particle":"","family":"Iida","given":"Yasuo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yasui","given":"Kyuichi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tuziuti","given":"Toru","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sivakumar","given":"Manickam","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Endo","given":"Yoshishige","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chem. Commun.","id":"ITEM-4","issued":{"date-parts":[["2004"]]},"page":"2280-2281","title":"Ultrasonic cavitation in microspace","type":"article-journal"},"uris":[""]}],"mendeley":{"formattedCitation":"[38,66–68]","plainTextFormattedCitation":"[38,66–68]","previouslyFormattedCitation":"[38,66–68]"},"properties":{"noteIndex":0},"schema":""}[38,66–68]. It was reported that cavitation phenomena in small microchannels are generally weaker than that in larger channels under the same ultrasound field. This is because smaller microchannels confine cavitation bubbles in a limited space, which produces a larger viscous resistance when bubbles oscillate. Zhao et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.05.157","ISSN":"13858947","abstract":"Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qiang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"April","issued":{"date-parts":[["2019"]]},"page":"68-78","publisher":"Elsevier","title":"Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature","type":"article-journal","volume":"374"},"uris":[""]}],"mendeley":{"formattedCitation":"[67]","plainTextFormattedCitation":"[67]","previouslyFormattedCitation":"[67]"},"properties":{"noteIndex":0},"schema":""}[67] compared the cavitation activity of various bubbles in five square microchannels with size ranging from 0.5 to 2.5 mm. Cavitation activity was reduced when the channel size was decreased from 1 mm to 0.5 mm, while no significant difference was observed in channels larger than 1 mm. This implies that 1 mm is the critical channel size above which the confinement effect disappears. Besides the confinement effect, the hydrodynamic pressure drop in small channels is higher than in larger channels when operated at the same flow rate, this could also weaken the cavitation activity.Due to the limited number of cavitation nuclei in the liquid, improving cavitation activity is an important topic for both continuous and batch reactor. Thanks Due to the same size range of microchannels and cavitation bubbles, artificial bubbles can be easily introduced into a microchannel ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c2cc33920j","ISSN":"13597345","abstract":"Microfluidics enable the manipulation of chemical reactions using very small amounts of fluid, in channels with dimensions of tens to hundreds of micrometers; so-called microstructured devices, from which the iconic image of chips emerges. The immediate attraction of microfluidics lies in its greenness: use of small quantities of reagents and solvents, and hence less waste, a precise control of reaction conditions, integration of functionality for process intensification, safer and often faster protocols, reliable scale-up, and possibility of performing multiphase reactions. Among the limitations found in microfluidics the facile formation of precipitating products should be highlighted, and in this context, the search for efficient mass and energy transfers is a must. Such limitations have been partially overcome with the aid of ultrasound in conventional flow systems, and can now be successfully used in microreactors, which provide new capabilities. Novel applications and a better understanding of the physical and chemical aspects of sonochemistry can certainly be achieved by combining microfluidics and ultrasound. We will review this nascent area of research, paying attention to the latest developments and showing future directions, which benefit both from the existing microfluidic technology and sonochemistry itself. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cintas","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Communications","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"10935-10947","title":"Merging microfluidics and sonochemistry: Towards greener and more efficient micro-sono-reactors","type":"article-journal","volume":"48"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-2","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ces.2018.04.042","ISSN":"00092509","abstract":"The synergistic effects of gas agitation and ultrasound on mass transfer between immiscible liquids were investigated in an in-house made ultrasonic microreactor. With the introduction of inert gas (N2), a three-phase slug flow with slug bubbles either dispersed in continuous aqueous phase or encapsulated in oil plugs was observed. Under ultrasound irradiation, slug bubbles underwent surface wave oscillation and induced agitation in microchannel. In addition, microbubbles were generated by acoustic cavitation, oscillating intensely and resulting in the formation of O/W emulsion. Bubble oscillation (i.e., slug bubbles and microbubbles) as well as emulsification promoted liquid-liquid mass transfer significantly. Extraction of vanillin from aqueous solution to toluene was employed to demonstrate the mass transfer enhancement. Compared with silent operation, both mass transfer coefficient and extraction efficiency were largely improved by the combined use of gas agitation and ultrasound. With gas flow velocity being 0.005–0.083 m/s at fixed ultrasound power of 30 W, the overall mass transfer coefficients ranged from 0.047 s?1 to 0.429 s?1, which was 2.33–17.20 times larger than the corresponding liquid-liquid two-phase process without ultrasound irradiation.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Yanyan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-3","issued":{"date-parts":[["2018"]]},"page":"122-134","publisher":"Elsevier Ltd","title":"Intensification of liquid-liquid two-phase mass transfer by oscillating bubbles in ultrasonic microreactor","type":"article-journal","volume":"186"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1002/anie.201005533","ISSN":"14337851","abstract":"It's the pits: Increased efficiency and controllability of sonochemical reactions was achieved with silicon surfaces on which pits were micromachined to entrap gas, which, upon ultrasonic excitation, emits a stream of microbubbles (see picture). The microbubbles are chemically active at ultrasonic amplitudes well below those necessary for sonochemical activity in conventional reactors. Copyright ? 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Prosperetti","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zijlstra","given":"Aaldert G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lohse","given":"Detlef","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Angewandte Chemie - International Edition","id":"ITEM-4","issue":"50","issued":{"date-parts":[["2010"]]},"page":"9699-9701","title":"Efficient Sonochemistry through Microbubbles Generated with Micromachined Surfaces","type":"article-journal","volume":"49"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1016/j.ultsonch.2012.07.024","ISSN":"18732828","abstract":"We describe the ejection of bubbles from air-filled pits micromachined on a silicon surface when exposed to ultrasound at a frequency of approximately 200 kHz. As the pressure amplitude is increased the bubbles ejected from the micropits tend to be larger and they interact in complex ways. With more than one pit, there is a threshold pressure beyond which the bubbles follow a trajectory parallel to the substrate surface and converge at the center point of the pit array. We have determined the size distribution of bubbles ejected from one, two and three pits, for three different pressure amplitudes and correlated them with sonochemical OH? radical production. Experimental evidence of shock wave emission from the bubble clusters, deformed bubble shapes and jetting events that might lead to surface erosion are presented. We describe numerical simulations of sonochemical conversion using the empirical bubble size distributions, and compare the calculated values with experimental results. ? 2012 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stricker","given":"Laura","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zijlstra","given":"Aaldert G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lohse","given":"Detlef","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Prosperetti","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-5","issued":{"date-parts":[["2013"]]},"page":"510-524","publisher":"Elsevier B.V.","title":"Ultrasound artificially nucleated bubbles and their sonochemical radical production","type":"article-journal","volume":"20"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1039/c5lc00247h","ISSN":"14730189","abstract":"Mixing two fluids together within a microfluidic device still remains a challenging operation today. In order to achieve this goal, a number of effective micromixers have been developed over the years based on the use of either passive or active systems. Typically, passive mixers require no external energy, are more robust, and are easy to manufacture albeit they are poorly flexible. Active mixers, on the other hand, rely on external disturbance and are thus more difficult to use but are proven to have greater efficacy. Here, we report a particularly effective, remotely induced and switchable microfluidic mixer, which relies on the concomitant use of ultrasound and a perfluorocarbon (PFC) phase, with the latter benefiting from its immiscibility with most fluids and its low boiling point. More specifically, our approach is based on localized vaporization of a PFC phase at the focal zone of a transducer leading to efficient mixing of two adjacent fluids. The results show that mixing occurs ~100 ms following the delivery of the acoustic pulse, while a laminar flow is re-established on roughly the same time scale. Overall, this method is simple and effective, does not require tailored channel geometries, is compatible with both hydrophilic and hydrophobic microfluidic systems, and is applicable to a wide range of Reynolds numbers (10-4 < Re < 2.100), and the PFC phase can be easily separated from the mixed phase at the end of the run.","author":[{"dropping-particle":"","family":"Bezagu","given":"Marine","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Arseniyadis","given":"Stellios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cossy","given":"Janine","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Couture","given":"Olivier","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tanter","given":"Mickael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Monti","given":"Fabrice","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tabeling","given":"Patrick","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-6","issued":{"date-parts":[["2015"]]},"page":"2025-2029","publisher":"Royal Society of Chemistry","title":"A fast and switchable microfluidic mixer based on ultrasound-induced vaporization of perfluorocarbon","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[35,38,39,56,69,70]","plainTextFormattedCitation":"[35,38,39,56,69,70]","previouslyFormattedCitation":"[35,38,39,56,69,70]"},"properties":{"noteIndex":0},"schema":""}[35,38,39,56,69,70]. The most common method is to fabricate micro-holes or grooves into the channel, which will trap bubbles of a specific size and initiate cavitation nuclei when ultrasound is turned on ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/b903687c","ISSN":"14730189","abstract":"We present ultra-fast homogeneous mixing inside a microfluidic channel via single-bubble-based acoustic streaming. The device operates by trapping an air bubble within a \"horse-shoe\" structure located between two laminar flows inside a microchannel. Acoustic waves excite the trapped air bubble at its resonance frequency, resulting in acoustic streaming, which disrupts the laminar flows and triggers the two fluids to mix. Due to this technique's simple design, excellent mixing performance, and fast mixing speed (a few milliseconds), our single-bubble-based acoustic micromixer may prove useful for many biochemical studies and applications. ? 2009 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mao","given":"Xiaole","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Shi","given":"Jinjie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Juluri","given":"Bala Krishna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Huang","given":"Tony Jun","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"2738-2741","title":"A millisecond micromixer via single-bubble-based acoustic streaming","type":"article-journal","volume":"9"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/anie.201005533","ISSN":"14337851","abstract":"It's the pits: Increased efficiency and controllability of sonochemical reactions was achieved with silicon surfaces on which pits were micromachined to entrap gas, which, upon ultrasonic excitation, emits a stream of microbubbles (see picture). The microbubbles are chemically active at ultrasonic amplitudes well below those necessary for sonochemical activity in conventional reactors. Copyright ? 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Prosperetti","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zijlstra","given":"Aaldert G.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lohse","given":"Detlef","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gardeniers","given":"Han J.G.E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Angewandte Chemie - International Edition","id":"ITEM-2","issue":"50","issued":{"date-parts":[["2010"]]},"page":"9699-9701","title":"Efficient Sonochemistry through Microbubbles Generated with Micromachined Surfaces","type":"article-journal","volume":"49"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1007/s10404-009-0444-3","ISSN":"16134982","abstract":"Due to the low Reynolds number associated with microscale fluid flow, it is difficult to rapidly and homogenously mix two fluids. In this letter, we report a fast and homogenized mixing device through the use of a bubble-based microfluidic structure. This micromixing device worked by trapping air bubbles within the pre-designed grooves on the sidewalls of the channel. When acoustically driven, the membranes (liquid/air interfaces) of these trapped bubbles started to oscillate. The bubble oscillation resulted in a microstreaming phenomenon-strong pressure and velocity fluctuations in the bulk liquid, thus giving rise to fast and homogenized mixing of two side-by-side flowing fluids. The performance of the mixer was characterized by mixing deionized water and ink at different flow rates. The mixing time was measured to be as small as 120 ms. ? 2009 Springer-Verlag.","author":[{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mao","given":"Xiaole","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Krishna Juluri","given":"Bala","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Microfluidics and Nanofluidics","id":"ITEM-3","issued":{"date-parts":[["2009"]]},"page":"727-731","title":"A fast microfluidic mixer based on acoustically driven sidewall-trapped microbubbles","type":"article-journal","volume":"7"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1039/c2lc40424a","ISSN":"14730189","abstract":"With the fast development of acoustic and multiphase microfluidics in recent years, oscillating bubbles have drawn more-and-more attention due to their great potential in various Lab on a Chip (LOC) applications. Many innovative bubble-based devices have been explored in the past decade. In this article, we first briefly summarize current understanding of the physics of oscillating bubbles, and then critically summarize recent advancements, including some of our original work, on the applications of oscillating bubbles in microfluidic devices. We intend to highlight the advantages of using oscillating bubbles along with the challenges that accompany them. We believe that these emerging studies on microfluidic oscillating bubbles will be revolutionary to the development of next-generation LOC technologies. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Hashmi","given":"Ali","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yu","given":"Gan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Reilly-Collette","given":"Marina","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heiman","given":"Garrett","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-4","issued":{"date-parts":[["2012"]]},"page":"4216-4227","title":"Oscillating bubbles: a versatile tool for lab on a chip applications","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[37,69,71,72]","plainTextFormattedCitation":"[37,69,71,72]","previouslyFormattedCitation":"[37,69,71,72]"},"properties":{"noteIndex":0},"schema":""}[37,69,71,72]. Tovar et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/b812435c","ISSN":"14730189","abstract":"The lateral cavity acoustic transducer (LCAT) is a novel microfluidic actuator designed to carry out diverse functions such as microfluidic pumping, mixing, and particle trapping. The device uses simple fabrication and operational procedures which lends itself for easy integration into current Lab-on-a-chip designs.","author":[{"dropping-particle":"","family":"Tovar","given":"Armando R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lee","given":"Abraham P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"41-43","title":"Lateral cavity acoustic transducer","type":"article-journal"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1007/s10404-010-0758-1","ISSN":"16134982","abstract":"An acoustically activated micropump is fabricated and demonstrated using a single step lithography process and an off-chip acoustic energy source. Using angled lateral cavities with trapped air bubbles, acoustic energy is used to oscillate the liquid-air interface to create a fluidic driving force. The angled lateral cavity design allows for fluid rectification from the first-order pulsatile flow of the oscillating bubbles. The fluid rectification is achieved through the asymmetrical flow produced by the oscillating interface generating fluid flow away from the lateral cavity interface. Simulation and experimental results are used to develop a pumping mechanism that is capable of driving fluid at pressures of 350 Pa. This pumping system is then integrated into a stand-alone battery operated system to drive fluid from one chip to another. ? 2011 The Author(s).","author":[{"dropping-particle":"","family":"Tovar","given":"Armando R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Patel","given":"Maulik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lee","given":"Abraham P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Microfluidics and Nanofluidics","id":"ITEM-2","issued":{"date-parts":[["2011"]]},"page":"1269-1278","title":"Lateral air cavities for microfluidic pumping with the use of acoustic energy","type":"article-journal","volume":"10"},"uris":[""]}],"mendeley":{"formattedCitation":"[73,74]","plainTextFormattedCitation":"[73,74]","previouslyFormattedCitation":"[73,74]"},"properties":{"noteIndex":0},"schema":""}[73,74] proposed the concept of ‘side cavity acoustic driver’, that is, chambers or grooves, processed in the sidewall of the channel that trap bubbles when the liquid enters. When ultrasound with a frequency close to the resonance frequency of the bubbles is applied, intense cavitation phenomena are generated, which then can mix and even pump fluids. Ozcelik et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/ac5007798","ISSN":"15206882","abstract":"During the deep reactive ion etching process, the sidewalls of a silicon mold feature rough wavy structures, which can be transferredontoapolydimethylsiloxane (PDMS) microchannel through the soft lithography technique. In this article, we utilized the wavy structures ofPDMS microchannel sidewalls to initiate and cavitate bubbles in the presence of acoustic waves. Through bubble cavitation, this acoustofluidic approach demonstrates fast, effective mixing in microfluidics. We characterized its performance by using viscous fluids such as poly(ethylene glycol) (PEG). When two PEG solutions with a resultant viscosity 54.9 times higher than that of water were used, the mixing efficiency was found to be 0.92, indicating excellent, homogeneous mixing. The acoustofluidic micromixer presented here has the advantages of simple fabrication, easy integration, and capability to mix high-viscosity fluids (Reynolds number: ～0.01) in less than 100 ms.","author":[{"dropping-particle":"","family":"Ozcelik","given":"Adem","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xie","given":"Yuliang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nama","given":"Nitesh","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Qu","given":"Zhiguo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ahsan Nawaz","given":"Ahmad","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Analytical Chemistry","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"5083-5088","publisher":"Americal Chemical Society","title":"An Acousto?uidic Micromixer via Bubble Inception and Cavitation from Microchannel Sidewalls","type":"article-journal","volume":"86"},"uris":[""]}],"mendeley":{"formattedCitation":"[75]","plainTextFormattedCitation":"[75]","previouslyFormattedCitation":"[75]"},"properties":{"noteIndex":0},"schema":""}[75] found that, by fabricating a rough wavy surface into the microchannel wall, the surface initiates cavitation bubbles in the presence of acoustic waves, producing fast and effective mixing. Injecting a stream of gas bubble into the microchannel also improves cavitation activity. Tandiono et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c002363a","ISSN":"14730189","abstract":"We present a study on achieving intense acoustic cavitation generated by ultrasonic vibrations in polydimethylsiloxane (PDMS) based microfluidic devices. The substrate to which the PDMS is bonded was forced into oscillation with a simple piezoelectric transducer attached at 5 mm from the device to a microscopic glass slide. The transducer was operated at 100 kHz with driving voltages ranging between 20 V and 230 V. Close to the glass surface, pressure and vibration amplitudes of up to 20 bar and 400 nm were measured respectively. It is found that this strong forcing leads to the excitation of nonlinear surface waves when gas-liquid interfaces are present in the microfluidic channels. Also, it is observed that nuclei leading to intense inertial cavitation are generated by the entrapment of gas pockets at those interfaces. Subsequently, cavitation bubble clusters with void fractions of more than 50% are recorded with high-speed photography at up to 250000 frames/s. The cavitation clusters can be sustained through the continuous injection of gas using a T-junction in the microfluidic device. ? The Royal Society of Chemistry 2010.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Siew-Wan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"Dave Siak-Wei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"Evert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wong","given":"Victor V.T.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Camattari","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Claus-Dieter","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2010"]]},"page":"1848-1855","title":"Creation of cavitation activity in a microfluidic device through acoustically driven capillary waves","type":"article-journal","volume":"10"},"uris":[""]}],"mendeley":{"formattedCitation":"[76,77]","plainTextFormattedCitation":"[76,77]","previouslyFormattedCitation":"[76,77]"},"properties":{"noteIndex":0},"schema":""}[76,77] investigated the effect of a 100 kHz ultrasonic field on gas–-liquid slug flow in a microchannel. Upon ultrasound application, the gas–-liquid interface vibrated violently, breaking up into a large number of bubble fragments, which then acted as cavitation nuclei for acoustic cavitation, producing a huge number of free radicals and intense light emissions. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-1","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]}],"mendeley":{"formattedCitation":"[38]","plainTextFormattedCitation":"[38]","previouslyFormattedCitation":"[38]"},"properties":{"noteIndex":0},"schema":""}[38] found that these strong cavitation phenomena on the gas–-liquid interface also accelerated the gas-liquid mass transfer significantly. This has led to the development of many applications that utilize this phenomenon, which is discussed in section 4.2.2. Standing acoustic waves in microchannels: Acoustophoretic force and streamingAs mentioned earlier for high frequency ultrasound, standing waves are often formed in microchannels as the corresponding wavelength approaches that of the channel height or width. Particles in a standing wave experience acoustic radiation forces that move particles either to the pressure node or antinode, known as acoustophoresis, see Figure 1a ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2014.02.016","ISSN":"18732828","PMID":"24629579","abstract":"Ultrasonic standing waves (USW) separation is an established technology for micro scale applications due to the excellent control to manipulate particles acoustically achieved when combining high frequency ultrasound with laminar flow in microchannels, allowing the development of numerous applications. Larger scale systems (pilot to industrial) are emerging; however, scaling up such processes are technologically very challenging. This paper reviews the physical principles that govern acoustic particle/droplet separation and the mathematical modeling techniques developed to understand, predict, and design acoustic separation processes. A further focus in this review is on acoustic streaming, which represents one of the major challenges in scaling up USW separation processes. The manuscript concludes by providing a brief overview of the state of the art of the technology applied in large scale systems with potential applications in the dairy and oil industries. ? 2014 Published by Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Trujillo","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Juliano","given":"Pablo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Barbosa-Cánovas","given":"Gustavo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Knoerzer","given":"Kai","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"2151-2164","publisher":"Elsevier B.V.","title":"Separation of suspensions and emulsions via ultrasonic standing waves - A review","type":"article-journal","volume":"21"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2lc21256k","ISSN":"14730189","abstract":"This acoustofluidics tutorial focuses on continuous flow-based half wavelength resonator systems operated in the transversal mode, where the direction of the primary acoustic force acts in plane with the microchip. The transversal actuation mode facilitates integration with up- and downstream microchannel networks as well as visual control of the acoustic focusing experiment. Applications of particle enrichment in an acoustic half wavelength resonator are discussed as well as clarification of the carrier fluid from undesired particles. Binary separation of particle/vesicle/cell mixtures into two subpopulations is outlined based on the different polarities of the acoustic contrast factor. Furthermore, continuous flow separation of different particle/cell types is described where both Free Flow Acoustophoresis (FFA) and binary acoustophoresis are utilized. By capitalizing on the laminar flow regime, acoustophoresis has proven especially successful in performing bead/cell translations between different buffer systems. Likewise, the ability to controllably translate particulate matter across streamlines has opened a route to valving of cells/particles without any moving parts, where event triggered cell sorting is becoming an increasing area of activity. Recent developments now also enable measurements of fundamental cell properties such as density and compressibility by means of acoustophoresis. General aspects on working with live cells in acoustophoresis systems are discussed as well as available means to quantify the outcome of cell and particle separation experiments performed by acoustophoresis. ? The Royal Society of Chemistry 2012.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Magnusson","given":"Cecilia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"1210-1223","title":"Acoustofluidics 8: Applications of acoustophoresis in continuous flow microsystems","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.bios.2006.08.023","ISSN":"09565663","abstract":"Direct radiation force (DRF) and acoustic streaming provide the main influences on the behaviour of particles in aqueous suspension in an ultrasound standing wave (USW). The direct radiation force, which drives suspended particles towards and concentrates them in acoustic pressure node planes, has been applied to rapidly transfer cells in small scale analytical separators. The DRF also significantly increased the sensitivity of latex agglutination test (LAT) by concentrating the particles of an analytical sample in the pressure node positions and hence greatly increasing the antibody-antigen encounter rate. Capture of biotinylated particles and spores on a coated acoustic reflector in a quarter wavelength USW resonator was DRF-enhanced by 70- and 100-fold, respectively compared to the situation in the absence of ultrasound. Acoustic streaming has been successfully employed for mixing small analytical samples. Cavitation micro-streaming substantially enhanced, through mixing, DNA hybridization and the capture efficiency of Escherichia coli K12 on the surface of immunomagnetic beads. Acoustic streaming induced in longitudinal standing wave and flexural plate wave immuno-sensors increased the detection of antigens by a factor of five and three times, respectively. Combined DRF and acoustic streaming effects enhanced the rate of the reaction between suspended mixture of cells and retroviruses. The examples of a biochip and an ultrasonic immuno-sensor implementing the DRF and acoustic streaming effects are also described in the review. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Kuznetsova","given":"Larisa A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coakley","given":"W. Terence","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biosensors and Bioelectronics","id":"ITEM-3","issued":{"date-parts":[["2007"]]},"page":"1567-1577","title":"Applications of ultrasound streaming and radiation force in biosensors","type":"article-journal","volume":"22"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultras.2014.08.003","ISSN":"0041624X","abstract":"Particle concentration and filtration is a key stage in a wide range of processing industries and also one that can be present challenges for high throughput, continuous operation. Here we demonstrate some features which increase the efficiency of ultrasound enhanced sedimentation and could enable the technology the potential to be scaled up. In this work, 20 mm piezoelectric plates were used to drive 100 mm high chambers formed from single structural elements. The coherent structural resonances were able to drive particles (yeast cells) in the water to nodes throughout the chamber. Ultrasound enhanced sedimentation was used to demonstrate the efficiency of the system (>99% particle clearance). Sub-wavelength pin protrusions were used for the contacts between the resonant chamber and other elements. The pins provided support and transferred power, replacing glue which is inefficient for power transfer. Filtration energies of ～4 J/ml of suspension were measured. A calculation of thermal convection indicates that the circulation could disrupt cell alignment in ducts >35 mm high when a 1 K temperature gradient is present; we predict higher efficiencies when this maximum height is observed. For the acoustic design, although modelling was minimal before construction, the very simple construction allowed us to form 3D models of the nodal patterns in the fluid and the duct structure. The models were compared with visual observations of particle movement, Chladni figures and scanning laser vibrometer mapping. This demonstrates that nodal planes in the fluid can be controlled by the position of clamping points and that the contacts could be positioned to increase the efficiency and reliability of particle manipulations in standing waves.","author":[{"dropping-particle":"","family":"Prest","given":"Jeff E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Treves Brown","given":"Bernard J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fielden","given":"Peter R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wilkinson","given":"Stephen J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hawkes","given":"Jeremy J.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-4","issued":{"date-parts":[["2015"]]},"page":"260-270","publisher":"Elsevier B.V.","title":"Scaling-up ultrasound standing wave enhanced sedimentation filters","type":"article-journal","volume":"56"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1039/b313493h","ISSN":"14730197","abstract":"A method to separate suspended particles from their medium in a continuous mode at microchip level is described. The method combines an ultrasonic standing wave field with the extreme laminar flow properties obtained in a silicon micro channel. The channel was 750 μm wide and 250 μm deep with vertical side walls defined by anisotropic wet etching. The suspension comprised \"Orgasol 5μm\" polyamide spheres and distilled water. The channel was perfused by applying an under pressure (suction) to the outlets. The channel was ultrasonically actuated from the back side of the chip by a piezoceramic plate. When operating the acoustic separator at the fundamental resonance frequency the acoustic forces were not strong enough to focus the particles into a well defined single band in the centre of the channel. The frequency was therefore changed to about 2 MHz, the first harmonic with two pressure nodes in the standing wave, and consequently two lines of particles were formed which were collected via the side outlets. Two different microchip separator designs were investigated with exit channels branching off from the separation channel at angles of 90° and 45° respectively. The 45° separator displayed the most optimal fluid dynamic properties and 90% of the particles were gathered in 2/3 of the original fluid volume.","author":[{"dropping-particle":"","family":"Nilsson","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Petersson","given":"Filip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nsson","given":"Henrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-5","issued":{"date-parts":[["2004"]]},"note":"Standing wave example","page":"131-135","title":"Acoustic control of suspended particles in micro fluidic chips","type":"article-journal","volume":"4"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1007/s10404-018-2094-9","ISBN":"0123456789","ISSN":"16134990","abstract":"? 2018, The Author(s). The aim of this paper is to study resonance conditions for acoustic particle focusing inside droplets in two-phase microfluidic systems. A bulk acoustic wave microfluidic chip was designed and fabricated for focusing microparticles inside aqueous droplets (plugs) surrounded by a continuous oil phase in a 380-μm-wide channel. The quality of the acoustic particle focusing was investigated by considering the influence of the acoustic properties of the continuous phase in relation to the dispersed phase. To simulate the system and study the acoustic radiation force on the particles inside droplets, a simplified 3D model was used. The resonance conditions and focusing quality were studied for two different cases: (1) the dispersed and continuous phases were acoustically mismatched (water droplets in fluorinated oil) and (2) the dispersed and continuous phases were acoustically matched (water droplets in olive oil). Experimentally, we observed poor acoustic particle focusing inside droplets surrounded by fluorinated oil while good focusing was observed in droplets surrounded by olive oil. The experimental results are supported qualitatively by our simulations. These show that the acoustic properties (density and compressibility) of the dispersed and continuous phases must be matched to generate a strong and homogeneous acoustic field inside the droplet that is suitable for high-quality intra-droplet acoustic particle focusing.","author":[{"dropping-particle":"","family":"Fornell","given":"Anna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Garofalo","given":"Fabio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bruus","given":"Henrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tenje","given":"Maria","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Microfluidics and Nanofluidics","id":"ITEM-6","issue":"75","issued":{"date-parts":[["2018"]]},"note":"Particle focusing in liquid droplet","page":"1-9","publisher":"Springer Berlin Heidelberg","title":"Intra-droplet acoustic particle focusing: simulations and experimental observations","type":"article-journal","volume":"22"},"uris":[""]}],"mendeley":{"formattedCitation":"[46–48,78–80]","plainTextFormattedCitation":"[46–48,78–80]","previouslyFormattedCitation":"[46–48,78–80]"},"properties":{"noteIndex":0},"schema":""}[46–48,78–80]. Particle movement is influenced by the acoustic contrast factor ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c1lc20996e","ISSN":"14730189","abstract":"Acoustophoresis is getting more attention as an effective and gentle non-contact method of manipulating cells and particles in microfluidic systems. A key to a successful assembly of an acoustophoresis system is a proper design of the acoustic resonator where aspects of fabrication techniques, material choice, thickness matching of involved components, as well as strategies of actuation, all have to be considered. This tutorial covers some of the basics in designing and building microfluidic acoustic resonators and will hopefully be a comprehensive and advisory document to assist the interested reader in creating a successful acoustophoretic device. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Evander","given":"Mikael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"684-695","title":"Acoustofluidics 5: Building microfluidic acoustic resonators","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/b601326k","ISSN":"03060012","abstract":"Acoustic standing wave technology combined with microtechnology opens up new areas for the development of advanced particle and cell separating microfluidic systems. This tutorial review outlines the fundamental work performed on continuous flow acoustic standing wave separation of particles in macro scale systems. The transition to the microchip format is further surveyed, where both fabrication and design issues are discussed. The acoustic technology offers attractive features, such as reasonable throughput and ability to separate particles in a size domain of about tenths of micrometers to tens of micrometers. Examples of different particle separation modes enabled in microfluidic chips, utilizing standing wave technology, are described along a discussion of several potential applications in life science research and in the medical clinic. Chip integrated acoustic standing wave separation technology is still in its infancy and it can be anticipated that new laboratory standards very well may emerge from the current research. ? The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Petersson","given":"Filip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Society Reviews","id":"ITEM-2","issued":{"date-parts":[["2007"]]},"note":"Standing wave, parameter","page":"492-506","title":"Chip integrated strategies for acoustic separation and manipulation of cells and particles","type":"article-journal","volume":"36"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1250/ast.37.221","ISSN":"13475177","abstract":"In this work, we demonstrate the possibility of focusing a stream of microparticles to generate a matrixlike distribution using bulk acoustic standing waves. To achieve this goal, an axial acoustic excitation was performed on a suspension of spherical quasi-monodisperse microparticles in a flow through minichannel with a square cross section of 2 mm × 2 mm. The pair of transducer elements was also used for stimulation at several frequencies corresponding to its theoretical eigenmodes. The generation of the matrixlike tree-dimensional (3D) structures of focused particles was achieved by reflections of the acoustic radiation force associated with the square geometry. Particle positions were recorded by interferometric digital holographic microscopy, and the corresponding normalized distribution in the cross section was calculated for each experimental setting. The focusing efficiency was investigated through the variation of the acoustic energy density induced by the voltage applied to the piezo part and the injected flow rate. The acoustic field was numerically computed and compared with the experimental positions of particles in the cross section of the channel.","author":[{"dropping-particle":"","family":"Perfetti","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saverio Iorio","given":"Carlo","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Acoustical Science and Technology","id":"ITEM-3","issue":"5","issued":{"date-parts":[["2016"]]},"note":"focusing efficiency: Standing wave","page":"221-230","title":"Three-dimensional matrixlike focusing of microparticles in flow through minichannel using acoustic standing waves: An experimental and modeling study","type":"article-journal","volume":"37"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.3390/cryst9030120","ISSN":"20734352","abstract":"Manipulation of high-density materials, such as crystals and liquid condensates, is of great importance for many applications, including serial crystallography, structural and molecular biology, chemistry, and medicine. In this work, we describe an acoustic technique to focus and harvest flowing crystals and liquid condensates. Moreover, we show, based on numerical simulations, that the acoustic waves can be used for size-based particle (crystals, droplets, etc.) separation. This is an essential technological step in biological research, medical applications, and industrial processes. The presented technology offers high precision, biocompatibility, ease of use and additionally, is non-invasive and inexpensive. With the recent advent of X-ray Free Electron Laser (XFEL) technology and the associated enormous importance of a thin jet of crystals, this technology might pave the way to a novel type of XFEL injector.","author":[{"dropping-particle":"","family":"Gelin","given":"Pierre","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lindt","given":"Joris","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bratek-Skicki","given":"Anna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stroobants","given":"Sander","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Krzek","given":"Marzena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ziemecka","given":"Iwona","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tompa","given":"Peter","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Malsche","given":"Wim","non-dropping-particle":"De","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Maes","given":"Dominique","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystals","id":"ITEM-4","issue":"120","issued":{"date-parts":[["2019"]]},"note":"focus crystals for online analysis.","page":"1-9","title":"Focusing of Microcrystals and Liquid Condensates in Acoustofluidics","type":"article-journal","volume":"9"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1007/s10404-018-2094-9","ISBN":"0123456789","ISSN":"16134990","abstract":"? 2018, The Author(s). The aim of this paper is to study resonance conditions for acoustic particle focusing inside droplets in two-phase microfluidic systems. A bulk acoustic wave microfluidic chip was designed and fabricated for focusing microparticles inside aqueous droplets (plugs) surrounded by a continuous oil phase in a 380-μm-wide channel. The quality of the acoustic particle focusing was investigated by considering the influence of the acoustic properties of the continuous phase in relation to the dispersed phase. To simulate the system and study the acoustic radiation force on the particles inside droplets, a simplified 3D model was used. The resonance conditions and focusing quality were studied for two different cases: (1) the dispersed and continuous phases were acoustically mismatched (water droplets in fluorinated oil) and (2) the dispersed and continuous phases were acoustically matched (water droplets in olive oil). Experimentally, we observed poor acoustic particle focusing inside droplets surrounded by fluorinated oil while good focusing was observed in droplets surrounded by olive oil. The experimental results are supported qualitatively by our simulations. These show that the acoustic properties (density and compressibility) of the dispersed and continuous phases must be matched to generate a strong and homogeneous acoustic field inside the droplet that is suitable for high-quality intra-droplet acoustic particle focusing.","author":[{"dropping-particle":"","family":"Fornell","given":"Anna","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Garofalo","given":"Fabio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bruus","given":"Henrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tenje","given":"Maria","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Microfluidics and Nanofluidics","id":"ITEM-5","issue":"75","issued":{"date-parts":[["2018"]]},"note":"Particle focusing in liquid droplet","page":"1-9","publisher":"Springer Berlin Heidelberg","title":"Intra-droplet acoustic particle focusing: simulations and experimental observations","type":"article-journal","volume":"22"},"uris":[""]}],"mendeley":{"formattedCitation":"[53,80–83]","plainTextFormattedCitation":"[53,80–83]","previouslyFormattedCitation":"[53,80–83]"},"properties":{"noteIndex":0},"schema":""}[53,80–83], which is a function of fluid and particle density, compressibility and the speed of sound in the mixture. The positive or negative contrast factor results in movement of particle to the node or antinode respectively and has been applied successfully to separate particles in a suspension into two fractions ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/b405748c","ISSN":"14730197","abstract":"Improved continuous acoustic particle separation (separation efficiency close to 100%) and separation of erythrocytes (red blood cells) from lipid microemboli in whole blood is reported.","author":[{"dropping-particle":"","family":"Petersson","given":"Filip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Holm","given":"Cecilia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nsson","given":"Henrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2005"]]},"note":"mentioned","page":"20-22","title":"Continuous separation of lipid particles from erythrocytes by means of laminar flow and acoustic standing wave forces","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1021/ac9013572","ISBN":"9780979806421","abstract":"An acoustic device for generating high quality blood plasma for PSA microarray diagnostics is presented. ? 2009 CBMS.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tajudin","given":"Asilah Ahmad","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?r?s","given":"Kerstin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sw?rd-Nilsson","given":"Ann Margaret","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"?berg","given":"Lena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Marko-Varga","given":"Gy?rgy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Malm","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lilja","given":"Hans","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Anal. Chem.","id":"ITEM-2","issued":{"date-parts":[["2009"]]},"note":"Standing wave example","page":"6030-6037","title":"Acoustic whole blood plasmapheresis chip for PSA microarray diagnostics","type":"article-journal","volume":"81"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.3791/53861","ISSN":"1940087X","abstract":"Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.","author":[{"dropping-particle":"","family":"Shields IV","given":"C. Wyatt","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cruz","given":"Daniela F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohiri","given":"Korine A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yellen","given":"Benjamin B.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lopez","given":"Gabriel P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Visualized Experiments","id":"ITEM-3","issued":{"date-parts":[["2016"]]},"note":"PIV Standing wave","page":"1-7","title":"Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles","type":"article-journal","volume":"109"},"uris":[""]}],"mendeley":{"formattedCitation":"[84–86]","plainTextFormattedCitation":"[84–86]","previouslyFormattedCitation":"[84–86]"},"properties":{"noteIndex":0},"schema":""}[84–86]. The magnitude of the radiation force on particles is proportional to the particle volume, and researchers have designed microfluidic channels to separate particles of different sizes with ease ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c1lc20996e","ISSN":"14730189","abstract":"Acoustophoresis is getting more attention as an effective and gentle non-contact method of manipulating cells and particles in microfluidic systems. A key to a successful assembly of an acoustophoresis system is a proper design of the acoustic resonator where aspects of fabrication techniques, material choice, thickness matching of involved components, as well as strategies of actuation, all have to be considered. This tutorial covers some of the basics in designing and building microfluidic acoustic resonators and will hopefully be a comprehensive and advisory document to assist the interested reader in creating a successful acoustophoretic device. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Evander","given":"Mikael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"684-695","title":"Acoustofluidics 5: Building microfluidic acoustic resonators","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/b405748c","ISSN":"14730197","abstract":"Improved continuous acoustic particle separation (separation efficiency close to 100%) and separation of erythrocytes (red blood cells) from lipid microemboli in whole blood is reported.","author":[{"dropping-particle":"","family":"Petersson","given":"Filip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Holm","given":"Cecilia","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nsson","given":"Henrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2005"]]},"note":"mentioned","page":"20-22","title":"Continuous separation of lipid particles from erythrocytes by means of laminar flow and acoustic standing wave forces","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1080/01496398508060702","ISSN":"0149-6395","author":[{"dropping-particle":"","family":"Giddings","given":"J Calvin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Separation Science and Technology","id":"ITEM-3","issue":"9-10","issued":{"date-parts":[["1985","11","1"]]},"note":"doi: 10.1080/01496398508060702","page":"749-768","publisher":"Taylor & Francis","title":"A System Based on Split-Flow Lateral-Transport Thin (SPLITT) Separation Cells for Rapid and Continuous Particle Fractionation","type":"article-journal","volume":"20"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1371/journal.pone.0023074","ISSN":"19326203","abstract":"Background: Excessive collection of platelets is an unwanted side effect in current centrifugation-based peripheral blood progenitor cell (PBPC) apheresis. We investigated a novel microchip-based acoustophoresis technique, utilizing ultrasonic standing wave forces for the removal of platelets from PBPC products. By applying an acoustic standing wave field onto a continuously flowing cell suspension in a micro channel, cells can be separated from the surrounding media depending on their physical properties. Study Design and Methods: PBPC samples were obtained from patients (n = 15) and healthy donors (n = 6) and sorted on an acoustophoresis-chip. The acoustic force was set to separate leukocytes from platelets into a target fraction and a waste fraction, respectively. The PBPC samples, the target and the waste fractions were analysed for cell recovery, purity and functionality. Results: The median separation efficiency of leukocytes to the target fraction was 98% whereas platelets were effectively depleted by 89%. PBPC samples and corresponding target fractions were similar in the percentage of CD34+ hematopoetic progenitor/stem cells as well as leukocyte/lymphocyte subset distributions. Median viability was 98%, 98% and 97% in the PBPC samples, the target and the waste fractions, respectively. Results from hematopoietic progenitor cell assays indicated a preserved colony-forming ability post-sorting. Evaluation of platelet activation by P-selectin (CD62P) expression revealed a significant increase of CD62P+ platelets in the target (19%) and waste fractions (20%), respectively, compared to the PBPC input samples (9%). However, activation was lower when compared to stored blood bank platelet concentrates (48%). Conclusion: Acoustophoresis can be utilized to efficiently deplete PBPC samples of platelets, whilst preserving the target stem/progenitor cell and leukocyte cell populations, cell viability and progenitor cell colony-forming ability. Acoustophoresis is, thus, an interesting technology to improve current cell processing methods. ? 2011 Dykes et al.","author":[{"dropping-particle":"","family":"Dykes","given":"Josefina","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"?strand-Grundstr?m","given":"Ing-Britt","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Scheding","given":"Stefan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"PLoS ONE","id":"ITEM-4","issue":"8","issued":{"date-parts":[["2011"]]},"page":"1-10","title":"Efficient Removal of Platelets from Peripheral Blood Progenitor Cell Products Using a Novel Micro-Chip Based Acoustophoretic Platform","type":"article-journal","volume":"6"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1039/c6lc00951d","ISSN":"14730189","abstract":"Herein, we have demonstrated coating of particles and cells utilizing the taSSAW approach.On-chip microparticle and cell coating technologies enable a myriad of applications in chemistry, engineering, and medicine. Current microfluidic coating technologies often rely on magnetic labeling and concurrent deflection of particles across laminar streams of chemicals. Herein, we introduce an acoustofluidic approach for microparticle and cell coating by implementing tilted-angle standing surface acoustic waves (taSSAWs) into microchannels with multiple inlets. The primary acoustic radiation force generated by the taSSAW field was exploited in order to migrate the particles across the microchannel through multiple laminar streams, which contained the buffer and coating chemicals. We demonstrate effective coating of polystyrene microparticles and HeLa cells without the need for magnetic labelling. We characterized the coated particles and HeLa cells with fluorescence microscopy and scanning electron microscopy. Our acoustofluidic-based particle and cell coating method is label-free, biocompatible, and simple. It can be useful in the on-chip manufacturing of many functional particles and cells.","author":[{"dropping-particle":"","family":"Ayan","given":"Bugra","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ozcelik","given":"Adem","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bachman","given":"Hunter","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tang","given":"Shi -Yang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xie","given":"Yuliang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wu","given":"Mengxi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Li","given":"Peng","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Huang","given":"Tony Jun","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-5","issued":{"date-parts":[["2016"]]},"note":"Standing wave application","page":"4366-4372","publisher":"Royal Society of Chemistry","title":"Acoustofluidic coating of particles and cells","type":"article-journal","volume":"16"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1121/1.1904405","abstract":"Acoustic particle manipulation has many potential uses in flow cytometry and microfluidic array applications. Currently, most ultrasonic particle positioning devices utilize a quasi-one-dimensional geometry to set up the positioning field. A transducer fit with a quarter-wave matching layer, locally drives a cavity of width one-half wavelength. Particles within the cavity experience a time-averaged drift force that transports them to a nodal position. Present research investigates an acoustic particle-positioning device where the acoustic excitation is generated by the entire structure, as opposed to a localized transducer. The lowest-order structural modes of a long cylindrical glass tube driven by a piezoceramic with a line contact are tuned, via material properties and aspect ratio, to match resonant modes of the fluid-filled cavity. The cylindrical geometry eliminates the need for accurate alignment of a transducer/reflector system, in contrast to the case of planar or confocal fields. Experiments show that the lower energy density in the cavity, brought about through excitation of the whole cylindrical tube, results in reduced cavitation, convection, and thermal gradients. The effects of excitation and material parameters on concentration quality are theoretically evaluated, using two-dimensional elastodynamic equations describing the fluid-filled cylindrical shell with a line excitation.","author":[{"dropping-particle":"","family":"Goddard","given":"Gregory","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kaduchak","given":"Gregory","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Acoustical Society of America","id":"ITEM-6","issued":{"date-parts":[["2005"]]},"note":"standing wave application","page":"3440-3447","title":"Ultrasonic particle concentration in a line-driven cylindrical tube","type":"article-journal","volume":"117"},"uris":[""]}],"mendeley":{"formattedCitation":"[81,84,87–90]","plainTextFormattedCitation":"[81,84,87–90]","previouslyFormattedCitation":"[81,84,87–90]"},"properties":{"noteIndex":0},"schema":""}[81,84,87–90]. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49] studied the effect of particle size on focusing effect in the microreactor and observed that bigger particles experience larger acoustophoretic force and are focused in shorter time, see Figure 3. This acoustophoretic effect also has the potential to overcome clogging issues by focusing particles to the channel center thus avoiding particle contact with channel walls ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.3390/s17010106","ISSN":"14248220","abstract":"??? 2017 by the authors; licensee MDPI, Basel, Switzerland. Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 ???m microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO 3 wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging.","author":[{"dropping-particle":"","family":"Sriphutkiat","given":"Yannapol","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhou","given":"Yufeng","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Sensors","id":"ITEM-2","issue":"106","issued":{"date-parts":[["2017"]]},"note":"Already Mentioned","page":"1-18","title":"Particle Accumulation in a Microchannel and Its Reduction by a Standing Surface Acoustic Wave (SSAW)","type":"article-journal","volume":"17"},"uris":[""]}],"mendeley":{"formattedCitation":"[49,54]","plainTextFormattedCitation":"[49,54]","previouslyFormattedCitation":"[49,54]"},"properties":{"noteIndex":0},"schema":""}[49,54]. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49] have successfully demonstrated the effectiveness of standing acoustic waves to prevent clogging in a microchannel.Figure 3. Focusing onf polystyrene particles in a microchannel by high frequency ultrasound (1.21 MHz and 15 Vpp) for different particle sizes (2–-10 ?m). The images in each row were taken at different channel positions with the channel length and thus residence time increasing from CH1 to CH5. Reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49], copyright Royal Society of Chemistry.Another phenomenon observed with high frequency ultrasound is acoustic streaming. The two major types of streaming, that can be observed as a result of standing waves are boundary layer streaming and Eckart streaming. Eckart streaming is observed for channel dimensions in the order of a few centimeters and is hence not typically found in microchannels ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.bios.2006.08.023","ISSN":"09565663","abstract":"Direct radiation force (DRF) and acoustic streaming provide the main influences on the behaviour of particles in aqueous suspension in an ultrasound standing wave (USW). The direct radiation force, which drives suspended particles towards and concentrates them in acoustic pressure node planes, has been applied to rapidly transfer cells in small scale analytical separators. The DRF also significantly increased the sensitivity of latex agglutination test (LAT) by concentrating the particles of an analytical sample in the pressure node positions and hence greatly increasing the antibody-antigen encounter rate. Capture of biotinylated particles and spores on a coated acoustic reflector in a quarter wavelength USW resonator was DRF-enhanced by 70- and 100-fold, respectively compared to the situation in the absence of ultrasound. Acoustic streaming has been successfully employed for mixing small analytical samples. Cavitation micro-streaming substantially enhanced, through mixing, DNA hybridization and the capture efficiency of Escherichia coli K12 on the surface of immunomagnetic beads. Acoustic streaming induced in longitudinal standing wave and flexural plate wave immuno-sensors increased the detection of antigens by a factor of five and three times, respectively. Combined DRF and acoustic streaming effects enhanced the rate of the reaction between suspended mixture of cells and retroviruses. The examples of a biochip and an ultrasonic immuno-sensor implementing the DRF and acoustic streaming effects are also described in the review. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Kuznetsova","given":"Larisa A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coakley","given":"W. Terence","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biosensors and Bioelectronics","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"1567-1577","title":"Applications of ultrasound streaming and radiation force in biosensors","type":"article-journal","volume":"22"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2lc40203c","ISSN":"14730189","abstract":"In part 14 of the tutorial series \"Acoustofluidics - exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation\", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Wiklund","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Green","given":"Roy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohlin","given":"Mathias","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issue":"14","issued":{"date-parts":[["2012"]]},"page":"2438-2451","title":"Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[48,50]","plainTextFormattedCitation":"[48,50]","previouslyFormattedCitation":"[48,50]"},"properties":{"noteIndex":0},"schema":""}[48,50]. Boundary layer streaming, on the other hand, which includes Schlichting and more importantly Rayleigh streaming, is the flow generated by the viscous dissipation of acoustic energy in the fluid boundary layer and is the main streaming phenomenon observed in microchannels ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.bios.2006.08.023","ISSN":"09565663","abstract":"Direct radiation force (DRF) and acoustic streaming provide the main influences on the behaviour of particles in aqueous suspension in an ultrasound standing wave (USW). The direct radiation force, which drives suspended particles towards and concentrates them in acoustic pressure node planes, has been applied to rapidly transfer cells in small scale analytical separators. The DRF also significantly increased the sensitivity of latex agglutination test (LAT) by concentrating the particles of an analytical sample in the pressure node positions and hence greatly increasing the antibody-antigen encounter rate. Capture of biotinylated particles and spores on a coated acoustic reflector in a quarter wavelength USW resonator was DRF-enhanced by 70- and 100-fold, respectively compared to the situation in the absence of ultrasound. Acoustic streaming has been successfully employed for mixing small analytical samples. Cavitation micro-streaming substantially enhanced, through mixing, DNA hybridization and the capture efficiency of Escherichia coli K12 on the surface of immunomagnetic beads. Acoustic streaming induced in longitudinal standing wave and flexural plate wave immuno-sensors increased the detection of antigens by a factor of five and three times, respectively. Combined DRF and acoustic streaming effects enhanced the rate of the reaction between suspended mixture of cells and retroviruses. The examples of a biochip and an ultrasonic immuno-sensor implementing the DRF and acoustic streaming effects are also described in the review. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Kuznetsova","given":"Larisa A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coakley","given":"W. Terence","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biosensors and Bioelectronics","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"1567-1577","title":"Applications of ultrasound streaming and radiation force in biosensors","type":"article-journal","volume":"22"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c2lc40203c","ISSN":"14730189","abstract":"In part 14 of the tutorial series \"Acoustofluidics - exploiting ultrasonic standing wave forces and acoustic streaming in microfluidic systems for cell and particle manipulation\", we provide a qualitative description of acoustic streaming and review its applications in lab-on-a-chip devices. The paper covers boundary layer driven streaming, including Schlichting and Rayleigh streaming, Eckart streaming in the bulk fluid, cavitation microstreaming and surface-acoustic-wave-driven streaming. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Wiklund","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Green","given":"Roy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohlin","given":"Mathias","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issue":"14","issued":{"date-parts":[["2012"]]},"page":"2438-2451","title":"Acoustofluidics 14: Applications of acoustic streaming in microfluidic devices","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[48,50]","plainTextFormattedCitation":"[48,50]","previouslyFormattedCitation":"[48,50]"},"properties":{"noteIndex":0},"schema":""}[48,50]. Bengtsson et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1007/s00216-003-2334-y","ISSN":"16182642","abstract":"This paper describes an acoustic method for inducing rotating vortex flows in microchannels. An ultrasonic crystal is used to create an acoustic standing wave field in the channel and thus induce a Rayleigh flow transverse to the laminar flow in the channel. Mixing in microchannels is strictly diffusion-limited because of the laminar flow, a transverse flow will greatly enhance mixing of the reactants. This is especially evident in chemical microsystems in which the chemical reaction is performed on a solid phase and only one reactant is actually diffusing. The method has been evaluated on two different systems, a mixing channel with two parallel flows and a porous silicon micro enzyme reactor for protein digestion. In both systems a significant increase of the mixing ratio is detected in a narrow band of frequency for the actuating ultrasound. ? Springer-Verlag 2004.","author":[{"dropping-particle":"","family":"Bengtsson","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Analytical and Bioanalytical Chemistry","id":"ITEM-1","issued":{"date-parts":[["2004"]]},"page":"1716-1721","title":"Ultrasonic agitation in microchannels","type":"article-journal","volume":"378"},"uris":[""]}],"mendeley":{"formattedCitation":"[91]","plainTextFormattedCitation":"[91]","previouslyFormattedCitation":"[91]"},"properties":{"noteIndex":0},"schema":""}[91] used Rayleigh streaming to improve mixing in microchannels. They also noticed that above a certain flow rate, Rayleigh streaming becomes less effective. Johansson et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/B815114H","ISSN":"1473-0197","abstract":"An acoustic mixer for glass channel microfluidic systems is presented. An acoustic standing wave, perpendicular to the fluid flow, is generated by the excitation of a miniaturized piezoelectric transducer operated around 10 MHz. The transducer is fabricated into a planar printed circuit board structure, constituting the bottom channel wall, which makes the mixer simple to integrate with a wide selection of microfluidic channel designs. The mixing occurs at a fluid-fluid density interface due to the acoustic radiation force; an analytical expression is derived to qualitatively describe this phenomenon. Only a small density difference in the range of 2–5% is required to achieve 150–270% peak broadening of a fluorescent sample between sheath flows, which we use as a measure of the mixing efficiency. The mixing efficiency is measured with regard to its sensitivity to the density difference, the fluid velocity and the transducer driving frequency. Transducers at different positions along the microchannel make it possible to compare the mixing of straight versus diagonal flows across the transducer surface. We finally demonstrate enhanced chemical lysis of E. coli K12 cells in the device due to active fluid mixing.","author":[{"dropping-particle":"","family":"Johansson","given":"Linda","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Johansson","given":"Stefan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nikolajeff","given":"Fredrik","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Thorslund","given":"Sara","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab Chip","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"297-304","title":"Effective mixing of laminar flows at a density interface by an integrated ultrasonic transducer","type":"article-journal","volume":"9"},"uris":[""]}],"mendeley":{"formattedCitation":"[92]","plainTextFormattedCitation":"[92]","previouslyFormattedCitation":"[92]"},"properties":{"noteIndex":0},"schema":""}[92] also observed an increase in the mixing efficiency of liquids with different densities on applications of standing wave in microchannels.3. Reactor fabricationContrary to the extensive literature on the mechanisms of ultrasound, less details on the design, fabrication and characterization of ultrasonic flow reactors have been reported. This section will classify the reported reactors into categories, and then summarize their advantages and drawbacks. Characterization methods to assist the reactor design are introduced subsequently.3.1. Reactor designUltrasonic flow reactors usually consist of an ultrasonic transducer and a microfluidic device. The transducer, typically based on piezoelectric materials, converts alternating current into ultrasonic vibrations. It is normally actuated by a power amplifier driven with a sine wave from a signal generator. Based on the type of transducer used, ultrasonic reactors can be classified as piezoelectric plate based reactors or Langevin-type transducer based reactors. 3.1.1. Piezoelectric plate based reactorPiezoelectric plate reactors can be built by directly coupling a piezoelectric plate to the surface of a microreactor. Often, the two parts are bonded together by epoxy glue ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1007/s10404-009-0444-3","ISSN":"16134982","abstract":"Due to the low Reynolds number associated with microscale fluid flow, it is difficult to rapidly and homogenously mix two fluids. In this letter, we report a fast and homogenized mixing device through the use of a bubble-based microfluidic structure. This micromixing device worked by trapping air bubbles within the pre-designed grooves on the sidewalls of the channel. When acoustically driven, the membranes (liquid/air interfaces) of these trapped bubbles started to oscillate. The bubble oscillation resulted in a microstreaming phenomenon-strong pressure and velocity fluctuations in the bulk liquid, thus giving rise to fast and homogenized mixing of two side-by-side flowing fluids. The performance of the mixer was characterized by mixing deionized water and ink at different flow rates. The mixing time was measured to be as small as 120 ms. ? 2009 Springer-Verlag.","author":[{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mao","given":"Xiaole","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Krishna Juluri","given":"Bala","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Microfluidics and Nanofluidics","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"727-731","title":"A fast microfluidic mixer based on acoustically driven sidewall-trapped microbubbles","type":"article-journal","volume":"7"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c1lc20996e","ISSN":"14730189","abstract":"Acoustophoresis is getting more attention as an effective and gentle non-contact method of manipulating cells and particles in microfluidic systems. A key to a successful assembly of an acoustophoresis system is a proper design of the acoustic resonator where aspects of fabrication techniques, material choice, thickness matching of involved components, as well as strategies of actuation, all have to be considered. This tutorial covers some of the basics in designing and building microfluidic acoustic resonators and will hopefully be a comprehensive and advisory document to assist the interested reader in creating a successful acoustophoretic device. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Evander","given":"Mikael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"684-695","title":"Acoustofluidics 5: Building microfluidic acoustic resonators","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[71,81]","plainTextFormattedCitation":"[71,81]","previouslyFormattedCitation":"[71,81]"},"properties":{"noteIndex":0},"schema":""}[71,81]. In some cases, at low ultrasonic power, the two parts can be clamped together with the use of transmission grease to ensure good contact between the plate and the reactor ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c1lc20337a","ISSN":"14730189","abstract":"We present a general inexpensive method for realizing a Teflon stack microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The microreactors are demonstrated with palladium-catalyzed C-N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. Investigations of the ultrasonic waveform applied by the piezoelectric actuator reveal an optimal value of 50 kHz at a load power of 30 W. Operating the system at these conditions, the newly developed Teflon microreactor handles the insoluble solids formed and no clogging is observed. The investigated reactions reach full conversion in very short reaction times and high isolated yields are obtained (>95% yield).","author":[{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heider","given":"Patrick L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"2488-2492","title":"A Teflon microreactor with integrated piezoelectric actuator to handle solid forming reactions","type":"article-journal","volume":"11"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultras.2014.08.003","ISSN":"0041624X","abstract":"Particle concentration and filtration is a key stage in a wide range of processing industries and also one that can be present challenges for high throughput, continuous operation. Here we demonstrate some features which increase the efficiency of ultrasound enhanced sedimentation and could enable the technology the potential to be scaled up. In this work, 20 mm piezoelectric plates were used to drive 100 mm high chambers formed from single structural elements. The coherent structural resonances were able to drive particles (yeast cells) in the water to nodes throughout the chamber. Ultrasound enhanced sedimentation was used to demonstrate the efficiency of the system (>99% particle clearance). Sub-wavelength pin protrusions were used for the contacts between the resonant chamber and other elements. The pins provided support and transferred power, replacing glue which is inefficient for power transfer. Filtration energies of ～4 J/ml of suspension were measured. A calculation of thermal convection indicates that the circulation could disrupt cell alignment in ducts >35 mm high when a 1 K temperature gradient is present; we predict higher efficiencies when this maximum height is observed. For the acoustic design, although modelling was minimal before construction, the very simple construction allowed us to form 3D models of the nodal patterns in the fluid and the duct structure. The models were compared with visual observations of particle movement, Chladni figures and scanning laser vibrometer mapping. This demonstrates that nodal planes in the fluid can be controlled by the position of clamping points and that the contacts could be positioned to increase the efficiency and reliability of particle manipulations in standing waves.","author":[{"dropping-particle":"","family":"Prest","given":"Jeff E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Treves Brown","given":"Bernard J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fielden","given":"Peter R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wilkinson","given":"Stephen J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hawkes","given":"Jeremy J.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"260-270","publisher":"Elsevier B.V.","title":"Scaling-up ultrasound standing wave enhanced sedimentation filters","type":"article-journal","volume":"56"},"uris":[""]}],"mendeley":{"formattedCitation":"[43,78]","plainTextFormattedCitation":"[43,78]","previouslyFormattedCitation":"[43,78]"},"properties":{"noteIndex":0},"schema":""}[43,78]. Although the ultrasound transmission efficiency of this method might be lower compared to the use of epoxy glue, it allows disassembly, reuse and replacement of the two parts. A piezoelectric plate transducer can work under different resonance modes allowing multiple resonance frequencies, at which the reactor has a higher energy transfer efficiency. For example, the reactor developed by Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[93]","plainTextFormattedCitation":"[93]","previouslyFormattedCitation":"[93]"},"properties":{"noteIndex":0},"schema":""}[93] consists of a piezoelectric plate with length, width and depth of 80 × 40 × 1.67 mm3 glued to the bottom of a silicon plate microreactor, see Figure 4a. The measured impedance curve shows that the reactor hads several resonance peaks, between 20 kHz and 2 MHz, corresponding to different vibration modes with the main resonance peak of the thickness vibration mode located at 1.2 MHz. Consequently, piezoelectric plate reactors can operate at both low and high frequencies. Furthermore, they are versatile, simple to fabricate and easy to operate, making them the most widely used ultrasonic flow reactors in academia. Especially for acoustofluidic applications, this reactor is normally designed as a layered resonator, in which the thickness of the piezoelectric plate, reactor layer and cover plate match either a half or a quarter wavelength, resulting in highly efficient resonance vibrations in the thickness direction ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c1lc20996e","ISSN":"14730189","abstract":"Acoustophoresis is getting more attention as an effective and gentle non-contact method of manipulating cells and particles in microfluidic systems. A key to a successful assembly of an acoustophoresis system is a proper design of the acoustic resonator where aspects of fabrication techniques, material choice, thickness matching of involved components, as well as strategies of actuation, all have to be considered. This tutorial covers some of the basics in designing and building microfluidic acoustic resonators and will hopefully be a comprehensive and advisory document to assist the interested reader in creating a successful acoustophoretic device. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Lenshof","given":"Andreas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Evander","given":"Mikael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Laurell","given":"Thomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nilsson","given":"Johan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"684-695","title":"Acoustofluidics 5: Building microfluidic acoustic resonators","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-2","itemData":{"abstract":"Separation of suspended particles by means of acoustic forces is a promising alternative to conventional technologies. This paper concerns some of the latest developments of separation devices based on piezoelectric resonators. The acoustic forces on particles suspended in a liquid are reviewed. A mathematical model for the description of layered piezoelectric resonators is extended and applied to the calculation of the electrical properties and the acoustic field quantities of the resonator. A resonator for particle separation is analyzed and the optimum operating frequency range with respect to resonator efficiency (performance number) is determined. It is found that efficiency depends strongly on the frequency and the properties of the suspension. Results are in good agreement with experimental data and with a different approach based on perturbation theory.","author":[{"dropping-particle":"","family":"Gr?schl","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Acustica","id":"ITEM-2","issued":{"date-parts":[["1998"]]},"page":"432-447","title":"Ultrasonic Separation of Suspended Particles - Part I: Fundamentals","type":"article-journal","volume":"84"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/S0041-624X(02)00127-0","ISSN":"0041624X","PMID":"12159971","abstract":"The potential of ultrasonic techniques for the separation and concentration of particles within a fluid has been investigated in some detail in recent years. Devices for effecting such separation typically consist of a piezoceramic transducer driving into a matching layer, fluid layer and reflector layer. This paper uses an equivalent-circuit transducer model, coupled with acoustic impedance transfer relationships to model such cells with regards to both their electrical characteristics and the strength of the resonance produced under different conditions. The model is compared with experimental results from two different cells and is shown to match experimental values well in terms of electrical characteristics and separator performance. The effects of matching layer thickness are also examined using the model. The importance of the adhesive bonding layer is demonstrated, and it is shown that the model can predict the effects of such a layer. The model is also used to demonstrate the effects of coincident resonances in cell layers and to examine the pressure distribution across cells at key frequencies. ? 2002 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Hill","given":"Martyn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Shen","given":"Yijun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hawkes","given":"Jeremy J.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-3","issued":{"date-parts":[["2002"]]},"page":"385-392","title":"Modelling of layered resonators for ultrasonic separation","type":"article-journal","volume":"40"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultras.2008.06.007","ISSN":"0041624X","abstract":"Several approaches have been described for the manipulation of particles within an ultrasonic field. Of those based on standing waves, devices in which the critical dimension of the resonant chamber is less than a wavelength are particularly well suited to microfluidic, or \"lab on a chip\" applications. These might include pre-processing or fractionation of samples prior to analysis, formation of monolayers for cell interaction studies, or the enhancement of biosensor detection capability. The small size of microfluidic resonators typically places tight tolerances on the positioning of the acoustic node, and such systems are required to have high transduction efficiencies, for reasons of power availability and temperature stability. Further, the expense of many microfabrication methods precludes an iterative experimental approach to their development. Hence, the ability to design sub-wavelength resonators that are efficient, robust and have the appropriate acoustic energy distribution is extremely important. This paper discusses one-dimensional modelling used in the design of ultrasonic resonators for particle manipulation and gives example of their uses to predict and explain resonator behaviour. Particular difficulties in designing quarter wave systems are highlighted, and modelling is used to explain observed trends and predict performance of such resonators, including their performance with different coupling layer materials. ? 2008 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Hill","given":"Martyn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Townsend","given":"Rosemary J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Harris","given":"Nicholas R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-4","issued":{"date-parts":[["2008"]]},"page":"521-528","publisher":"Elsevier B.V.","title":"Modelling for the robust design of layered resonators for ultrasonic particle manipulation","type":"article-journal","volume":"48"},"uris":[""]}],"mendeley":{"formattedCitation":"[81,94–96]","plainTextFormattedCitation":"[81,94–96]","previouslyFormattedCitation":"[81,94–96]"},"properties":{"noteIndex":0},"schema":""}[81,94–96]. However, the load power is limited due to the tensile strength limitations of the piezoelectric material.Figure 4. Representative examples of four categories of ultrasonic flow reactors. (a) Picture of a piezoelectric plate reactor developed by Dong et al., the reactor consists of a piezoelectric plate glued to the bottom of a silicon plate microreactor, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[93]","plainTextFormattedCitation":"[93]","previouslyFormattedCitation":"[93]"},"properties":{"noteIndex":0},"schema":""}[93], copyright Elsevier. (b) Capillary microreactor immersed in an ultrasonic bath, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2009.04.004","ISSN":"02552701","abstract":"In this work, the liquid-liquid catalytic phase transfer reaction between benzyl chloride with sodium sulfide was investigated in a capillary-microreactor assisted by ultrasound irradiation. A rational reaction mechanism was satisfactorily developed. The kinetics of the multiphase reaction was studied at different phase transfer catalyst concentration, sodium sulfide concentration and aqueous-to-organic phase flow rate ratio under both silent and sonication conditions. The reaction conversion was increased with an increase in the phase transfer catalyst concentration and sodium sulfide concentration under sonication conditions more profoundly than under silent conditions. Under sonication conditions, the reaction conversion was further enhanced by increasing the aqueous-to-organic phase flow rate ratio. However, under silent condition, such effect was negligible. In addition, the reaction system was studied in a mechanically stirred batch reactor under silent and sonication conditions. The reaction conversion was enhanced by increasing the agitation speed. The reaction conversion was further enhanced by the combination of mechanical agitation and ultrasound irradiation. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Aljbour","given":"Salah","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yamada","given":"Hiroshi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tagawa","given":"Tomohiko","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"1167-1172","title":"Ultrasound-assisted phase transfer catalysis in a capillary microreactor","type":"article-journal","volume":"48"},"uris":[""]}],"mendeley":{"formattedCitation":"[97]","plainTextFormattedCitation":"[97]","previouslyFormattedCitation":"[97]"},"properties":{"noteIndex":0},"schema":""}[97], copyright Elsevier. (c) Sketch of a Langevin-type transducer indirectly coupled reactor, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2004.10.004","ISSN":"13504177","abstract":"A novel concept was developed here for the continuous, contact- and contamination-free treatment of fluid mixtures with ultrasound. It is based on exciting a steel jacket with an ultrasonic transducer, which transmitted the sound waves via pressurised water to a glass tube installed inside the jacket. Thus, no metallic particles can be emitted into the sonicated fluid, which is a common problem when a sonotrode and a fluid are in direct contact. Moreover, contamination of the fluid from the environment can be avoided, making the novel ultrasonic flow-through cell highly suitable for aseptic production of pharmaceutical preparations. As a model system, vegetable oil-in-water emulsions, fed into the cell as coarse pre-emulsions, were studied. The mean droplet diameter was decreased by two orders of magnitude yielding Sauter diameters of 0.5 μm and below with good repeatability. Increasing the residence time in the ultrasonic field and the sonication power both decreased the emulsion mean diameter. Furthermore, the ultrasonic flow-through cell was found to be well suited for the production of nanoparticles of biodegradable polymers by the emulsion-solvent extraction/ evaporation method. Here, perfectly spherical particles of a volume mean diameter of less than 0.5 μm could be prepared. In conclusion, this novel technology offers a pharmaceutically interesting platform for nanodroplet and nanoparticle production and is well suited for aseptic continuous processing. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Freitas","given":"Sergio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hielscher","given":"Gerhard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merkle","given":"Hans P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gander","given":"Bruno","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2006"]]},"page":"76-85","title":"Continuous contact- and contamination-free ultrasonic emulsification - A useful tool for pharmaceutical development and production","type":"article-journal","volume":"13"},"uris":[""]}],"mendeley":{"formattedCitation":"[98]","plainTextFormattedCitation":"[98]","previouslyFormattedCitation":"[98]"},"properties":{"noteIndex":0},"schema":""}[98], copyright Elsevier. (d) Sketch of a Langevin-type transducer directly coupled reactor, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[34]","plainTextFormattedCitation":"[34]","previouslyFormattedCitation":"[34]"},"properties":{"noteIndex":0},"schema":""}[34] copyright Royal Society of Chemistry.3.1.2. Langevin-type transducer based reactorFor applications requiring relatively high ultrasonic powers, Langevin-type transducers are regarded as the most cost-effective choice, especially for low frequency ultrasound ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1109/TUFFC.2013.2675","abstract":"Power ultrasonic applications such as cutting, welding, and sonochemistry often use Langevin transducers to generate power ultrasound. Traditionally, it has been proposed that the piezoceramic stack of a Langevin transducer should be located in the nodal plane of the longitudinal mode of vibra- tion, ensuring that the piezoceramic elements are positioned under a uniform stress during transducer operation, maxi- mizing element efficiency and minimizing piezoceramic aging. However, this general design rule is often partially broken dur- ing the design phase if features such as a support flange or multiple piezoceramic stacks are incorporated into the trans- ducer architecture. Meanwhile, it has also been well document- ed in the literature that power ultrasonic devices driven at high excitation levels exhibit nonlinear behaviors similar to those observed in Duffing-type systems, such as resonant fre- quency shifts, the jump phenomenon, and hysteretic regions. This study investigates three Langevin transducers with differ- ent piezoceramic stack locations by characterizing their linear and nonlinear vibrational responses to understand how the stack location influences nonlinear behavior.","author":[{"dropping-particle":"","family":"Mathieson","given":"Andrew","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cardoni","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cerisola","given":"Niccolò","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lucas","given":"Margaret","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control","id":"ITEM-1","issue":"6","issued":{"date-parts":[["2013"]]},"page":"1126-1133","publisher":"IEEE","title":"The Influence of Piezoceramic Stack Location on Nonlinear Behavior of Langevin Transducers","type":"article-journal","volume":"60"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1109/TUFFC.2014.2932","ISSN":"08853010","abstract":"Applications involving high-power ultrasound are expanding rapidly as ultrasonic intensification opportunities are identified in new fields. This is facilitated through new technological developments and an evolution of current systems to tackle challenging problems. It is therefore important to continually update both the scientific and commercial communities on current system performance and limitations. To achieve this objective, this paper addresses two key aspects of high-power ultrasonic systems. In the first part, the review of high-power applications focuses on industrial applications and documents the developing technology from its early cleaning applications through to the advanced sonochemistry, cutting, and water treatment applications used today. The second part provides a comprehensive overview of measurement techniques used in conjunction with high-power ultrasonic systems. This is an important and evolving field which enables design and process engineers to optimize the behavior and/or operation of key metrics of system performance, such as field distribution or cavitation intensity. ? 1986-2012 IEEE.","author":[{"dropping-particle":"","family":"Harvey","given":"Gerald","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gachagan","given":"Anthony","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mutasa","given":"Tapiwa","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control","id":"ITEM-2","issue":"3","issued":{"date-parts":[["2014"]]},"page":"481-495","publisher":"IEEE","title":"Review of High-Power Ultrasound-Industrial Applications and Measurement Methods","type":"article-journal","volume":"61"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2016.08.009","ISSN":"18732828","abstract":"Cavitation generated using ultrasound can enhance the rates of several chemical reactions giving better selectivity based on the physical and chemical effects. The present review focuses on overview of the dif-ferent reactions that can be intensified using ultrasound followed by the discussion on the chemical kinetics for ultrasound assisted reactions, engineering aspects related to reactor designs and effect of operating parameters on the degree of intensification obtained for chemical synthesis. The cavitational effects in terms of magnitudes of collapse temperatures and collapse pressure, number of free radicals generated and extent of turbulence are strongly dependent on the operating parameters such as ultra-sonic power, frequency, duty cycle, temperature as well as physicochemical parameters of liquid medium which controls the inception of cavitation. Guidelines have been presented for the optimum selection based on the critical analysis of the existing literature so that maximum process intensification benefits can be obtained. Different reactor designs have also been analyzed with guidelines for efficient scale up of the sonochemical reactor, which would be dependent on the type of reaction, controlling mechanism of reaction, catalyst and activation energy requirements. Overall, it has been established that sonochemistry offers considerable potential for green and sustainable processing and efficient scale up procedures are required so as to harness the effects at actual commercial level.","author":[{"dropping-particle":"V.","family":"Sancheti","given":"Sonam","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2017"]]},"page":"527-543","publisher":"Elsevier B.V.","title":"A review of engineering aspects of intensification of chemical synthesis using ultrasound","type":"article-journal","volume":"36"},"uris":[""]}],"mendeley":{"formattedCitation":"[99–101]","plainTextFormattedCitation":"[99–101]","previouslyFormattedCitation":"[99–101]"},"properties":{"noteIndex":0},"schema":""}[99–101]. This transducer is made of piezoelectric ceramic rings clamped between a front and a back mass, which both serve to protect the delicate ceramic and prevent it from overheating by acting as a heat sink ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Mason","given":"Timothy J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lorimer","given":"John P.","non-dropping-particle":"","parse-names":false,"suffix":""}],"editor":[{"dropping-particle":"","family":"Anderson","given":"Bill","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issued":{"date-parts":[["2002"]]},"publisher":"Wiley","title":"Applied Sonochemistry: the uses of power ultrasound in chemistry and processing","type":"book"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultras.2008.06.007","ISSN":"0041624X","abstract":"Several approaches have been described for the manipulation of particles within an ultrasonic field. Of those based on standing waves, devices in which the critical dimension of the resonant chamber is less than a wavelength are particularly well suited to microfluidic, or \"lab on a chip\" applications. These might include pre-processing or fractionation of samples prior to analysis, formation of monolayers for cell interaction studies, or the enhancement of biosensor detection capability. The small size of microfluidic resonators typically places tight tolerances on the positioning of the acoustic node, and such systems are required to have high transduction efficiencies, for reasons of power availability and temperature stability. Further, the expense of many microfabrication methods precludes an iterative experimental approach to their development. Hence, the ability to design sub-wavelength resonators that are efficient, robust and have the appropriate acoustic energy distribution is extremely important. This paper discusses one-dimensional modelling used in the design of ultrasonic resonators for particle manipulation and gives example of their uses to predict and explain resonator behaviour. Particular difficulties in designing quarter wave systems are highlighted, and modelling is used to explain observed trends and predict performance of such resonators, including their performance with different coupling layer materials. ? 2008 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Hill","given":"Martyn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Townsend","given":"Rosemary J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Harris","given":"Nicholas R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics","id":"ITEM-2","issued":{"date-parts":[["2008"]]},"page":"521-528","publisher":"Elsevier B.V.","title":"Modelling for the robust design of layered resonators for ultrasonic particle manipulation","type":"article-journal","volume":"48"},"uris":[""]},{"id":"ITEM-3","itemData":{"author":[{"dropping-particle":"","family":"Lin","given":"Shuyu","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-3","issued":{"date-parts":[["2004"]]},"publisher":"Science Press, Beijing","title":"The mechanism and design of ultrasound transducer","type":"book"},"uris":[""]}],"mendeley":{"formattedCitation":"[59,96,102]","plainTextFormattedCitation":"[59,96,102]","previouslyFormattedCitation":"[59,96,102]"},"properties":{"noteIndex":0},"schema":""}[59,96,102]. As the front mass is usually made of a light metal and the back mass a heavy metal, the ultrasound wave is mainly irradiated from the front surface. Sometimes, a sonotrode is connected to the front surface, in order to guide the ultrasound to the working material ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.013","ISSN":"18732828","abstract":"Capillary reactors demonstrate outstanding potential for on-demand flow chemistry applications. However, non-uniform distribution of multiphase flows, poor solid handling, and the risk of clogging limit their usability for continuous manufacturing. While ultrasonic irradiation has been traditionally applied to address some of these limitations, their acoustic efficiency, uniformity and scalability to larger reactor systems are often disregarded. In this work, high-speed microscopic imaging reveals how cavitation-free ultrasound can unclog and prevent the blockage of capillary reactors. Modeling techniques are then adapted from traditional acoustic designs and applied to simulate and prototype sonoreactors with wider and more uniform sonication areas. Blade-, block- and cylindrical shape sonotrodes are optimized to accommodate longer capillary lengths in sonoreactors resonating at 28 kHz. Finally, a novel helicoidal capillary sonoreactor is proposed to potentially deal with a high concentration of solid particles in miniaturized flow chemistry. The acoustic designs and first principle rationalization presented here offer a transformative step forward in the scale-up of efficient capillary sonoreactors.","author":[{"dropping-particle":"","family":"Navarro-Brull","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"Andrew R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Giri","given":"Gaurav","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gómez","given":"Roberto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"105-113","publisher":"Elsevier","title":"Enabling low power acoustics for capillary sonoreactors","type":"article-journal","volume":"56"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1515/gps-2014-0052","abstract":"Possible drawbacks of microreactors are inefficient reactant mixing and the clogging of microchannels when solid-forming reactions are carried out or solid (catalysts) suspensions are used. Ultrasonic irradiation has been succesfully implemented for solving these problems in microreactor configurations ranging from capillaries immersed in ultrasonic baths to devices with miniaturized piezolelectric transducers. Moving forward in process intensification and sustainable development, the acoustic energy implementation requires a strategy to optimize the microreactor from an ultrasound viewpoint during its design. In this work, we present a simple analytical model that can be used as a guide to achieving a proper acoustic design of stacked microreactors. An example of this methodology was demonstrated through finite element analysis and it was compared with an experimental study found in the literature.","author":[{"dropping-particle":"","family":"Navarro-Brull","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Poveda","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ruiz-Femenia","given":"Rubén","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bonete","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ramis","given":"Jaime","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gómez","given":"Roberto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Green Processing and Synthesis","id":"ITEM-2","issued":{"date-parts":[["2014"]]},"page":"311-320","title":"Guidelines for the design of efficient sono-microreactors","type":"article-journal","volume":"3"},"uris":[""]}],"mendeley":{"formattedCitation":"[103,104]","plainTextFormattedCitation":"[103,104]","previouslyFormattedCitation":"[103,104]"},"properties":{"noteIndex":0},"schema":""}[103,104]. Langevin-type transducers typically dominate for applications where relatively large reactor volumes and thus high ultrasonic powers are required ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.122221","ISSN":"13858947","abstract":"? 2019 Elsevier B.V. This work is concerned with the effect of ultrasound on mixing and consequently on crystallization in millifluidic channels. An ultrasonic horn with frequency of 20 kHz was placed inside a vessel with a well-defined geometry containing a single capillary tube with internal diameter (I.D.) of 1.55 or 3.2 mm operated with a fluid flow rate between 1 and 17.6 ml/min. This system was employed to produce crystals of adipic acid in the range of 15–35 ?m. The effect of ultrasound on flow patterns, residence time distribution (RTD) and cooling crystallization were investigated experimentally and numerically. Simulations of acoustic and velocity fields inside the millichannel acting as crystallizer allowed characterizing the acoustic streaming generated within it. In the large capillary, especially at small flow rates, acoustic streaming influenced the flow field, inducing vortices and leading to significant changes in RTD. Conversely, in the small capillary, ultrasound affected the flow field and the RTD negligibly, and a laminar velocity profile with straight streamlines was obtained. As a consequence, different crystallization behaviours were observed in the two capillaries; in particular, while the mean crystal size increased with the sonication residence time in the 1.55 mm I.D. capillary, it decreased in the 3.2 mm I.D. capillary. This difference highlights the importance of considering acoustic streaming when designing sonocrystallizers.","author":[{"dropping-particle":"","family":"Valitov","given":"Gleb","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"122221","issued":{"date-parts":[["2020"]]},"page":"1-13","publisher":"Elsevier","title":"Effect of acoustic streaming on continuous flow sonocrystallization in millifluidic channels","type":"article-journal","volume":"379"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cep.2016.09.008","ISSN":"02552701","abstract":"A novel reactor was developed for ultrasound-assisted liquid–liquid extraction. This reactor design entails introducing short contact intervals for the microchannel tubing along the reactor plate channel to have a more focused transmission of the ultrasound. The non-contacted parts of the tubing are still under the influence of the ultrasound as a result of the pseudo-sonicated zone created by the adjacent intervals. The effect of introduction of these elements was first studied by comparing the thermal profiles with and without the presence of intervals and it was found that the maximum intensities along the channel become focused at these intervals. The influence of the intervals on a sonicated two-phase flow was also studied and revealed a repetitive splitting (at the intervals) and coalescence (downstream from the interval) of the emulsified aqueous phase. This dynamic change in the size of the emulsified aqueous phase introduces additional interfacial area and improves the mass transfer between the phases. The number of intervals was varied between three, five and seven. The five intervals showed the best performance. On comparing the five-interval design with a direct-contact design it was shown that the interval design gave the best improvement in yield for the process conditions studied.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-2","issued":{"date-parts":[["2017"]]},"page":"35-41","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid–liquid extraction with a novel interval-contact reactor","type":"article-journal","volume":"113"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/c2lc40595d","ISSN":"14730189","abstract":"Fragmentation of DNA is an essential step for many biological applications including the preparation of next-generation sequencing (NGS) libraries. As sequencing technologies push the limits towards single cell and single molecule resolution, it is of great interest to reduce the scale of this upstream fragmentation step. Here we describe a miniaturized DNA shearing device capable of processing sub-microliter samples based on acoustic shearing within a microfluidic chip. A strong acoustic field was generated by a Langevin-type piezo transducer and coupled into the microfluidic channel via the flexural lamb wave mode. Purified genomic DNA, as well as covalently cross-linked chromatin were sheared into various fragment sizes ranging from ～180 bp to 4 kb. With the use of standard PDMS soft lithography, our approach should facilitate the integration of additional microfluidic modules and ultimately allow miniaturized NGS workflows. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Tseng","given":"Qingzong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lomonosov","given":"Alexey M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Furlong","given":"Eileen E.M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merten","given":"Christoph A.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2012"]]},"page":"4677-4682","title":"Fragmentation of DNA in a sub-microliter microfluidic sonication device","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[105–107]","plainTextFormattedCitation":"[105–107]","previouslyFormattedCitation":"[105–107]"},"properties":{"noteIndex":0},"schema":""}[105–107].Based on the connection method between the transducer and microreactor, ultrasonic flow reactors can be divided into two categories, i.e., directly coupled and indirectly coupled. The former uses epoxy glue or a clamp to directly connect the transducer to the microreactor surface ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cep.2016.01.003","ISSN":"02552701","abstract":"A new method to apply ultrasound to a microchannel for liquid-liquid extraction was explored. The microchannel tubes are subjected to the ultrasound by direct contact with the transducer without the presence of a liquid medium. The design was constructed with the objectives of reproducibility, proper control of the ultrasound parameters and visibility of the behaviour of the two phase flow under the influence of ultrasound throughout the length of the channel. Two mechanisms of emulsion formation were observed. The effectiveness of the system under the influence of various operating and design parameters was quantified by calculating the yields of the two phase hydrolysis reaction of p-nitrophenyl acetate. The behaviour under various frequencies and amplitude was explored. At a frequency of 20.3. kHz, amplitude of 840. mV and flow rate of 0.1. ml/min the highest increase in yield was observed, which was almost 2.5 times that of the silent condition. A comparison was also made against silent batch and flow conditions to determine the actual effectiveness of the system. To obtain an identical yield of 75% the required residence time could be reduced by a factor of 20 in the sonicated flow condition compared to the silent batch condition.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"37-46","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid-liquid extraction in microchannels-A direct contact method","type":"article-journal","volume":"102"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/c2lc40595d","ISSN":"14730189","abstract":"Fragmentation of DNA is an essential step for many biological applications including the preparation of next-generation sequencing (NGS) libraries. As sequencing technologies push the limits towards single cell and single molecule resolution, it is of great interest to reduce the scale of this upstream fragmentation step. Here we describe a miniaturized DNA shearing device capable of processing sub-microliter samples based on acoustic shearing within a microfluidic chip. A strong acoustic field was generated by a Langevin-type piezo transducer and coupled into the microfluidic channel via the flexural lamb wave mode. Purified genomic DNA, as well as covalently cross-linked chromatin were sheared into various fragment sizes ranging from ～180 bp to 4 kb. With the use of standard PDMS soft lithography, our approach should facilitate the integration of additional microfluidic modules and ultimately allow miniaturized NGS workflows. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Tseng","given":"Qingzong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lomonosov","given":"Alexey M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Furlong","given":"Eileen E.M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merten","given":"Christoph A.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2012"]]},"page":"4677-4682","title":"Fragmentation of DNA in a sub-microliter microfluidic sonication device","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[34,107,108]","plainTextFormattedCitation":"[34,107,108]","previouslyFormattedCitation":"[34,107,108]"},"properties":{"noteIndex":0},"schema":""}[34,107,108], while the latter utilizes a transmission medium (usually liquid) to transport ultrasound from the transducer to the microreactor ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/b410015h","abstract":"Ultrasound was irradiated to a micro-1D and -2D space having a characteristic length of 200 mm, and the presence of cavitation was confirmed from video images, and the generation of OH radicals, which was quantitatively evaluated with fluorometry. Microspace","author":[{"dropping-particle":"","family":"Iida","given":"Yasuo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yasui","given":"Kyuichi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tuziuti","given":"Toru","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sivakumar","given":"Manickam","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Endo","given":"Yoshishige","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chem. Commun.","id":"ITEM-1","issued":{"date-parts":[["2004"]]},"page":"2280-2281","title":"Ultrasonic cavitation in microspace","type":"article-journal"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/cssc.201100369","ISBN":"1864-564X (Electronic)\\r1864-5631 (Linking)","ISSN":"1864564X","PMID":"22337650","abstract":"Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min(-1) range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.","author":[{"dropping-particle":"","family":"Hübner","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kressirer","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bludszuweit-Philipp","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lukow","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nich","given":"I.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schilling","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hieronymus","given":"H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liebner","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?hnisch","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"279-288","title":"Ultrasound and microstructures-a promising combination?","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-3","itemData":{"abstract":"A method for preventing plugging of a continuous-reaction channel-system caused by a by-product of a continuous-reaction being carried out in said channel-system comprises the step of generating at least one ultrasonic wave travelling through said channel-system by coupling in a flow direction of at least one process fluid of a plurality of process fluids said at least one ultrasonic wave into said at least one process fluid.","author":[{"dropping-particle":"","family":"Roberge","given":"Dominique","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Raimone","given":"Fabio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Quittmann","given":"Wilhelm","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gottsponer","given":"Michael","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Eyholzer","given":"Markus","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-3","issued":{"date-parts":[["2010"]]},"number":"WO2011023761","page":"1-17","publisher-place":"Switzerland","title":"Method for preventing plugging of a continuous-reaction channel-system and micro-reactor for carrying out the method.pdf","type":"patent"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1007/s10544-016-0097-4","ISSN":"15728781","abstract":"We demonstrate an acoustic platform for micro-vortexing in disposable polymer microfluidic chips with small-volume (20 μl) reaction chambers. The described method is demonstrated for a variety of standard vortexing functions, including mixing of fluids, re-suspension of a pellet of magnetic beads collected by a magnet placed on the chip, and lysis of cells for DNA extraction. The device is based on a modified Langevin-type ultrasonic transducer with an exponential horn for efficient coupling into the microfluidic chip, which is actuated by a low-cost fixed-frequency electronic driver board. The transducer is optimized by numerical modelling, and different demonstrated vortexing functions are realized by actuating the transducer for varying times; from fractions of a second for fluid mixing, to half a minute for cell lysis and DNA extraction. The platform can be operated during 1 min below physiological temperatures with the help of a PC fan, a Peltier element and an aluminum heat sink acting as the chip holder. As a proof of principle for sample preparation applications, we demonstrate on-chip cell lysis and DNA extraction within 25 s. The method is of interest for automating and chip-integrating sample preparation procedures in various biological assays.","author":[{"dropping-particle":"","family":"Iranmanesh","given":"Ida","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohlin","given":"Mathias","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ramachandraiah","given":"Harisha","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ye","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Russom","given":"Aman","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wiklund","given":"Martin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Biomedical Microdevices","id":"ITEM-4","issue":"71","issued":{"date-parts":[["2016"]]},"page":"1-7","publisher":"Biomedical Microdevices","title":"Acoustic micro-vortexing of fluids, particles and cells in disposable microfluidic chips","type":"article-journal","volume":"18"},"uris":[""]}],"mendeley":{"formattedCitation":"[68,109–111]","plainTextFormattedCitation":"[68,109–111]","previouslyFormattedCitation":"[68,109–111]"},"properties":{"noteIndex":0},"schema":""}[68,109–111]. The easiest way to construct an indirectly coupled reactor is by immersing a microreactor in a commercial ultrasound cleaning bath, under which several Langevin transducers are attached, see Figure 4b ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/op900306z","ISSN":"10836160","abstract":"Photodimerization of maleic anhydride (MA) gives insoluble precipitated products that can be a trigger to clog a conventional microreactor. To avoid this problem, we devised a microreactor that uses liquid/gas slug flow and ultrasonication. Inert N-2 gas introduced into the reaction solution swept through the reactor tube and transported precipitated products in the liquid segnients. Ultrasound vibrations inhibited the adhesion and sedimentation of precipitate in the reactor tube. The combination of gas and ultrasound prevented the tube from clogging. Fluorinated ethylene propylene (FEP) tubes of various sizes were investigated to use as a tube reactor. The tubes were wound around a high-pressure Hg lamp with a Pyrex immersion well which has been using generally as a light source of photoreaction, and the reaction solution was then passed through the tube and irradiated through the tube wall. The slug flow microreactor could be operated for more than 16 h continuously without clogging. Compared to using a batch reactor, this method achieves better product quality, improved conversion, and reduced waste.","author":[{"dropping-particle":"","family":"Horie","given":"Tomoaki","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sumino","given":"Motoshige","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tanaka","given":"Takumi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Matsushita","given":"Yoshihisa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ichimura","given":"Teijiro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yoshida","given":"Jun-Ichi","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-1","issued":{"date-parts":[["2010"]]},"page":"405-410","title":"Photodimerization of maleic anhydride in a microreactor without clogging","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c0sc00524j","ISSN":"20416520","abstract":"A continuous-flow palladium-catalyzed animation reaction was made possible through efficient handling of solids via acoustic irradiation. Various diarylamines were obtained with reaction times ranging from 20 s to 10 min. ? The Royal Society of Chemistry 2011.","author":[{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mcmullen","given":"Jonathan P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Science","id":"ITEM-2","issue":"2","issued":{"date-parts":[["2011"]]},"page":"287-290","title":"Palladium-catalyzed amination reactions in flow: Overcoming the challenges of clogging via acoustic irradiation","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.jiec.2009.09.008","ISSN":"1226086X","abstract":"A simple capillary microreactor was tested as a potential reactor to carry out a multiphase reaction. The hydrolysis of benzyl chloride in a biphasic system was investigated. The capillary microreactor was irradiated by 28 kHz ultrasound at different temperatures, capillary lengths and phase flow rates. It was found that the combination of microreactor technique and the ultrasound irradiation provides a promising protocol for process intensification. Under sonication conditions, higher conversions were obtained compared to silent conditions. The presence of ultrasound has affected the multiphase slug size and promoted better internal circulation within these slugs. Similar reactivities were noticed at higher temperature for both sonication and silent conditions. ? 2009 The Korean Society of Industrial and Engineering Chemistry.","author":[{"dropping-particle":"","family":"Aljbour","given":"Salah","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tagawa","given":"Tomohiko","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yamada","given":"Hiroshi","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Industrial and Engineering Chemistry","id":"ITEM-3","issued":{"date-parts":[["2009"]]},"page":"829-834","title":"Ultrasound-assisted capillary microreactor for aqueous-organic multiphase reactions","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.cep.2009.04.004","ISSN":"02552701","abstract":"In this work, the liquid-liquid catalytic phase transfer reaction between benzyl chloride with sodium sulfide was investigated in a capillary-microreactor assisted by ultrasound irradiation. A rational reaction mechanism was satisfactorily developed. The kinetics of the multiphase reaction was studied at different phase transfer catalyst concentration, sodium sulfide concentration and aqueous-to-organic phase flow rate ratio under both silent and sonication conditions. The reaction conversion was increased with an increase in the phase transfer catalyst concentration and sodium sulfide concentration under sonication conditions more profoundly than under silent conditions. Under sonication conditions, the reaction conversion was further enhanced by increasing the aqueous-to-organic phase flow rate ratio. However, under silent condition, such effect was negligible. In addition, the reaction system was studied in a mechanically stirred batch reactor under silent and sonication conditions. The reaction conversion was enhanced by increasing the agitation speed. The reaction conversion was further enhanced by the combination of mechanical agitation and ultrasound irradiation. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Aljbour","given":"Salah","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yamada","given":"Hiroshi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tagawa","given":"Tomohiko","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing","id":"ITEM-4","issued":{"date-parts":[["2009"]]},"page":"1167-1172","title":"Ultrasound-assisted phase transfer catalysis in a capillary microreactor","type":"article-journal","volume":"48"},"uris":[""]}],"mendeley":{"formattedCitation":"[97,112–114]","plainTextFormattedCitation":"[97,112–114]","previouslyFormattedCitation":"[97,112–114]"},"properties":{"noteIndex":0},"schema":""}[97,112–114]. The drawback of such a setup is that the water in the bath is also cavitating, which dissipates most of the input ultrasound energy and thus only a small portion of energy reaches the microreactor. To overcome this problem, Hübner et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/cssc.201100369","ISBN":"1864-564X (Electronic)\\r1864-5631 (Linking)","ISSN":"1864564X","PMID":"22337650","abstract":"Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min(-1) range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.","author":[{"dropping-particle":"","family":"Hübner","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kressirer","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bludszuweit-Philipp","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lukow","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nich","given":"I.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schilling","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hieronymus","given":"H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liebner","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?hnisch","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"279-288","title":"Ultrasound and microstructures-a promising combination?","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[109]","plainTextFormattedCitation":"[109]","previouslyFormattedCitation":"[109]"},"properties":{"noteIndex":0},"schema":""}[109] positioned the microreactor above the transducer in a stainless steel vessel filled with pressurized water (at about 4.5 bar), which acts simultaneously as heat and ultrasound transfer medium. Similarly, Freitas et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2004.10.004","ISSN":"13504177","abstract":"A novel concept was developed here for the continuous, contact- and contamination-free treatment of fluid mixtures with ultrasound. It is based on exciting a steel jacket with an ultrasonic transducer, which transmitted the sound waves via pressurised water to a glass tube installed inside the jacket. Thus, no metallic particles can be emitted into the sonicated fluid, which is a common problem when a sonotrode and a fluid are in direct contact. Moreover, contamination of the fluid from the environment can be avoided, making the novel ultrasonic flow-through cell highly suitable for aseptic production of pharmaceutical preparations. As a model system, vegetable oil-in-water emulsions, fed into the cell as coarse pre-emulsions, were studied. The mean droplet diameter was decreased by two orders of magnitude yielding Sauter diameters of 0.5 μm and below with good repeatability. Increasing the residence time in the ultrasonic field and the sonication power both decreased the emulsion mean diameter. Furthermore, the ultrasonic flow-through cell was found to be well suited for the production of nanoparticles of biodegradable polymers by the emulsion-solvent extraction/ evaporation method. Here, perfectly spherical particles of a volume mean diameter of less than 0.5 μm could be prepared. In conclusion, this novel technology offers a pharmaceutically interesting platform for nanodroplet and nanoparticle production and is well suited for aseptic continuous processing. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Freitas","given":"Sergio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hielscher","given":"Gerhard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merkle","given":"Hans P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gander","given":"Bruno","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2006"]]},"page":"76-85","title":"Continuous contact- and contamination-free ultrasonic emulsification - A useful tool for pharmaceutical development and production","type":"article-journal","volume":"13"},"uris":[""]}],"mendeley":{"formattedCitation":"[98]","plainTextFormattedCitation":"[98]","previouslyFormattedCitation":"[98]"},"properties":{"noteIndex":0},"schema":""}[98] developed an ultrasonic flow-through cell consisting of a cylindrical steel jacket, in which a glass tube of 2 mm inner diameter for conveying the fluids was installed, see Figure 4c. A sonotrode fixed to a Langevin-type transducer was welded to the outside of the steel jacket to provide ultrasonic vibration. Through the space between the glass tube and the jacket, pressurized water (between 4.5 and 5.5 bar) was passed for sound conduction and temperature control. These indirect coupling methods have advantages of modularity and good temperature control ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/cssc.201100369","ISBN":"1864-564X (Electronic)\\r1864-5631 (Linking)","ISSN":"1864564X","PMID":"22337650","abstract":"Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min(-1) range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.","author":[{"dropping-particle":"","family":"Hübner","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kressirer","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bludszuweit-Philipp","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lukow","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nich","given":"I.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schilling","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hieronymus","given":"H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liebner","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?hnisch","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"279-288","title":"Ultrasound and microstructures-a promising combination?","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[109]","plainTextFormattedCitation":"[109]","previouslyFormattedCitation":"[109]"},"properties":{"noteIndex":0},"schema":""}[109], but also disadvantages of low energy transmission efficiency due to the attenuation in the transmission medium and reflection at the two liquid/solid interfaces ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/cssc.201100369","ISBN":"1864-564X (Electronic)\\r1864-5631 (Linking)","ISSN":"1864564X","PMID":"22337650","abstract":"Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min(-1) range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.","author":[{"dropping-particle":"","family":"Hübner","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kressirer","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bludszuweit-Philipp","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lukow","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nich","given":"I.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schilling","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hieronymus","given":"H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liebner","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?hnisch","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"279-288","title":"Ultrasound and microstructures-a promising combination?","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[109]","plainTextFormattedCitation":"[109]","previouslyFormattedCitation":"[109]"},"properties":{"noteIndex":0},"schema":""}[109].Direct coupling is a more efficient way to transport ultrasound energy. Tseng et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c2lc40595d","ISSN":"14730189","abstract":"Fragmentation of DNA is an essential step for many biological applications including the preparation of next-generation sequencing (NGS) libraries. As sequencing technologies push the limits towards single cell and single molecule resolution, it is of great interest to reduce the scale of this upstream fragmentation step. Here we describe a miniaturized DNA shearing device capable of processing sub-microliter samples based on acoustic shearing within a microfluidic chip. A strong acoustic field was generated by a Langevin-type piezo transducer and coupled into the microfluidic channel via the flexural lamb wave mode. Purified genomic DNA, as well as covalently cross-linked chromatin were sheared into various fragment sizes ranging from ～180 bp to 4 kb. With the use of standard PDMS soft lithography, our approach should facilitate the integration of additional microfluidic modules and ultimately allow miniaturized NGS workflows. ? 2012 The Royal Society of Chemistry.","author":[{"dropping-particle":"","family":"Tseng","given":"Qingzong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lomonosov","given":"Alexey M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Furlong","given":"Eileen E.M.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merten","given":"Christoph A.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"4677-4682","title":"Fragmentation of DNA in a sub-microliter microfluidic sonication device","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[107]","plainTextFormattedCitation":"[107]","previouslyFormattedCitation":"[107]"},"properties":{"noteIndex":0},"schema":""}[107] directly bonded a glass plate microfluidic chip to the front face of a Langevin transducer with epoxy glue. A strong acoustic field was transferred into the microfluidic channel via the flexural lamb wave vibration of the glass plate, which is highly sensitive to the thickness, density, elastic properties and structure of the microreactor. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[34]","plainTextFormattedCitation":"[34]","previouslyFormattedCitation":"[34]"},"properties":{"noteIndex":0},"schema":""}[34] matched the structure of a Langevin transducer and a microreactor plate to form a half wavelength resonator in the longitudinal direction, where the antinode plane with highest sound intensity is located at the microreactor, see Figure 4d. This novel design not only generates a uniform and strong acoustic field density, but also maximizes the energy efficiency and lifespan of the transducer. Despite these advantages, direct coupling reduces flexibility and introduces difficulties regarding temperature control. As the transducers and microreactors are usually rigidly glued together, disconnecting and replacing them is normally not easy. Moreover, the heat generated by the ultrasonic transducer is directly transported into the microreactor, and in case of high input power, air cooling is even not sufficient to remove the large amount of heat ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cej.2019.05.157","ISSN":"13858947","abstract":"Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qiang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-2","issue":"April","issued":{"date-parts":[["2019"]]},"page":"68-78","publisher":"Elsevier","title":"Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature","type":"article-journal","volume":"374"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-3","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[34,67,115]","plainTextFormattedCitation":"[34,67,115]","previouslyFormattedCitation":"[34,67,115]"},"properties":{"noteIndex":0},"schema":""}[34,67,115]. One method to alleviate such temperature rise is to apply pulsed ultrasound, in order to reduce the power consumption. In some cases, it has been reported that applying ultrasound in a pulsed mode does not reduce the acoustic effect compared to continuous mode ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1143/JJAP.47.4111","author":[{"dropping-particle":"","family":"Choi","given":"Pak-kon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kaneko","given":"Yoshihisa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Meguro","given":"Taichi","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Japanese Journal of Applied Physics","id":"ITEM-1","issue":"5","issued":{"date-parts":[["2008"]]},"page":"4111-4114","title":"Enhancement of Sonoluminescence and Bubble Dynamics using Pulsed Ultrasound at 103 kHz","type":"article-journal","volume":"47"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/0301-5629(81)90005-3","abstract":"Iodine-131 labeled sodium iodide was used to demonstrate an iodine release reaction indicative of cavitation activity. Exposure of Na~3q at varying pulsed regimes (1:1 duty cycle, 60 sec-60/zsec pulse duration) and intensities (10--30W/cm 2) resulted in an increased efficiency of pulsed ultrasound to produce iodine release compared to continuous wave exposures. A model based on the concurrent operation of two mechanisms has been proposed to explain this phenomenon.","author":[{"dropping-particle":"","family":"Ciaravino","given":"Victor","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Flynn","given":"H G","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Miller","given":"Morton W.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasound in Medicine and Biology","id":"ITEM-2","issued":{"date-parts":[["1981"]]},"page":"159-166","title":"Pulsed enhancement of acoustic cavitation: a postulated model","type":"article-journal","volume":"7"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.cep.2017.01.001","ISSN":"02552701","abstract":"This work studies the use of pulsed ultrasound during cooling crystallization of paracetamol. The effect of the pulse time on the nucleation temperature, crystal size and shape was evaluated and compared to silent conditions and continuous sonication. Most work is performed in a batch crystallizer, though some preliminary data in a recirculation configuration is also provided. In both setups, the nucleation temperature increased by at least 8 °C when ultrasound was applied compared to the non-sonicated case. When ultrasound is switched on more than 10% of the time, a similar nucleation temperature as with continuous treatment is obtained. At this minimal pulse setting, a bubble population, consisting of both oscillating and dissolving bubbles, is present in the vessel at all times. The pulse threshold can be validated using bubble dissolution calculations, and its existence leads to a vast reduction in ultrasonic energy consumption compared to continuous sonication. Finally, this work shows that the final particle size of paracetamol can be controlled in the batch setup by the pulse conditions, without affecting the crystal shape. The recirculation system shows a similar response, although further validation is recommended.","author":[{"dropping-particle":"","family":"Gielen","given":"Bjorn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kusters","given":"Piet","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Thomassen","given":"Leen C.J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing - Process Intensification","id":"ITEM-3","issued":{"date-parts":[["2017"]]},"page":"55-66","publisher":"Elsevier B.V.","title":"Energy efficient crystallization of paracetamol using pulsed ultrasound","type":"article-journal","volume":"114"},"uris":[""]}],"mendeley":{"formattedCitation":"[116–118]","plainTextFormattedCitation":"[116–118]","previouslyFormattedCitation":"[116–118]"},"properties":{"noteIndex":0},"schema":""}[116–118]. Delacour et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]}],"mendeley":{"formattedCitation":"[45]","plainTextFormattedCitation":"[45]","previouslyFormattedCitation":"[45]"},"properties":{"noteIndex":0},"schema":""}[45] reported that applying ultrasound for 12.5% of the residence time was sufficient to prevent microchannel clogging for the synthesis of barium sulfate particles, while decreasing the temperature rise of the reactor from 7 °C to less than 1 °C after 5 reactor volumes. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[93]","plainTextFormattedCitation":"[93]","previouslyFormattedCitation":"[93]"},"properties":{"noteIndex":0},"schema":""}[93] found that applying ultrasound 37.5% per residence time produces a particle size distribution as narrow as that of continuous ultrasound for the synthesis of calcium carbonate particles. Another method to solve the temperature control issue is by combining direct and indirect coupling. John et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115] developed a hybrid contact reactor consisting of a Langevin transducer bolted to a mini-bath, in which PFA tubing was inserted, which was in contact with the transducer at several separate intervals, see Figure 7c. The intervals directly transported ultrasound from the transducer to the tubing, while the cooling water in the bath was used to both transmit ultrasound and control the temperature in the reactor. This hybrid system performed better than the indirectly coupled reactor (20%– to 27% increase in yield) for a liquid–-liquid extraction process.Most of the ultrasonic flow reactors reported in literature can be classified into one of the above described reactor categories. The different designs applied in practice are described in the following section. It was found that piezoelectric plate reactors are mostly used at a laboratory scale because of their versatility and ease of fabrication. While Langevin-type reactors are more applied for both large and small scale applications, due to higher ultrasound energy transmission efficiencies and a wider operating range in terms of power. Remarkably, ultrasonic bath reactors are commonly used in organic synthesis, which is mostly due to their availability, operability and flexibility.3.2. Reactor characterizationUnderstanding how the mechanisms behind low and high frequency ultrasound applied to confined channels is important for the design of ultrasonic micro- and milli-reactors ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]}],"mendeley":{"formattedCitation":"[119]","plainTextFormattedCitation":"[119]","previouslyFormattedCitation":"[119]"},"properties":{"noteIndex":0},"schema":""}[119]. For this reason, different characterization methods have been developed, which have mostly been applied to batch reactors. Table 1 aims to summarize the characterization methods. The objectives and equipment needed for those measurements are also described.Table 1. Summary of major characterization methods and the corresponding objectives and procedures.MethodType of methodObjectivesMaterialsReferenceSonochemiluminescence of luminolExperimental,Chemical,QualitativeObservation of cavitation activity distributionAqueous solution of luminol and sodium hydroxide.ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-3","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[76,120,121]","plainTextFormattedCitation":"[76,120,121]","previouslyFormattedCitation":"[76,120,121]"},"properties":{"noteIndex":0},"schema":""}[76,120,121]Dosimetries: salicylic acid, Fricke, Weissler, terephtalicterephthalic acidExperimental,Chemical,QuantitativeGeneral cavitation activity measurement, cavitation yieldAnalysis method: spectrophotometry, HPLC analysis.ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/S1350-4177(03)00084-1","ISBN":"1350-4177","ISSN":"13504177","PMID":"12726951","abstract":"Fricke reaction, KI oxidation and decomposition of porphyrin derivatives by use of seven types of sonochemical apparatus in four different laboratories were examined in the range of frequency of 19.5 kHz to 1.2 MHz. The ultrasonic energy dissipated into an apparatus was determined also by calorimetry. Sonochemical efficiency of Fricke reaction and KI oxidation was defined as the number of reacted molecule per unit ultrasonic energy. The sonochemical efficiency is independent of experimental conditions such as the shape of sample cell and irradiation instruments, but depends on the ultrasonic frequency. We propose the KI oxidation dosimetry using 0.1 moldm-3KI solution as a standard method to calibrate the sonochemical efficiency of an individual reaction system. ? 2002 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Koda","given":"Shinobu","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kimura","given":"Takahide","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kondo","given":"Takashi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mitome","given":"Hideto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2003"]]},"note":"the aim of this paper is to establish a standard method to calibrate sonochemical efficiency. \nMeasurement of the calorimetric power: calorimetry is calculated from the temperature rise per sonication time at the time zero. \nDefinition of the sonochemical efficiency (ES-value) corresponds to the concentration of the compounds divided by the ultrasonic energy density (mol dm-3)/(J dm-3)","page":"149-156","title":"A standard method to calibrate sonochemical efficiency of an individual reaction system","type":"article-journal","volume":"10"},"uris":[""]}],"mendeley":{"formattedCitation":"[119,121,122]","plainTextFormattedCitation":"[119,121,122]","previouslyFormattedCitation":"[119,121,122]"},"properties":{"noteIndex":0},"schema":""}[119,121,122]Hydrophone measurementExperimental,Physical,QuantitativeAcoustic pressure mapping. Observation of standing waves.Hydrophone probe, oscilloscope.ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-3","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]}],"mendeley":{"formattedCitation":"[76,119,121]","plainTextFormattedCitation":"[76,119,121]","previouslyFormattedCitation":"[76,119,121]"},"properties":{"noteIndex":0},"schema":""}[76,119,121]Temperature mappingExperimental,Physical,QualitativeTemperature mapping to observe hot spots.Thermal camera.ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.09.008","ISSN":"02552701","abstract":"A novel reactor was developed for ultrasound-assisted liquid–liquid extraction. This reactor design entails introducing short contact intervals for the microchannel tubing along the reactor plate channel to have a more focused transmission of the ultrasound. The non-contacted parts of the tubing are still under the influence of the ultrasound as a result of the pseudo-sonicated zone created by the adjacent intervals. The effect of introduction of these elements was first studied by comparing the thermal profiles with and without the presence of intervals and it was found that the maximum intensities along the channel become focused at these intervals. The influence of the intervals on a sonicated two-phase flow was also studied and revealed a repetitive splitting (at the intervals) and coalescence (downstream from the interval) of the emulsified aqueous phase. This dynamic change in the size of the emulsified aqueous phase introduces additional interfacial area and improves the mass transfer between the phases. The number of intervals was varied between three, five and seven. The five intervals showed the best performance. On comparing the five-interval design with a direct-contact design it was shown that the interval design gave the best improvement in yield for the process conditions studied.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"35-41","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid–liquid extraction with a novel interval-contact reactor","type":"article-journal","volume":"113"},"uris":[""]}],"mendeley":{"formattedCitation":"[106]","plainTextFormattedCitation":"[106]","previouslyFormattedCitation":"[106]"},"properties":{"noteIndex":0},"schema":""}[106]Calorimetric measurementExperimental,Physical,QuantitativeTemperature rise measurements. Estimation of power density.Temperature probe.ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/B978-0-12-801530-8.00005-0","ISBN":"9780128015308","author":[{"dropping-particle":"","family":"Asakura","given":"Yoshiyuki","non-dropping-particle":"","parse-names":false,"suffix":""}],"chapter-number":"Chapter 15","container-title":"Sonochemistry and the Acoustic Bubble","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"119-150","publisher":"Elsevier Inc.","title":"Experimental Methods in Sonochemistry","type":"chapter"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/S1350-4177(03)00084-1","ISBN":"1350-4177","ISSN":"13504177","PMID":"12726951","abstract":"Fricke reaction, KI oxidation and decomposition of porphyrin derivatives by use of seven types of sonochemical apparatus in four different laboratories were examined in the range of frequency of 19.5 kHz to 1.2 MHz. The ultrasonic energy dissipated into an apparatus was determined also by calorimetry. Sonochemical efficiency of Fricke reaction and KI oxidation was defined as the number of reacted molecule per unit ultrasonic energy. The sonochemical efficiency is independent of experimental conditions such as the shape of sample cell and irradiation instruments, but depends on the ultrasonic frequency. We propose the KI oxidation dosimetry using 0.1 moldm-3KI solution as a standard method to calibrate the sonochemical efficiency of an individual reaction system. ? 2002 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Koda","given":"Shinobu","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kimura","given":"Takahide","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kondo","given":"Takashi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mitome","given":"Hideto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2003"]]},"note":"the aim of this paper is to establish a standard method to calibrate sonochemical efficiency. \nMeasurement of the calorimetric power: calorimetry is calculated from the temperature rise per sonication time at the time zero. \nDefinition of the sonochemical efficiency (ES-value) corresponds to the concentration of the compounds divided by the ultrasonic energy density (mol dm-3)/(J dm-3)","page":"149-156","title":"A standard method to calibrate sonochemical efficiency of an individual reaction system","type":"article-journal","volume":"10"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.cej.2010.11.069","ISBN":"1385-8947","ISSN":"13858947","abstract":"The spectacular effects observed during acoustic cavitation phenomena have been successfully employed for a number of applications on laboratory scale of operation but a well defined design and scale up methodology is lacking. The present work aims at developing a unified approach for the selection of different operating and geometric parameters for large scale sonochemical reactors with a special emphasis on heterogeneous systems. In the case of heterogeneous systems, apart from optimum selection of operating and geometric parameters, it is also important to understand the mixing and hydrodynamic characteristics due to the presence of solid/gas phases in the liquid medium. Also the quantification of attenuation of the incident sound energy has been discussed, which can be important design consideration in heterogeneous systems. Recommendations have been made for optimum selection of frequency of irradiation and power dissipation rate/irradiation intensity as well as the liquid phase physicochemical properties for the given physicochemical transformation. The discussion also highlights' the recent advances in development of sonochemical reactors focusing on reactor geometry and location of transducers in batch and continuous scale of operation. ? 2010 Elsevier B.V.","author":[{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pandit","given":"Aniruddha B.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-3","issued":{"date-parts":[["2011"]]},"page":"1066-1082","publisher":"Elsevier B.V.","title":"Sonochemical reactors: Important design and scale up considerations with a special emphasis on heterogeneous systems","type":"article-journal","volume":"166"},"uris":[""]}],"mendeley":{"formattedCitation":"[30,122,123]","plainTextFormattedCitation":"[30,122,123]","previouslyFormattedCitation":"[30,122,123]"},"properties":{"noteIndex":0},"schema":""}[30,122,123]Impedance measurementExperimental,Physical,QuantitativeResonance conditions: resonance and anti-resonance frequency.Impedance analyzerADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2015.01.017","ISBN":"1873-2828 (Electronic)\\r1350-4177 (Linking)","ISSN":"18732828","PMID":"25640681","abstract":"The influence of ultrasonic frequency and intensity on particle shape, tap density and particle size distribution was investigated during the precipitation of manganese carbonate. For the first time, a broad frequency range of 94 till 1135 kHz was studied in one single reactor setup. Smaller and more spherical particles were observed during sonication compared to silent conditions. Lower frequencies and increased intensities result in smaller and more spherical particles. The most spherical particles with superior tap densities are obtained at the lowest frequency and most elevated intensity. Moreover, the results indicate that a particle size threshold exists, below which the particle size cannot be reduced by a further increase of the ultrasonic intensity or reduction of the frequency. Sonication of already formed spherical powders resulted in particles with smaller sizes but unaffected shapes. Finally, one test with pulsed ultrasonic irradiation resulted in equally sized particles with similar sphericity as the ones produced under continuous sonication.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coker","given":"Nico","non-dropping-particle":"De","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gielen","given":"Bjorn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"note":"Influence fo ultrasonic frequency and intensity.","page":"64-72","publisher":"Elsevier B.V.","title":"Ultrasound precipitation of manganese carbonate: The effect of power and frequency on particle properties","type":"article-journal","volume":"26"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[34,45,124]","plainTextFormattedCitation":"[34,45,124]","previouslyFormattedCitation":"[34,45,124]"},"properties":{"noteIndex":0},"schema":""}[34,45,124]Pressure acoustic mappingNumerical,QuantitativeHelmholtz equationNumerical simulation softwareADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2013.03.012","ISSN":"13504177","abstract":"This paper presents a three-dimensional numercial simulation of sonochemical degradation upon cavitational activity. The model relates the simulation of the acoustic pressure distribution to the sonochemical reaction rate. As a case study, the thermal degradation of carbon tetrachloride during sonication is studied in a tubular milliscale reactor. The model is used to optimize the reactor diameter, ultrasound frequency and power dissipated to the ultrasound transducers. The results indicate that multiple transducers at a moderate power level are more efficient than one transducer with high power level. Furthermore, the average cavity volume fraction is proposed as a reaction independent parameter to estimate the optimal reactor design. Within the results obtained in this paper, it appears possible to optimise reactor design based on this parameter. ? 2013 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Honings","given":"Aurélie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Degrève","given":"Jan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Van","family":"Gerven","given":"Tom","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2013"]]},"page":"1345-1352","publisher":"Elsevier B.V.","title":"Investigation of design parameters in ultrasound reactors with confined channels","type":"article-journal","volume":"20"},"uris":[""]}],"mendeley":{"formattedCitation":"[119,120,125]","plainTextFormattedCitation":"[119,120,125]","previouslyFormattedCitation":"[119,120,125]"},"properties":{"noteIndex":0},"schema":""}[119,120,125]Simulation of primary and secondary effectNumerical,QuantitativeTemperature, bubble yieldNumerical simulation softwareADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2013.03.012","ISSN":"13504177","abstract":"This paper presents a three-dimensional numercial simulation of sonochemical degradation upon cavitational activity. The model relates the simulation of the acoustic pressure distribution to the sonochemical reaction rate. As a case study, the thermal degradation of carbon tetrachloride during sonication is studied in a tubular milliscale reactor. The model is used to optimize the reactor diameter, ultrasound frequency and power dissipated to the ultrasound transducers. The results indicate that multiple transducers at a moderate power level are more efficient than one transducer with high power level. Furthermore, the average cavity volume fraction is proposed as a reaction independent parameter to estimate the optimal reactor design. Within the results obtained in this paper, it appears possible to optimise reactor design based on this parameter. ? 2013 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Honings","given":"Aurélie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Degrève","given":"Jan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Van","family":"Gerven","given":"Tom","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2013"]]},"page":"1345-1352","publisher":"Elsevier B.V.","title":"Investigation of design parameters in ultrasound reactors with confined channels","type":"article-journal","volume":"20"},"uris":[""]}],"mendeley":{"formattedCitation":"[119,125]","plainTextFormattedCitation":"[119,125]","previouslyFormattedCitation":"[119,125]"},"properties":{"noteIndex":0},"schema":""}[119,125]When working with ultrasonic devices, it is necessary to determine the resonance condition of the system. This information can be provided by impedance analyses ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc01431f","ISBN":"1473-0189","ISSN":"14730189","PMID":"25537767","abstract":"The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type trans- ducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to inten- sify gas–liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3–5.7 times.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Xiaoli","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xu","given":"Jie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"1145-1152","publisher":"The Royal Society of Chemistry","title":"A high-power ultrasonic microreactor and its application in gas–liquid mass transfer intensification","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2015.01.017","ISBN":"1873-2828 (Electronic)\\r1350-4177 (Linking)","ISSN":"18732828","PMID":"25640681","abstract":"The influence of ultrasonic frequency and intensity on particle shape, tap density and particle size distribution was investigated during the precipitation of manganese carbonate. For the first time, a broad frequency range of 94 till 1135 kHz was studied in one single reactor setup. Smaller and more spherical particles were observed during sonication compared to silent conditions. Lower frequencies and increased intensities result in smaller and more spherical particles. The most spherical particles with superior tap densities are obtained at the lowest frequency and most elevated intensity. Moreover, the results indicate that a particle size threshold exists, below which the particle size cannot be reduced by a further increase of the ultrasonic intensity or reduction of the frequency. Sonication of already formed spherical powders resulted in particles with smaller sizes but unaffected shapes. Finally, one test with pulsed ultrasonic irradiation resulted in equally sized particles with similar sphericity as the ones produced under continuous sonication.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Coker","given":"Nico","non-dropping-particle":"De","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gielen","given":"Bjorn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2015"]]},"note":"Influence fo ultrasonic frequency and intensity.","page":"64-72","publisher":"Elsevier B.V.","title":"Ultrasound precipitation of manganese carbonate: The effect of power and frequency on particle properties","type":"article-journal","volume":"26"},"uris":[""]}],"mendeley":{"formattedCitation":"[34,45,124]","plainTextFormattedCitation":"[34,45,124]","previouslyFormattedCitation":"[34,45,124]"},"properties":{"noteIndex":0},"schema":""}[34,45,124], where the reactor impedance is measured as a function of actuation frequency, which indicates the anti-resonance and resonance frequencies of the reactor, mentioned in section 3.1.Low frequency ultrasound is associated with the collapse of cavitation bubbles, which results in a local increase of pressure and temperature. These primary effects can then also induce secondary effects, e.g., the formation of radicals. The characterization methods applicable to low frequency ultrasound aim to qualitatively or quantitatively measure these primary and secondary effects.Hydrophones are able to quantitatively measure the acoustic pressure field distribution in a reactor cavity, which allows us to locate the nodes and antinodes of an acoustic wave, i.e., the most active parts, in terms of cavitation activity ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c002363a","ISSN":"14730189","abstract":"We present a study on achieving intense acoustic cavitation generated by ultrasonic vibrations in polydimethylsiloxane (PDMS) based microfluidic devices. The substrate to which the PDMS is bonded was forced into oscillation with a simple piezoelectric transducer attached at 5 mm from the device to a microscopic glass slide. The transducer was operated at 100 kHz with driving voltages ranging between 20 V and 230 V. Close to the glass surface, pressure and vibration amplitudes of up to 20 bar and 400 nm were measured respectively. It is found that this strong forcing leads to the excitation of nonlinear surface waves when gas-liquid interfaces are present in the microfluidic channels. Also, it is observed that nuclei leading to intense inertial cavitation are generated by the entrapment of gas pockets at those interfaces. Subsequently, cavitation bubble clusters with void fractions of more than 50% are recorded with high-speed photography at up to 250000 frames/s. The cavitation clusters can be sustained through the continuous injection of gas using a T-junction in the microfluidic device. ? The Royal Society of Chemistry 2010.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Siew-Wan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"Dave Siak-Wei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"Evert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wong","given":"Victor V.T.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Camattari","given":"Andrea","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Claus-Dieter","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2010"]]},"page":"1848-1855","title":"Creation of cavitation activity in a microfluidic device through acoustically driven capillary waves","type":"article-journal","volume":"10"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-2","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]}],"mendeley":{"formattedCitation":"[76,77]","plainTextFormattedCitation":"[76,77]","previouslyFormattedCitation":"[76,77]"},"properties":{"noteIndex":0},"schema":""}[76,77]. This method was used by Verhaagen et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[121]","plainTextFormattedCitation":"[121]","previouslyFormattedCitation":"[121]"},"properties":{"noteIndex":0},"schema":""}[121] to determine the position in an ultrasonic bath where their cCavitation iIntensification bBag (CIB) would be most effective, see Figure 7a. However, hydrophone measurements show some drawbacks, for instance it is not possible to directly obtain the acoustic pressure field in the reactor channel as the hydrophone probe diameter is usually larger than the channel diameter. And Tthe hydrophone probe could also disturb cavitation activity patterns, as it can act as a nucleation site for cavitation bubbles.A second approach to obtain a qualitative distribution of the acoustic pressure field is through sonochemiluminescence. As mentioned earlier in section 2.1, the collapse of cavitation bubbles leads to the formation of radicals, such as HO. and H., which can then react with chemicals. This method is based on the reaction between 3-aminophtalhydrazide, also called luminol, with HO. radicals to emit luminescence light. With this method a visual representation of the cavitation zones in a reactor can be obtained by using a camera with long term exposure ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-3","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-4","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]}],"mendeley":{"formattedCitation":"[76,119–121]","plainTextFormattedCitation":"[76,119–121]","previouslyFormattedCitation":"[76,119–121]"},"properties":{"noteIndex":0},"schema":""}[76,119–121]. Using this method, Tandiono et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]}],"mendeley":{"formattedCitation":"[76]","plainTextFormattedCitation":"[76]","previouslyFormattedCitation":"[76]"},"properties":{"noteIndex":0},"schema":""}[76] found that cavitation effects is more profound near a gas–-liquid interface. This led to the introduction of a gaseous phase for a range of applications to improve cavitation phenomena, discussed in section 4.The cavitation activity in a reactor can also be quantified using chemical dosimetries. The most used chemical dosimetry is the Weissler reaction. This method is based on the degradation of potassium iodide into triiodure ions (I3-), due to the reaction with the radicals produced by ultrasound, which can be then quantified by ultraviolet spectrophotometry ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/B978-0-12-801530-8.00005-0","ISBN":"9780128015308","author":[{"dropping-particle":"","family":"Asakura","given":"Yoshiyuki","non-dropping-particle":"","parse-names":false,"suffix":""}],"chapter-number":"Chapter 15","container-title":"Sonochemistry and the Acoustic Bubble","id":"ITEM-3","issued":{"date-parts":[["2015"]]},"page":"119-150","publisher":"Elsevier Inc.","title":"Experimental Methods in Sonochemistry","type":"chapter"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/S1350-4177(03)00084-1","ISBN":"1350-4177","ISSN":"13504177","PMID":"12726951","abstract":"Fricke reaction, KI oxidation and decomposition of porphyrin derivatives by use of seven types of sonochemical apparatus in four different laboratories were examined in the range of frequency of 19.5 kHz to 1.2 MHz. The ultrasonic energy dissipated into an apparatus was determined also by calorimetry. Sonochemical efficiency of Fricke reaction and KI oxidation was defined as the number of reacted molecule per unit ultrasonic energy. The sonochemical efficiency is independent of experimental conditions such as the shape of sample cell and irradiation instruments, but depends on the ultrasonic frequency. We propose the KI oxidation dosimetry using 0.1 moldm-3KI solution as a standard method to calibrate the sonochemical efficiency of an individual reaction system. ? 2002 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Koda","given":"Shinobu","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kimura","given":"Takahide","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kondo","given":"Takashi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mitome","given":"Hideto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2003"]]},"note":"the aim of this paper is to establish a standard method to calibrate sonochemical efficiency. \nMeasurement of the calorimetric power: calorimetry is calculated from the temperature rise per sonication time at the time zero. \nDefinition of the sonochemical efficiency (ES-value) corresponds to the concentration of the compounds divided by the ultrasonic energy density (mol dm-3)/(J dm-3)","page":"149-156","title":"A standard method to calibrate sonochemical efficiency of an individual reaction system","type":"article-journal","volume":"10"},"uris":[""]}],"mendeley":{"formattedCitation":"[119,121–123]","plainTextFormattedCitation":"[119,121–123]","previouslyFormattedCitation":"[119,121–123]"},"properties":{"noteIndex":0},"schema":""}[119,121–123]. This method has been used by Pohl et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ces.2011.10.058","ISSN":"00092509","abstract":"Nanoparticles can be synthesized by precipitation. State-of-the-art is the precipitation of nanoparticles in stirred tanks or high-pressure T-mixers. The study presents two new reactor concepts for continuous precipitation of nanoparticles. Both of them utilize ultrasonic sound as a mixing accelerator. The first reactor has a conical chamber (10. mL), which is used to study the micromixing quality, the cavitation intensity and the precipitation of barium sulfate nanoparticles. The second reactor has a so-called cavitational chamber (2.5. mL), which is an optimized conical reactor. Both reactors are compared with each other with respect to the properties of the products. Additionally, the influence of the ultrasonic output from the transducer to the liquid and the feed rate are demonstrated. ? 2011 Elsevier Ltd.","author":[{"dropping-particle":"","family":"Pohl","given":"Birte","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Brenner","given":"Gunther","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Peuker","given":"Urs A.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-1","issue":"1","issued":{"date-parts":[["2012"]]},"note":"From Duplicate 1 (Experimental study of continuous ultrasonic reactors for mixing and precipitation of nanoparticles - Pohl, B.; Jamshidi, R.; Brenner, G.; Peuker, U. A.)\n\nWeissler reaction to measure intensity of the acoustic cavitation. In this Weissler-reaction, water is split into hydrogen and hydroxide radicals by ultrasonic output\n2H2O?????????????!\n2HU?2OHU-H2O2?H2\nH2O2?2I?-I2?2OH? I2?I?2I?\n3","page":"365-372","publisher":"Elsevier","title":"Experimental study of continuous ultrasonic reactors for mixing and precipitation of nanoparticles","type":"article-journal","volume":"69"},"uris":[""]}],"mendeley":{"formattedCitation":"[126]","plainTextFormattedCitation":"[126]","previouslyFormattedCitation":"[126]"},"properties":{"noteIndex":0},"schema":""}[126] to compare the cavitation intensity in two reactors consisting of a sonotrode attached to either a conical or a cavitation reaction chamber. Results showed that cavitation intensity was higher in the cavitation reaction chamber than in the conical reactors, as zones without ultrasonic irradiation might be present in the latter. Similar dosimetries can be used to quantify cavitation activity. Fricke dosimetry is based on the oxidation of Fe2+to Fe3+, whereas organic compounds produced by the reaction between salicylic acid and free radicals produced by ultrasound can be quantified by HPLC analysis. However, chemical dosimetries only allow the quantification of the overall cavitation activity in a given sonochemical reactor, the local cavitation activity cannot be quantified.The collapse of cavitation bubbles will also result in an increase of the fluid temperature, and hence recording the sonochemical reactor temperature change enables the quantification of cavitation activity ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2009.07.021","ISBN":"1385-8947","ISSN":"13858947","abstract":"Cavitation is a phenomenon having enormous potential for intensification of physical and chemical processing applications such as chemical synthesis, industrial wastewater treatment, cell disruption for release of intracellular enzymes, crystallization, extraction and leaching. However, the dynamic behavior of cavitational activity, especially in sonochemical reactors based on the use of ultrasonic irradiations, creates problems in proposing reliable design and operating strategies. The present work presents an overview of different techniques to understand the cavitational activity distribution in the reactor, highlighting the basic aspects, its applicability and relative merits/demerits. A detailed analysis of the literature has also been made with an aim of explaining the dependency of the cavitational activity on the design of sonochemical reactors and also the operating parameters. Recommendations for optimum operating parameters and design of reactor based on the experimental as well as theoretical analysis have been reported. Some trends in the future reactor designs useful in large scale applications have also been discussed. ? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2009"]]},"page":"26-36","title":"Design aspects of sonochemical reactors: Techniques for understanding cavitational activity distribution and effect of operating parameters","type":"article-journal","volume":"155"},"uris":[""]}],"mendeley":{"formattedCitation":"[119]","plainTextFormattedCitation":"[119]","previouslyFormattedCitation":"[119]"},"properties":{"noteIndex":0},"schema":""}[119]. A temperature probe can be used to obtain the temperature field, which in turn reveals the location of cavitation zones. However, the violent collapse of cavitation bubbles might damage the temperature probe, and their size restricts their applicability in microfluidics. A non-invasive approach to determine a qualitative temperature distribution in a reactor is based on thermal imaging. John et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.09.008","ISSN":"02552701","abstract":"A novel reactor was developed for ultrasound-assisted liquid–liquid extraction. This reactor design entails introducing short contact intervals for the microchannel tubing along the reactor plate channel to have a more focused transmission of the ultrasound. The non-contacted parts of the tubing are still under the influence of the ultrasound as a result of the pseudo-sonicated zone created by the adjacent intervals. The effect of introduction of these elements was first studied by comparing the thermal profiles with and without the presence of intervals and it was found that the maximum intensities along the channel become focused at these intervals. The influence of the intervals on a sonicated two-phase flow was also studied and revealed a repetitive splitting (at the intervals) and coalescence (downstream from the interval) of the emulsified aqueous phase. This dynamic change in the size of the emulsified aqueous phase introduces additional interfacial area and improves the mass transfer between the phases. The number of intervals was varied between three, five and seven. The five intervals showed the best performance. On comparing the five-interval design with a direct-contact design it was shown that the interval design gave the best improvement in yield for the process conditions studied.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"35-41","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid–liquid extraction with a novel interval-contact reactor","type":"article-journal","volume":"113"},"uris":[""]}],"mendeley":{"formattedCitation":"[106]","plainTextFormattedCitation":"[106]","previouslyFormattedCitation":"[106]"},"properties":{"noteIndex":0},"schema":""}[106] compared the temperature distribution inside a direct contact reactor and an interval-direct contact reactor using a thermal camera. For the interval contact reactor hot spots were observed at the intervals, whereas for the direct contact reactor hot spots were distributed on the entire surface of the micro-channel. Calorimetric measurements can be performed to determine the overall temperature increase in the fluidic channel, which in turn allows to estimate the power density ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2010.11.069","ISBN":"1385-8947","ISSN":"13858947","abstract":"The spectacular effects observed during acoustic cavitation phenomena have been successfully employed for a number of applications on laboratory scale of operation but a well defined design and scale up methodology is lacking. The present work aims at developing a unified approach for the selection of different operating and geometric parameters for large scale sonochemical reactors with a special emphasis on heterogeneous systems. In the case of heterogeneous systems, apart from optimum selection of operating and geometric parameters, it is also important to understand the mixing and hydrodynamic characteristics due to the presence of solid/gas phases in the liquid medium. Also the quantification of attenuation of the incident sound energy has been discussed, which can be important design consideration in heterogeneous systems. Recommendations have been made for optimum selection of frequency of irradiation and power dissipation rate/irradiation intensity as well as the liquid phase physicochemical properties for the given physicochemical transformation. The discussion also highlights' the recent advances in development of sonochemical reactors focusing on reactor geometry and location of transducers in batch and continuous scale of operation. ? 2010 Elsevier B.V.","author":[{"dropping-particle":"","family":"Gogate","given":"Parag R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sutkar","given":"Vinayak S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pandit","given":"Aniruddha B.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2011"]]},"page":"1066-1082","publisher":"Elsevier B.V.","title":"Sonochemical reactors: Important design and scale up considerations with a special emphasis on heterogeneous systems","type":"article-journal","volume":"166"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/B978-0-12-801530-8.00005-0","ISBN":"9780128015308","author":[{"dropping-particle":"","family":"Asakura","given":"Yoshiyuki","non-dropping-particle":"","parse-names":false,"suffix":""}],"chapter-number":"Chapter 15","container-title":"Sonochemistry and the Acoustic Bubble","id":"ITEM-3","issued":{"date-parts":[["2015"]]},"page":"119-150","publisher":"Elsevier Inc.","title":"Experimental Methods in Sonochemistry","type":"chapter"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/S1350-4177(03)00084-1","ISBN":"1350-4177","ISSN":"13504177","PMID":"12726951","abstract":"Fricke reaction, KI oxidation and decomposition of porphyrin derivatives by use of seven types of sonochemical apparatus in four different laboratories were examined in the range of frequency of 19.5 kHz to 1.2 MHz. The ultrasonic energy dissipated into an apparatus was determined also by calorimetry. Sonochemical efficiency of Fricke reaction and KI oxidation was defined as the number of reacted molecule per unit ultrasonic energy. The sonochemical efficiency is independent of experimental conditions such as the shape of sample cell and irradiation instruments, but depends on the ultrasonic frequency. We propose the KI oxidation dosimetry using 0.1 moldm-3KI solution as a standard method to calibrate the sonochemical efficiency of an individual reaction system. ? 2002 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Koda","given":"Shinobu","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kimura","given":"Takahide","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kondo","given":"Takashi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mitome","given":"Hideto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2003"]]},"note":"the aim of this paper is to establish a standard method to calibrate sonochemical efficiency. \nMeasurement of the calorimetric power: calorimetry is calculated from the temperature rise per sonication time at the time zero. \nDefinition of the sonochemical efficiency (ES-value) corresponds to the concentration of the compounds divided by the ultrasonic energy density (mol dm-3)/(J dm-3)","page":"149-156","title":"A standard method to calibrate sonochemical efficiency of an individual reaction system","type":"article-journal","volume":"10"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1016/j.ultsonch.2004.06.011","ISSN":"13504177","abstract":"Numerical simulations have been carried out in order to characterize the ultrasonic field propagation and to obtain the spatial distribution of the mechanical effect derived from it. The results have been compared with those obtained with different classical physical methods (calorimetry, aluminium foil erosion, thermal probes) and have given useful information about the influence of the presence of probes and auxiliary tools in the ultrasonic field. All these information have been used for the development of the Part II of this work: analysis of chemical effects, providing an accurate picture of the reaction environment in the sonoreactor used (20 kHz, 100 W supplied by Undatim) for further uses in sonoelectrochemical studies. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sáez","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Frías-Ferrer","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Iniesta","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"González-García","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Aldaz","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Riera","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-5","issued":{"date-parts":[["2005"]]},"page":"59-65","title":"Chacterization of a 20 kHz sonoreactor. Part I: analysis of mechanical effects by classical and numerical methods","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[30,45,122,123,127]","plainTextFormattedCitation":"[30,45,122,123,127]","previouslyFormattedCitation":"[30,45,122,123,127]"},"properties":{"noteIndex":0},"schema":""}[30,45,122,123,127], according toPcal=mcp?T?t,(2)where m is the mass of the liquid medium, and cp is the specific heat capacity of the medium at constant pressure, where cp is considered constant in the measured temperature range.While several experimental approaches exist to characterize sonochemical reactors, they are also associated with drawbacks, e.g., inserting temperature probes or hydrophones in a reactor might affect the cavitation activity distribution. As such, most experimental studies provide qualitative information, and in addition to them numerical simulations can be used to optimize the ultrasonic field distribution inside reactors and to increase the understanding of the ultrasound phenomena. For this, experimental studies serve as validation for the numerical methods. The most investigated effect of ultrasound by numerical simulation is the acoustic pressure distribution, which can be predicted by solving the Helmholtz equation ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1515/gps-2014-0052","abstract":"Possible drawbacks of microreactors are inefficient reactant mixing and the clogging of microchannels when solid-forming reactions are carried out or solid (catalysts) suspensions are used. Ultrasonic irradiation has been succesfully implemented for solving these problems in microreactor configurations ranging from capillaries immersed in ultrasonic baths to devices with miniaturized piezolelectric transducers. Moving forward in process intensification and sustainable development, the acoustic energy implementation requires a strategy to optimize the microreactor from an ultrasound viewpoint during its design. In this work, we present a simple analytical model that can be used as a guide to achieving a proper acoustic design of stacked microreactors. An example of this methodology was demonstrated through finite element analysis and it was compared with an experimental study found in the literature.","author":[{"dropping-particle":"","family":"Navarro-Brull","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Poveda","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ruiz-Femenia","given":"Rubén","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bonete","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ramis","given":"Jaime","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gómez","given":"Roberto","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Green Processing and Synthesis","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"311-320","title":"Guidelines for the design of efficient sono-microreactors","type":"article-journal","volume":"3"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-2","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2013.03.012","ISSN":"13504177","abstract":"This paper presents a three-dimensional numercial simulation of sonochemical degradation upon cavitational activity. The model relates the simulation of the acoustic pressure distribution to the sonochemical reaction rate. As a case study, the thermal degradation of carbon tetrachloride during sonication is studied in a tubular milliscale reactor. The model is used to optimize the reactor diameter, ultrasound frequency and power dissipated to the ultrasound transducers. The results indicate that multiple transducers at a moderate power level are more efficient than one transducer with high power level. Furthermore, the average cavity volume fraction is proposed as a reaction independent parameter to estimate the optimal reactor design. Within the results obtained in this paper, it appears possible to optimise reactor design based on this parameter. ? 2013 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Honings","given":"Aurélie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Degrève","given":"Jan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Van","family":"Gerven","given":"Tom","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2013"]]},"page":"1345-1352","publisher":"Elsevier B.V.","title":"Investigation of design parameters in ultrasound reactors with confined channels","type":"article-journal","volume":"20"},"uris":[""]}],"mendeley":{"formattedCitation":"[104,120,125]","plainTextFormattedCitation":"[104,120,125]","previouslyFormattedCitation":"[104,120,125]"},"properties":{"noteIndex":0},"schema":""}[104,120,125]. Rossi et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[120]","plainTextFormattedCitation":"[120]","previouslyFormattedCitation":"[120]"},"properties":{"noteIndex":0},"schema":""}[120] investigated the acoustic wave propagation and attenuation in a PMMA reactor by solving the Helmholtz equation:?2pa+km2pa=0,(3)with pa the pressure amplitude and km the complex wave number. The author defined a Dirichlet boundary condition at the wall and a pressure boundary condition at the source. Results showed that the transient cavitation zones can could be predicted by numerical simulation. Other primary and secondary effect of low frequency can be investigated ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2013.03.012","ISSN":"13504177","abstract":"This paper presents a three-dimensional numercial simulation of sonochemical degradation upon cavitational activity. The model relates the simulation of the acoustic pressure distribution to the sonochemical reaction rate. As a case study, the thermal degradation of carbon tetrachloride during sonication is studied in a tubular milliscale reactor. The model is used to optimize the reactor diameter, ultrasound frequency and power dissipated to the ultrasound transducers. The results indicate that multiple transducers at a moderate power level are more efficient than one transducer with high power level. Furthermore, the average cavity volume fraction is proposed as a reaction independent parameter to estimate the optimal reactor design. Within the results obtained in this paper, it appears possible to optimise reactor design based on this parameter. ? 2013 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Honings","given":"Aurélie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Degrève","given":"Jan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Van","family":"Gerven","given":"Tom","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2013"]]},"page":"1345-1352","publisher":"Elsevier B.V.","title":"Investigation of design parameters in ultrasound reactors with confined channels","type":"article-journal","volume":"20"},"uris":[""]}],"mendeley":{"formattedCitation":"[125]","plainTextFormattedCitation":"[125]","previouslyFormattedCitation":"[125]"},"properties":{"noteIndex":0},"schema":""}[125]. This work and those similar show that the numerical model, studied parameters and boundary conditions are linked and specific to the studied application and reactor design ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2013.03.012","ISSN":"13504177","abstract":"This paper presents a three-dimensional numercial simulation of sonochemical degradation upon cavitational activity. The model relates the simulation of the acoustic pressure distribution to the sonochemical reaction rate. As a case study, the thermal degradation of carbon tetrachloride during sonication is studied in a tubular milliscale reactor. The model is used to optimize the reactor diameter, ultrasound frequency and power dissipated to the ultrasound transducers. The results indicate that multiple transducers at a moderate power level are more efficient than one transducer with high power level. Furthermore, the average cavity volume fraction is proposed as a reaction independent parameter to estimate the optimal reactor design. Within the results obtained in this paper, it appears possible to optimise reactor design based on this parameter. ? 2013 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Honings","given":"Aurélie","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Degrève","given":"Jan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"Van","family":"Gerven","given":"Tom","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2013"]]},"page":"1345-1352","publisher":"Elsevier B.V.","title":"Investigation of design parameters in ultrasound reactors with confined channels","type":"article-journal","volume":"20"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2004.06.011","ISSN":"13504177","abstract":"Numerical simulations have been carried out in order to characterize the ultrasonic field propagation and to obtain the spatial distribution of the mechanical effect derived from it. The results have been compared with those obtained with different classical physical methods (calorimetry, aluminium foil erosion, thermal probes) and have given useful information about the influence of the presence of probes and auxiliary tools in the ultrasonic field. All these information have been used for the development of the Part II of this work: analysis of chemical effects, providing an accurate picture of the reaction environment in the sonoreactor used (20 kHz, 100 W supplied by Undatim) for further uses in sonoelectrochemical studies. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Sáez","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Frías-Ferrer","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Iniesta","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"González-García","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Aldaz","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Riera","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2005"]]},"page":"59-65","title":"Chacterization of a 20 kHz sonoreactor. Part I: analysis of mechanical effects by classical and numerical methods","type":"article-journal","volume":"12"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1021/acs.cgd.6b00696","ISBN":"1528-7483","ISSN":"15287505","abstract":"Continuous-flow crystallization of adipic acid in a millichannel chip equipped with a piezoelectric element is presented and investigated experimentally and numerically. A single, straight channel chip (cross section: 2 mm × 5 mm, length: 76 mm) made of glass, which is ultrasonically transparent, was designed and fabricated. The piezoelectric element allows studying the effect of different ultrasound frequencies in the kHz to MHz range. Ultrasound was applied in burst mode to reduce heating; this allowed operating at higher levels of input power. To accurately control the temperature of the fluid, Peltier elements were used to cool the bottom and top surfaces of the chip. Crystallization was performed in isothermal conditions, ensuring that the temperature and in turn the supersaturation were kept uniform along the channel. The effect of ultrasound frequency and sonication time was studied. Crystal size distributions at different operating conditions were obtained by laser diffraction. The distributions w...","author":[{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-3","issued":{"date-parts":[["2016"]]},"page":"4607-4619","title":"Investigation of the Effect of Ultrasound Parameters on Continuous Sonocrystallization in a Millifluidic Device","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[125,127,128]","plainTextFormattedCitation":"[125,127,128]","previouslyFormattedCitation":"[125,127,128]"},"properties":{"noteIndex":0},"schema":""}[125,127,128].4. ApplicationsSingle phase systems have, for a large part, been used in the detailed mechanism studies discussed in section 2.1. The concepts and effects, such as mixing, observed in these systems have inspired the use of these mechanisms for multiphase applications. Increased reaction rates with the application of ultrasound can be readily found in literature ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.05.157","ISSN":"13858947","abstract":"Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qiang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"April","issued":{"date-parts":[["2019"]]},"page":"68-78","publisher":"Elsevier","title":"Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature","type":"article-journal","volume":"374"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1002/cssc.201100369","ISBN":"1864-564X (Electronic)\\r1864-5631 (Linking)","ISSN":"1864564X","PMID":"22337650","abstract":"Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min(-1) range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.","author":[{"dropping-particle":"","family":"Hübner","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kressirer","given":"S.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kralisch","given":"D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bludszuweit-Philipp","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lukow","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?nich","given":"I.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schilling","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hieronymus","given":"H.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liebner","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"J?hnisch","given":"K.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemSusChem","id":"ITEM-2","issued":{"date-parts":[["2012"]]},"page":"279-288","title":"Ultrasound and microstructures-a promising combination?","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[67,109]","plainTextFormattedCitation":"[67,109]","previouslyFormattedCitation":"[67,109]"},"properties":{"noteIndex":0},"schema":""}[67,109], which is usually ascribed to effects such as streaming, increased interfacial area or the combination of both. On the other hand, the extent to which each of these effects contribute along with a detailed study of the mechanisms in multiphase systems, very little is known. This section contains the most relevant studies on the roles that ultrasonic mechanisms play in ultrasonic flow reactors along with several applications.4.1. Gas–-liquid systemsDong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-1","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]}],"mendeley":{"formattedCitation":"[38]","plainTextFormattedCitation":"[38]","previouslyFormattedCitation":"[38]"},"properties":{"noteIndex":0},"schema":""}[38] characterized the mechanisms behind a 3– to 20-fold increase in mass transfer of a directly sonicated microreactor over that of unsonicated conditions. For gas–-liquid Taylor flow in a microchannel, when the applied ultrasonic power is increased above certain threshold powers, gas bubbles in the channel start to oscillate in different modes. For each surface mode, the specific surface area can be described by the wavelength and amplitude of the oscillating interface, knowing the geometry of the bubble. For a bubble oscillating under the Faraday capillary mode, the specific surface area increases significantly from 30% to –160% with increasing power, however the onset of this increase was limited by the channel size. As mentioned earlier for channels with a smaller cross section, more power is required to overcome the threshold to initiate surface wave oscillations, due to the confinement effect ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2006.10.013","ISSN":"13504177","abstract":"Dynamic motions of gas bubble confined in a microspace, i.e., in a channel of a microreactor, were observed with a video microscope and stroboscopic technique using a light emitting diode operated in a pulsed mode. There are many important phenomena related to the bubble dynamics synchronized with ultrasonic wave and continued for more than a few minutes. With the stroboscopic technique, the time-expanded bubble motions synchronized with ultrasound wave and the real time background images can be simultaneously observed. A number of interesting phenomena resulting from the dynamic motions of a microbubble in a microspace were observed; nonspherical bubble oscillation, rectified diffusion, emergence of cavitation, and microstreaming of different patterns depending on the input power of ultrasound. The observation technique described in this investigation could be a convenient tool for taming the bubble under a microscope to investigate the bubble dynamics in detail. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Iida","given":"Yasuo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tuziuti","given":"Toru","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yasui","given":"Kyuichi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Towata","given":"Atsuya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kozuka","given":"Teruyuki","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"621-626","title":"Bubble motions confined in a microspace observed with stroboscopic technique","type":"article-journal","volume":"14"},"uris":[""]}],"mendeley":{"formattedCitation":"[66]","plainTextFormattedCitation":"[66]","previouslyFormattedCitation":"[66]"},"properties":{"noteIndex":0},"schema":""}[66], as explained in section 2.1.Cavitation microstreaming was also observed and characterized by streaming velocities measurements using streak photography for the same system under sonication. Two additional vortices associated with cavitation microstreaming were shown to interact with the regular Taylor flow pattern, which resulted in vigorous and dynamic streaming that increased with power. Using the Higbie penetration model ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Higbie R.","given":"","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Trans. Am. Inst. Chem. Eng.","id":"ITEM-1","issued":{"date-parts":[["1935"]]},"page":"365–389","title":"The rate of absorption of a pure gas into a still liquid during short periods of exposure","type":"article-journal","volume":"31"},"uris":[""]}],"mendeley":{"formattedCitation":"[129]","plainTextFormattedCitation":"[129]","previouslyFormattedCitation":"[129]"},"properties":{"noteIndex":0},"schema":""}[129], the mass transfer coefficient under sonication (kL') could be described by the streaming velocity (UA) at the gas–-liquid interface:kL'= US+UAUSkL,(4)with US the bubble’s slip velocity and kL the mass transfer coefficient in silent conditions. Mixing due to cavitation microstreaming would immediately enhance mass transfer from the onset of ultrasound, with a more profound effect on channels with larger diameters, since there is less recirculation to begin with. Whereas an increase in specific surface area would only occur in after a certain amount of applied power, especially for smaller channels. Eventually both enhancement, due to cavitation microstreaming and increased specific surface area, plateaus to within the same range for all the channels sizes with increasing power. For a gas–-liquid Taylor system, Tandiono et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1073/pnas.1019623108","ISBN":"0780341538","ISSN":"0027-8424","PMID":"21447713","abstract":"One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk liquid. We present here a realization of sonoluminescence and sonochemistry created from bubbles confined within a narrow channel of polydimethylsiloxane-based microfluidic devices. In the microfluidics channels, the bubbles form a planar/pancake shape. During bubble collapse we find the formation of OH radicals and the emission of light. The chemical reactions are closely confined to gas-liquid interfaces that allow for spatial control of sonochemical reactions in lab-on-a-chip devices. The decay time of the light emitted from the sonochemical reaction is several orders faster than that in the bulk liquid. Multibubble sonoluminescence emission in contrast vanishes immediately as the sound field is stopped.","author":[{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"S.-W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"D. S. W.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"E.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Wong","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dumke","given":"R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"C.-D.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Proceedings of the National Academy of Sciences","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"5996-5998","title":"Sonochemistry and sonoluminescence in microfluidics","type":"article-journal","volume":"108"},"uris":[""]}],"mendeley":{"formattedCitation":"[76]","plainTextFormattedCitation":"[76]","previouslyFormattedCitation":"[76]"},"properties":{"noteIndex":0},"schema":""}[76] found that cavitation activity was more extensive pronounced near the gas–-liquid interface compared to that of the rest of the liquid slug. From a sequence of high speed images, it was seen that capillary waves at the interface would entrap small gas bubbles, these bubbles would then serve as nuclei for cavitation bubbles. With the introduction of a gas phase the effects of ultrasound can be enhanced significantly, a challenge that has proven difficult due to the confined space and reduced volume of microchannels. Zhao et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ces.2018.04.042","ISSN":"00092509","abstract":"The synergistic effects of gas agitation and ultrasound on mass transfer between immiscible liquids were investigated in an in-house made ultrasonic microreactor. With the introduction of inert gas (N2), a three-phase slug flow with slug bubbles either dispersed in continuous aqueous phase or encapsulated in oil plugs was observed. Under ultrasound irradiation, slug bubbles underwent surface wave oscillation and induced agitation in microchannel. In addition, microbubbles were generated by acoustic cavitation, oscillating intensely and resulting in the formation of O/W emulsion. Bubble oscillation (i.e., slug bubbles and microbubbles) as well as emulsification promoted liquid-liquid mass transfer significantly. Extraction of vanillin from aqueous solution to toluene was employed to demonstrate the mass transfer enhancement. Compared with silent operation, both mass transfer coefficient and extraction efficiency were largely improved by the combined use of gas agitation and ultrasound. With gas flow velocity being 0.005–0.083 m/s at fixed ultrasound power of 30 W, the overall mass transfer coefficients ranged from 0.047 s?1 to 0.429 s?1, which was 2.33–17.20 times larger than the corresponding liquid-liquid two-phase process without ultrasound irradiation.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Yanyan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"122-134","publisher":"Elsevier Ltd","title":"Intensification of liquid-liquid two-phase mass transfer by oscillating bubbles in ultrasonic microreactor","type":"article-journal","volume":"186"},"uris":[""]}],"mendeley":{"formattedCitation":"[39]","plainTextFormattedCitation":"[39]","previouslyFormattedCitation":"[39]"},"properties":{"noteIndex":0},"schema":""}[39] were able to utilize this for vanillin extraction, nitrogen gas was introduced to improve mass transfer even further over that of typical liquid–-liquid extraction under sonication, which is discussed in the following subsection. When a third gaseous phase is introduced to a sonicated liquid–-liquid system, surface wave oscillation as well as acoustic streaming at the gas–-liquid interface enhances mass transfer in a similar way as for gas-liquid systems ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ces.2018.04.042","ISSN":"00092509","abstract":"The synergistic effects of gas agitation and ultrasound on mass transfer between immiscible liquids were investigated in an in-house made ultrasonic microreactor. With the introduction of inert gas (N2), a three-phase slug flow with slug bubbles either dispersed in continuous aqueous phase or encapsulated in oil plugs was observed. Under ultrasound irradiation, slug bubbles underwent surface wave oscillation and induced agitation in microchannel. In addition, microbubbles were generated by acoustic cavitation, oscillating intensely and resulting in the formation of O/W emulsion. Bubble oscillation (i.e., slug bubbles and microbubbles) as well as emulsification promoted liquid-liquid mass transfer significantly. Extraction of vanillin from aqueous solution to toluene was employed to demonstrate the mass transfer enhancement. Compared with silent operation, both mass transfer coefficient and extraction efficiency were largely improved by the combined use of gas agitation and ultrasound. With gas flow velocity being 0.005–0.083 m/s at fixed ultrasound power of 30 W, the overall mass transfer coefficients ranged from 0.047 s?1 to 0.429 s?1, which was 2.33–17.20 times larger than the corresponding liquid-liquid two-phase process without ultrasound irradiation.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Yanyan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"122-134","publisher":"Elsevier Ltd","title":"Intensification of liquid-liquid two-phase mass transfer by oscillating bubbles in ultrasonic microreactor","type":"article-journal","volume":"186"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1038/srep12572","ISSN":"20452322","abstract":"We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process.","author":[{"dropping-particle":"","family":"Xie","given":"Yuliang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chindam","given":"Chandraprakash","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nama","given":"Nitesh","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yang","given":"Shikuan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lu","given":"Mengqian","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yanhui","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mai","given":"John D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Costanzo","given":"Francesco","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Scientific Reports","id":"ITEM-2","issue":"12572","issued":{"date-parts":[["2015"]]},"page":"1-9","publisher":"Nature Publishing Group","title":"Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-3","itemData":{"abstract":"According to various embodimets, a microfluidic device may be provided. The microfluidic device may include: a microfluidic channel with a plurality of inlets for fluids; and an ultrasound emitter configured to emit ultrasonic waves to the microfluidic channel. According to various embodiments, a second inlet of the plurality of inlets may include or may be an inlet for a liquid. According to various embodiments, a third inlet of the plurality of inlets may include or may be an inlet for a liquid","author":[{"dropping-particle":"","family":"Tandiono","given":"Tandiono","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Siew-Wan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ow","given":"Siak-Wei Dave","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Claus-Dieter","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-3","issued":{"date-parts":[["2013"]]},"number":"WO2013/184075 A1","publisher-place":"Singapore","title":"Microfluidic devices and methods for providing an emulsion of a plurality of fluids","type":"patent"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1121/1.4900279","abstract":"In this study, two immiscible liquids in a microfluidics channel has been successfully emulsified by acoustic cavitation bubbles. These bubbles are generated by the attached piezo transducers which are driven to oscillate at resonant frequency of the system (about 100 kHz) [1, 2]. The bubbles oscillate and induce strong mixing in the microchamber. They induce the rupture of the liquid thin layer along the bubble surface due to the high shear stress and fast liquid jetting at the interface. Also, they cause the big droplets to fragment into small droplets. Both water-in-oil and oil-in-water emulsions with viscosity ratio up to 1000 have been produced using this method without the application of surfactant. The system is highly efficient as submicron monodisperse emulsions (especially for water-in-oil emulsion) could be created within milliseconds. It is found that with a longer ultrasound exposure, the size of the droplets in the emulsions decreases, and the uniformity of the emulsion increases. Reference: [1] Tandiono, SW Ohl et al., “Creation of cavitation activity in a microfluidics device through acoustically driven capillary waves,” Lab Chip 10, 1848–1855 (2010). [2] Tandiono, SW Ohl et al., “Sonochemistry and sonoluminescence in microfluidics,” Proc. Natl. Acad. Sci. U.S.A. 108(15), 5996–5998 (2011)","author":[{"dropping-particle":"","family":"Ohl","given":"Siew-Wan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tandiono","given":"","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Klaseboer","given":"Evert","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Siak Wei Ow","given":"Dave","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Choo","given":"Andre","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Li","given":"Fenfang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ohl","given":"Claus-Dieter","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"The Journal of the Acoustical Society of America","id":"ITEM-4","issued":{"date-parts":[["2014"]]},"page":"2289","title":"Surfactant-free emulsification in microfluidics using strongly oscillating bubbles","type":"article-journal","volume":"136"},"uris":[""]}],"mendeley":{"formattedCitation":"[39,130–132]","plainTextFormattedCitation":"[39,130–132]","previouslyFormattedCitation":"[39,130–132]"},"properties":{"noteIndex":0},"schema":""}[39,130–132].Navarro-Brull et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.iecr.7b03876","ISSN":"15205045","abstract":"Channeling of gas can reduce mass transfer performance in multiphase micropacked-bed reactors. Viscous and capillary forces cause this undesired and often unpredictable phenomenon in systems with catalyst particle sizes of hundreds of micrometers. In this work, we acoustically modify flow in a micropacked-bed reactor to reduce gas channeling by applying high-power sonication at low ultrasonic frequencies (～40 kHz). Experimental residence time distributions reveal two orders of magnitude reduction in dispersion with ultrasound, allowing for nearly plug-flow behavior at high flow rates in the bed. Sonication appears to partially fluidize the packed-bed under pressurized cocurrent two-phase flow, effectively improving dispersion characteristics.","author":[{"dropping-particle":"","family":"Navarro-Brull","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"Andrew R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Jisong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gómez","given":"Roberto","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Industrial and Engineering Chemistry Research","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"122-128","title":"Reduction of Dispersion in Ultrasonically-Enhanced Micropacked Beds","type":"article-journal","volume":"57"},"uris":[""]}],"mendeley":{"formattedCitation":"[133]","plainTextFormattedCitation":"[133]","previouslyFormattedCitation":"[133]"},"properties":{"noteIndex":0},"schema":""}[133] utilized ultrasound to improve liquid-gas dispersion throughout their micropacked-bed reactor, the authors suggest that the motion of particles with sonication reduces gas channeling through effectively fluidizing the packed bed. Results show a reduction in axial dispersion of two orders of magnitude with ultrasound.4.2. Liquid–-liquid systemsWhen liquid–-liquid extraction is carried out in a microchannel with the application of ultrasound the extraction efficiency is significantly increased ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.16010","abstract":"The effects of ultrasound on the hydrodynamic and mass transfer behaviors of immiscible liquid–liquid two-phase flow was investigated in a domestic ultrasonic microreactor. Under ultrasonic irradiation, cavitation bubble was generated and underwent violent oscillation. Emulsification of immiscible phases was initiated by virtue of oscillating bubbles shuttling through the water/oil interface. The pressure drop was found to decrease with increasing ultrasound power, with a maximum decrement ratio of 12% obtained at power 30 W. The mass transfer behavior was characterized by extraction of Rhodamine B from water to 1-octanol. An enhancement factor of 1.3–2.2 on the overall mass-transfer coef- ficient was achieved under sonication. The mass transfer performance was comparable to passive microreactor at simi- lar energy dissipation rate (61–184 W/kg). The extraction equilibrium was reached under a total flow velocity 0.01 m/s and input power 20 and 30 W, exhibiting its potential use in liquid-liquid extraction process.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chaoqun","given":"Yao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wen","given":"Zhenghui","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2018"]]},"page":"1412-1423","publisher":"AIChE Journal. 64","title":"Liquid-Liquid Two-Phase Flow in Ultrasonic Microreactors: Cavitation, Emulsification and Mass Transfer Enhancement","type":"article-journal","volume":"64"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cep.2016.01.003","ISSN":"02552701","abstract":"A new method to apply ultrasound to a microchannel for liquid-liquid extraction was explored. The microchannel tubes are subjected to the ultrasound by direct contact with the transducer without the presence of a liquid medium. The design was constructed with the objectives of reproducibility, proper control of the ultrasound parameters and visibility of the behaviour of the two phase flow under the influence of ultrasound throughout the length of the channel. Two mechanisms of emulsion formation were observed. The effectiveness of the system under the influence of various operating and design parameters was quantified by calculating the yields of the two phase hydrolysis reaction of p-nitrophenyl acetate. The behaviour under various frequencies and amplitude was explored. At a frequency of 20.3. kHz, amplitude of 840. mV and flow rate of 0.1. ml/min the highest increase in yield was observed, which was almost 2.5 times that of the silent condition. A comparison was also made against silent batch and flow conditions to determine the actual effectiveness of the system. To obtain an identical yield of 75% the required residence time could be reduced by a factor of 20 in the sonicated flow condition compared to the silent batch condition.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-2","issued":{"date-parts":[["2016"]]},"page":"37-46","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid-liquid extraction in microchannels-A direct contact method","type":"article-journal","volume":"102"},"uris":[""]}],"mendeley":{"formattedCitation":"[108,134]","plainTextFormattedCitation":"[108,134]","previouslyFormattedCitation":"[108,134]"},"properties":{"noteIndex":0},"schema":""}[108,134]. Although the same phenomena can be found in both gas–-liquid and liquid–-liquid systems, the way these phenomena enhance mass transfer differ to a certain extent. When ultrasound is applied to a liquid–-liquid system, cavitation bubbles emulsify the immiscible liquids, significantly increasing the surface area available for mass transfer. Although the exact mechanism of how cavitation leads to emulsification is still unclear, there is no doubt that it plays a key role. Zhao et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.16010","abstract":"The effects of ultrasound on the hydrodynamic and mass transfer behaviors of immiscible liquid–liquid two-phase flow was investigated in a domestic ultrasonic microreactor. Under ultrasonic irradiation, cavitation bubble was generated and underwent violent oscillation. Emulsification of immiscible phases was initiated by virtue of oscillating bubbles shuttling through the water/oil interface. The pressure drop was found to decrease with increasing ultrasound power, with a maximum decrement ratio of 12% obtained at power 30 W. The mass transfer behavior was characterized by extraction of Rhodamine B from water to 1-octanol. An enhancement factor of 1.3–2.2 on the overall mass-transfer coef- ficient was achieved under sonication. The mass transfer performance was comparable to passive microreactor at simi- lar energy dissipation rate (61–184 W/kg). The extraction equilibrium was reached under a total flow velocity 0.01 m/s and input power 20 and 30 W, exhibiting its potential use in liquid-liquid extraction process.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chaoqun","given":"Yao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wen","given":"Zhenghui","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2018"]]},"page":"1412-1423","publisher":"AIChE Journal. 64","title":"Liquid-Liquid Two-Phase Flow in Ultrasonic Microreactors: Cavitation, Emulsification and Mass Transfer Enhancement","type":"article-journal","volume":"64"},"uris":[""]}],"mendeley":{"formattedCitation":"[134]","plainTextFormattedCitation":"[134]","previouslyFormattedCitation":"[134]"},"properties":{"noteIndex":0},"schema":""}[134] observed that as cavitation bubbles oscillate vigorously within a microchannel, they often shuttle through the interface of the two immiscible fluids carrying with them a small film of the organic phase (in this case 1-octane) into the aqueous phase (in this case water). The unstable cavitation bubble then breaks up this film to form smaller emulsion droplets within the aqueous slug. Stepi?nik Perdih et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2018.10.003","ISSN":"18732828","PMID":"11931755","abstract":"Today emulsion preparation is receiving a lot of scientific attention, since emulsions are playing an essential role in many of the big industries, such as food, pharmaceutical or cosmetic industry. One of the most promising techniques for emulsion preparation is ultrasound emulsification. The purpose of this study is to expand the knowledge on the ultrasonically assisted emulsification model, that has not been amended since 1978. The model explains that oil-in-water emulsion formation is a two-step process. Firstly, the surface of the oil phase is disturbed and separated by the acoustic waves. Secondly, cavitation implosions further disrupt and disperse oil drops. We have used a high-speed camera to closely observe oil-in-water emulsion formation. The images show, that the ultrasound emulsification process is profoundly more complex. While the first and the last step of emulsion formation are the same as believed until now, additional intermediate stages of water-in-oil and even oil-in-water-in-oil occur.","author":[{"dropping-particle":"","family":"Stepi?nik Perdih","given":"Tadej","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zupanc","given":"Mojca","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dular","given":"Matev?","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"298-304","publisher":"Elsevier","title":"Revision of the mechanisms behind oil-water (O/W) emulsion preparation by ultrasound and cavitation","type":"article-journal","volume":"51"},"uris":[""]}],"mendeley":{"formattedCitation":"[135]","plainTextFormattedCitation":"[135]","previouslyFormattedCitation":"[135]"},"properties":{"noteIndex":0},"schema":""}[135] propose that when cavitation bubbles in the aqueous phase (in this case water) implode near the aqueous-organic interface (in this case sunflower oil), microjets propel water through the interface into the bulk of the organic phase. Thereafter, due to interface instability near the initial implosion, a small amount of the organic phase containing the dispersed aqueous phase separates from the bulk forming a droplet in the aqueous phase, w. Which, once exposed to ultrasound, breaks into smaller droplets until small enough to be freely immersed in the aqueous phase forming an emulsion. The ultrasonic flow-through cell reactor, depicted in Figure 4c, was able to emulsify liquids under contamination free conditions, producing vegetable oil-in-water emulsions with Sauter diameters of 0.5 ?m, as well as spherical particles, from a poly(lactic-co-glycolic acid) (PLGA) solution in dichloromethane, with volume mean diameters less than 0.5 ?m ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2004.10.004","ISSN":"13504177","abstract":"A novel concept was developed here for the continuous, contact- and contamination-free treatment of fluid mixtures with ultrasound. It is based on exciting a steel jacket with an ultrasonic transducer, which transmitted the sound waves via pressurised water to a glass tube installed inside the jacket. Thus, no metallic particles can be emitted into the sonicated fluid, which is a common problem when a sonotrode and a fluid are in direct contact. Moreover, contamination of the fluid from the environment can be avoided, making the novel ultrasonic flow-through cell highly suitable for aseptic production of pharmaceutical preparations. As a model system, vegetable oil-in-water emulsions, fed into the cell as coarse pre-emulsions, were studied. The mean droplet diameter was decreased by two orders of magnitude yielding Sauter diameters of 0.5 μm and below with good repeatability. Increasing the residence time in the ultrasonic field and the sonication power both decreased the emulsion mean diameter. Furthermore, the ultrasonic flow-through cell was found to be well suited for the production of nanoparticles of biodegradable polymers by the emulsion-solvent extraction/ evaporation method. Here, perfectly spherical particles of a volume mean diameter of less than 0.5 μm could be prepared. In conclusion, this novel technology offers a pharmaceutically interesting platform for nanodroplet and nanoparticle production and is well suited for aseptic continuous processing. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Freitas","given":"Sergio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hielscher","given":"Gerhard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merkle","given":"Hans P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gander","given":"Bruno","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2006"]]},"page":"76-85","title":"Continuous contact- and contamination-free ultrasonic emulsification - A useful tool for pharmaceutical development and production","type":"article-journal","volume":"13"},"uris":[""]}],"mendeley":{"formattedCitation":"[98]","plainTextFormattedCitation":"[98]","previouslyFormattedCitation":"[98]"},"properties":{"noteIndex":0},"schema":""}[98]. Recently John et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.09.008","ISSN":"02552701","abstract":"A novel reactor was developed for ultrasound-assisted liquid–liquid extraction. This reactor design entails introducing short contact intervals for the microchannel tubing along the reactor plate channel to have a more focused transmission of the ultrasound. The non-contacted parts of the tubing are still under the influence of the ultrasound as a result of the pseudo-sonicated zone created by the adjacent intervals. The effect of introduction of these elements was first studied by comparing the thermal profiles with and without the presence of intervals and it was found that the maximum intensities along the channel become focused at these intervals. The influence of the intervals on a sonicated two-phase flow was also studied and revealed a repetitive splitting (at the intervals) and coalescence (downstream from the interval) of the emulsified aqueous phase. This dynamic change in the size of the emulsified aqueous phase introduces additional interfacial area and improves the mass transfer between the phases. The number of intervals was varied between three, five and seven. The five intervals showed the best performance. On comparing the five-interval design with a direct-contact design it was shown that the interval design gave the best improvement in yield for the process conditions studied.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"35-41","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid–liquid extraction with a novel interval-contact reactor","type":"article-journal","volume":"113"},"uris":[""]}],"mendeley":{"formattedCitation":"[106]","plainTextFormattedCitation":"[106]","previouslyFormattedCitation":"[106]"},"properties":{"noteIndex":0},"schema":""}[106] were able to improve the performance of a liquid–-liquid extraction process to their previous work ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.01.003","ISSN":"02552701","abstract":"A new method to apply ultrasound to a microchannel for liquid-liquid extraction was explored. The microchannel tubes are subjected to the ultrasound by direct contact with the transducer without the presence of a liquid medium. The design was constructed with the objectives of reproducibility, proper control of the ultrasound parameters and visibility of the behaviour of the two phase flow under the influence of ultrasound throughout the length of the channel. Two mechanisms of emulsion formation were observed. The effectiveness of the system under the influence of various operating and design parameters was quantified by calculating the yields of the two phase hydrolysis reaction of p-nitrophenyl acetate. The behaviour under various frequencies and amplitude was explored. At a frequency of 20.3. kHz, amplitude of 840. mV and flow rate of 0.1. ml/min the highest increase in yield was observed, which was almost 2.5 times that of the silent condition. A comparison was also made against silent batch and flow conditions to determine the actual effectiveness of the system. To obtain an identical yield of 75% the required residence time could be reduced by a factor of 20 in the sonicated flow condition compared to the silent batch condition.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"37-46","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid-liquid extraction in microchannels-A direct contact method","type":"article-journal","volume":"102"},"uris":[""]}],"mendeley":{"formattedCitation":"[108]","plainTextFormattedCitation":"[108]","previouslyFormattedCitation":"[108]"},"properties":{"noteIndex":0},"schema":""}[108] by focusing the applied ultrasound directly only at short intervals, as mentioned in section 3.1. This would allow for the aqueous and organic phases, to periodically emulsify and then coalesce resulting in an increase of interfacial area improving mass transfer of the system. From Figure 5a clear increase in extraction performance is observed when switching from batch to continuous flow, which is significantly increased with the application of ultrasound. Later the interval contact and hybrid rector was designed to improve performance, both showing similar and improved results ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115].Figure 5. Reaction yield for the hydrolysis of p-nitrophenyl in a stirred batch reactor, unsonicated (silent) flow reactor, direct contact ultrasonic flow reactor and the five interval contact ultrasonic flow reactor, reproduced with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.09.008","ISSN":"02552701","abstract":"A novel reactor was developed for ultrasound-assisted liquid–liquid extraction. This reactor design entails introducing short contact intervals for the microchannel tubing along the reactor plate channel to have a more focused transmission of the ultrasound. The non-contacted parts of the tubing are still under the influence of the ultrasound as a result of the pseudo-sonicated zone created by the adjacent intervals. The effect of introduction of these elements was first studied by comparing the thermal profiles with and without the presence of intervals and it was found that the maximum intensities along the channel become focused at these intervals. The influence of the intervals on a sonicated two-phase flow was also studied and revealed a repetitive splitting (at the intervals) and coalescence (downstream from the interval) of the emulsified aqueous phase. This dynamic change in the size of the emulsified aqueous phase introduces additional interfacial area and improves the mass transfer between the phases. The number of intervals was varied between three, five and seven. The five intervals showed the best performance. On comparing the five-interval design with a direct-contact design it was shown that the interval design gave the best improvement in yield for the process conditions studied.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"35-41","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid–liquid extraction with a novel interval-contact reactor","type":"article-journal","volume":"113"},"uris":[""]}],"mendeley":{"formattedCitation":"[106]","plainTextFormattedCitation":"[106]","previouslyFormattedCitation":"[106]"},"properties":{"noteIndex":0},"schema":""}[106] and ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.01.003","ISSN":"02552701","abstract":"A new method to apply ultrasound to a microchannel for liquid-liquid extraction was explored. The microchannel tubes are subjected to the ultrasound by direct contact with the transducer without the presence of a liquid medium. The design was constructed with the objectives of reproducibility, proper control of the ultrasound parameters and visibility of the behaviour of the two phase flow under the influence of ultrasound throughout the length of the channel. Two mechanisms of emulsion formation were observed. The effectiveness of the system under the influence of various operating and design parameters was quantified by calculating the yields of the two phase hydrolysis reaction of p-nitrophenyl acetate. The behaviour under various frequencies and amplitude was explored. At a frequency of 20.3. kHz, amplitude of 840. mV and flow rate of 0.1. ml/min the highest increase in yield was observed, which was almost 2.5 times that of the silent condition. A comparison was also made against silent batch and flow conditions to determine the actual effectiveness of the system. To obtain an identical yield of 75% the required residence time could be reduced by a factor of 20 in the sonicated flow condition compared to the silent batch condition.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"37-46","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid-liquid extraction in microchannels-A direct contact method","type":"article-journal","volume":"102"},"uris":[""]}],"mendeley":{"formattedCitation":"[108]","plainTextFormattedCitation":"[108]","previouslyFormattedCitation":"[108]"},"properties":{"noteIndex":0},"schema":""}[108], copyright Elsevier.4.3. Liquid–-solid systemsWhen solid particles enter the system as a product or byproduct, particle deposition on the channel walls that can lead to channel fouling becomes a serious issue. Extensive research has been carried using ultrasound for organic and material synthesis as well as crystallization to prevent or at least mitigate this problem, with promising results ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/op100154d","ISSN":"10836160","abstract":"We investigate the mechanisms that govern plugging in microreactors during Pd-catalyzed amination reactions. Both bridging and constriction were shown to be important mechanisms that lead to clogging in our system and greatly limited the utility of microsystems for this class of reactions. On the basis of these observations, several approaches were engineered to overcome the challenge of plugging and to enable the continuous-flow synthesis of a biarylamine. Bridging could be eliminated with acoustic irradiation while constriction was managed via fluid velocity and the prediction of growth rates. ? 2010 American Chemical Society.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-1","issued":{"date-parts":[["2010"]]},"page":"1347-1357","title":"Overcoming the challenges of solid bridging and constriction during Pd-catalyzed C-N bond formation in microreactors","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/c1lc20337a","ISSN":"14730189","abstract":"We present a general inexpensive method for realizing a Teflon stack microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The microreactors are demonstrated with palladium-catalyzed C-N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. Investigations of the ultrasonic waveform applied by the piezoelectric actuator reveal an optimal value of 50 kHz at a load power of 30 W. Operating the system at these conditions, the newly developed Teflon microreactor handles the insoluble solids formed and no clogging is observed. The investigated reactions reach full conversion in very short reaction times and high isolated yields are obtained (>95% yield).","author":[{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heider","given":"Patrick L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issue":"15","issued":{"date-parts":[["2011"]]},"page":"2488-2492","title":"A Teflon microreactor with integrated piezoelectric actuator to handle solid forming reactions","type":"article-journal","volume":"11"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-3","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]},{"id":"ITEM-5","itemData":{"DOI":"10.1016/j.cep.2019.03.017","ISSN":"02552701","abstract":"Crystallization is an important and widely used separation technique in the chemical and pharmaceutical industry. Control of the final particle properties is of great importance for these industries. The application of ultrasound in these crystallization processes, also referred to as sonocrystallization, has shown to impact nucleation, crystal growth and fragmentation. As a result this technology has potential to control the final particle size, shape and polymorphic form. This review provides a comprehensive overview of the recent advances in sonocrystallization. It reviews the observed effects of ultrasound on the different stages of the crystallization process. Recent insights in the mechanism behind these effects are discussed as well. Finally, guidelines for the operating conditions, such as ultrasonic frequency, power, type of cavitation bubbles, time window and moment of application are formulated.","author":[{"dropping-particle":"","family":"Jordens","given":"Jeroen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gielen","given":"Bjorn","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xiouras","given":"Christos","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hussain","given":"Mohammed Noorul","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Stefanidis","given":"Georgios D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Thomassen","given":"Leen C.J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing - Process Intensification","id":"ITEM-5","issued":{"date-parts":[["2019"]]},"page":"130-154","title":"Sonocrystallisation: Observations, theories and guidelines","type":"article-journal","volume":"139"},"uris":[""]},{"id":"ITEM-6","itemData":{"DOI":"10.1016/j.ultsonch.2006.12.004","ISSN":"13504177","abstract":"The positive influence of ultrasound (US) on crystallization processes is shown by the dramatic reduction of the induction period, supersaturation conditions and metastable zone width. Manipulation of this influence can be achieved by changing US-related variables such as frequency, intensity, power and even geometrical characteristics of the ultrasonic device (e.g. horn type size). The volume of the sonicated solution and irradiation time are also variables to be optimized in a case-by-case basis as the mechanisms of US action on crystallization remain to be established. Nevertheless, the results obtained so far make foreseeable that crystal size distribution, and even crystal shape, can be 'tailored' by appropriate selection of the sonication conditions. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Luque de Castro","given":"M. D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Priego-Capote","given":"F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-6","issued":{"date-parts":[["2007"]]},"page":"717-724","title":"Ultrasound-assisted crystallization (sonocrystallization)","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-7","itemData":{"DOI":"10.1021/op200348t","ISSN":"10836160","abstract":"The management of solid compounds is a major challenge facing the upstream, continuous processing of pharmaceuticals and fine chemicals. Many reactions relevant to fine chemical production either react with or form insoluble materials, which become problematic in continuous flow microreactors. The deposition, growth, or bridging of compounds can limit fluid flow from the micro-to the mesoscale, and thereby render continuous reactors inoperable. A comprehensive approach for managing solids consists of solids identification, the development of the root failure mechanism(s), and the application of active and passive techniques for the prevention and remediation. This review examines the basic principles of microreactor design for reactions that involve solids, toward the goal of performing the continuous flow processing of fine chemicals.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-7","issued":{"date-parts":[["2012"]]},"note":"Liquid-solid, clogging mechanism prevention","page":"870-887","title":"Managing Solids in Microreactors for the Upstream Continuous Processing of Fine Chemicals","type":"article-journal","volume":"16"},"uris":[""]},{"id":"ITEM-8","itemData":{"DOI":"10.1556/1846.2015.00001","ISSN":"20630212","abstract":"Flow chemistry has emerged as the enabling field of high-throughput, data-driven discovery, and process chemistry, yet solids handling remains its key challenge. Insoluble salt by-products can stop flow, fluctuate reagent concentrations in reactors, and cost unexpected time and materials consumptions. The clogging of perfluoroalkoxy (PFA) tubing, stainless steel (SS) tubing, and a silicon microreactor by NaCl during a Pd- catalyzed amination using XPhos ligand was each studied. Our goal of understanding the appropriate reactor design provides in-depth analyses of constriction and mechanical entrapment. Calculations of Stokes number (St)<1 revealed that NaCl particle depositions were independent of the reactor materials. Analyses of the clogging time's dependence on the residence time (τ) and particle volume fraction (?) discovered commercial tubing to be inadequate for the decoupling of the kinetics. The results prescribe why fabricated microreactors with on-chip analytics, particle formations and dissolutions, and without fluidic connections are solutions to discover and develop ubiquitous reactions that form inorganic salt by-products.","author":[{"dropping-particle":"","family":"Chen","given":"Yizheng","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sabio","given":"Jasmine C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Flow Chemistry","id":"ITEM-8","issue":"3","issued":{"date-parts":[["2015"]]},"note":"Liquid-solid clogging prevention","page":"166-171","title":"When Solids Stop Flow Chemistry in Commercial Tubing","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-9","itemData":{"DOI":"10.1021/acs.iecr.5b04813","ISSN":"15205045","abstract":"The direct synthesis of adipic acid from hydrogen peroxide and cyclohexene was investigated in capillary microreactors at high temperature (up to 115 °C) and pressure (up to 70 bar). High temperature was already applied in microflow packed-bed reactors for the direct adipic acid synthesis. In our previous work we showed that the process suffered from unavoidable gas generation due to hydrogen peroxide decomposition when working at low pressure. Herein, we used a high pressure strategy to minimize hydrogen peroxide decomposition. Huge hotspots were observed inside a microflow packed-bed reactor under high pressure conditions. Capillary microreactors display a better heat transfer efficiency and thus may provide a better alternative for scaling-up. Consequently, capillary microreactors were selected for the reaction process with high pressure. One assisting element is the addition of phosphoric acid which is generally known to reduce the decomposition of H2O2. The use of phosphoric acid had a positive influence on the isolated yield. We could improve the yield further by increased interfacial mass transfer between the organic and aqueous slugs, when increasing the flow rate while keeping the same residence time. A further gain was given by using the of 2-stage temperature ramping strategy which we recently introduced for the microflow packed bed reactor. Applying all these aspects led to a maximum yield of 59% at 70-115 °C and 70 bar. The stabilizing effect of phosphoric acid on H2O2 is more obvious in a the 2-stage temperature ramping scenario as in a singleerature operation. In addition, channel clogging by adipic acid precipitation in the microreactor was observed. Therefore, several useful strategies were proposed to prevent channel clogging at high temperature and pressure.","author":[{"dropping-particle":"","family":"Shang","given":"Minjing","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Su","given":"Yuanhai","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hessel","given":"Volker","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Industrial and Engineering Chemistry Research","id":"ITEM-9","issue":"10","issued":{"date-parts":[["2016"]]},"note":"Liquid-Solid, prevention of clogging","page":"2669-2676","title":"High Pressure Direct Synthesis of Adipic Acid from Cyclohexene and Hydrogen Peroxide via Capillary Microreactors","type":"article-journal","volume":"55"},"uris":[""]}],"mendeley":{"formattedCitation":"[15,19,43,45,49,136–139]","plainTextFormattedCitation":"[15,19,43,45,49,136–139]","previouslyFormattedCitation":"[15,19,43,45,49,136–139]"},"properties":{"noteIndex":0},"schema":""}[15,19,43,45,49,136–139]. Reports show that not only are reactors able to operate for significantly longer times without clogging or fouling, but smaller particles can be obtained with narrower size distributions along with increased reaction rates ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-2","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[45,49,93]","plainTextFormattedCitation":"[45,49,93]","previouslyFormattedCitation":"[45,49,93]"},"properties":{"noteIndex":0},"schema":""}[45,49,93]. The mechanisms behind increased mixing have been discussed already in section 2.1 and differ little to none with the presence of solid particles, however the influence of these mechanisms on the solid particles themselves will be discussed in this subsection.Though the mechanisms differ, both high and low frequency ultrasound have proven successful in reducing particle size and help prevent clogging. The cavitation effect of low frequency ultrasound has also aided in enhancing process conditions. Yang et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2016.04.020","ISSN":"18732828","abstract":"Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.","author":[{"dropping-particle":"","family":"Yang","given":"Weimin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yang","given":"Huafang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ding","given":"Wenhao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Bing","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Le","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wang","given":"Lixi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yu","given":"Mingxun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qitu","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"106-117","publisher":"Elsevier B.V.","title":"High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method","type":"article-journal","volume":"33"},"uris":[""]}],"mendeley":{"formattedCitation":"[140]","plainTextFormattedCitation":"[140]","previouslyFormattedCitation":"[140]"},"properties":{"noteIndex":0},"schema":""}[140] utilized low frequency ultrasound to synthesize zinc oxide quantum dots with better size control and increased quantum yield up to 64%. Sebastian et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.7b00193","ISSN":"15287505","abstract":"A sequential-addition microfluidic reactor and an ultrasonic integrated microfluidic reactor were designed to produce with high selectivity hybrid Au–Pd dumbbell-like nanostructures (Au–Pd DBNPs), consisting of a palladium segment tipped with gold heads. A single-stage synthesis was not able to synthesize hybrid nanostructures due to the high reactivity of gold. On the other hand, a two-step method was successful by first synthesizing Pd nanorod-like structures and subsequent growing of Au on the tips of those structures by the localized galvanic replacement reaction. The localized deposition of Au onto both tips of palladium rods was achieved by using two different microfluidic approaches: (i) by sequential injection of gold along the reaction channel at 100 °C and a 5 min residence time, and (ii) by ultrasonic radiation at room temperature and a 2 min residence time. The synthesized Au–Pd DBNPs had higher electrocatalytic activity in the ethanol oxidation reaction in alkaline media than the Pd nanorods.","author":[{"dropping-particle":"","family":"Sebastián","given":"Víctor","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"2700-2710","title":"Microfluidic Assisted Synthesis of Hybrid Au-Pd Dumbbell-like Nanostructures: Sequential Addition of Reagents and Ultrasonic Radiation","type":"article-journal","volume":"17"},"uris":[""]}],"mendeley":{"formattedCitation":"[141]","plainTextFormattedCitation":"[141]","previouslyFormattedCitation":"[141]"},"properties":{"noteIndex":0},"schema":""}[141] observed that under influence of low frequency ultrasound, synthesis of gold-palladium dumbbell-like nanostructures could be carried out at milder temperature of 25 C instead of 100 C, also the residence time was reduced from 5 to 2 min and clogging was avoided. It was speculated that the localized high temperature, due to transient acoustic cavitation, proved beneficial at milder reaction conditions. For the case of low frequency ultrasound, not only does acoustic cavitation promote mixing and reduce particle deposition on channel walls, but it also leads to particle and agglomerate breakup. Resulting in smaller particles with narrower size distributions as mentioned in section 3.1 ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]}],"mendeley":{"formattedCitation":"[45,93]","plainTextFormattedCitation":"[45,93]","previouslyFormattedCitation":"[45,93]"},"properties":{"noteIndex":0},"schema":""}[45,93].Similar results can be achieved with high frequency ultrasound. Reactors are able to operate for longer periods of time due to particle focusing to the center of the channel, which also narrows the velocity distribution leading to shorter growth times and a monomodal distribution ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49]. There are reports where high frequency ultrasound has led to a reduction in particle size ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[49,93]","plainTextFormattedCitation":"[49,93]","previouslyFormattedCitation":"[49,93]"},"properties":{"noteIndex":0},"schema":""}[49,93]. Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49] reduced both the average particle size and the distribution with high frequency ultrasound. Here focused particles are prevented from attaching to the channel walls, where they would grow to either clog the channel or detach as agglomerates. However, the high concentration of particles at the nodal plane can lead to particle agglomeration. In an attempt to avoid this, Dong et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[93]","plainTextFormattedCitation":"[93]","previouslyFormattedCitation":"[93]"},"properties":{"noteIndex":0},"schema":""}[93] combined both high and low frequency ultrasound in periodic intervals to successfully reduce the amount of agglomerates from 21% at high frequency ultrasound to 4.5%–6.7% in the reactor effluent, along with a significant reduction in power consumption (50%–-75%) when compared to the continuous application of low frequency ultrasound.Ultrasound assisted crystallization has long been a topic of interest, not only can crystal sizes and clogging be reduced with ultrasound, as in the case for organic and material synthesis, but there is also a reduction in induction time and metastable zone width ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.6b00696","ISBN":"1528-7483","ISSN":"15287505","abstract":"Continuous-flow crystallization of adipic acid in a millichannel chip equipped with a piezoelectric element is presented and investigated experimentally and numerically. A single, straight channel chip (cross section: 2 mm × 5 mm, length: 76 mm) made of glass, which is ultrasonically transparent, was designed and fabricated. The piezoelectric element allows studying the effect of different ultrasound frequencies in the kHz to MHz range. Ultrasound was applied in burst mode to reduce heating; this allowed operating at higher levels of input power. To accurately control the temperature of the fluid, Peltier elements were used to cool the bottom and top surfaces of the chip. Crystallization was performed in isothermal conditions, ensuring that the temperature and in turn the supersaturation were kept uniform along the channel. The effect of ultrasound frequency and sonication time was studied. Crystal size distributions at different operating conditions were obtained by laser diffraction. The distributions w...","author":[{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"4607-4619","title":"Investigation of the Effect of Ultrasound Parameters on Continuous Sonocrystallization in a Millifluidic Device","type":"article-journal","volume":"16"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/j.cej.2019.122221","ISSN":"13858947","abstract":"? 2019 Elsevier B.V. This work is concerned with the effect of ultrasound on mixing and consequently on crystallization in millifluidic channels. An ultrasonic horn with frequency of 20 kHz was placed inside a vessel with a well-defined geometry containing a single capillary tube with internal diameter (I.D.) of 1.55 or 3.2 mm operated with a fluid flow rate between 1 and 17.6 ml/min. This system was employed to produce crystals of adipic acid in the range of 15–35 ?m. The effect of ultrasound on flow patterns, residence time distribution (RTD) and cooling crystallization were investigated experimentally and numerically. Simulations of acoustic and velocity fields inside the millichannel acting as crystallizer allowed characterizing the acoustic streaming generated within it. In the large capillary, especially at small flow rates, acoustic streaming influenced the flow field, inducing vortices and leading to significant changes in RTD. Conversely, in the small capillary, ultrasound affected the flow field and the RTD negligibly, and a laminar velocity profile with straight streamlines was obtained. As a consequence, different crystallization behaviours were observed in the two capillaries; in particular, while the mean crystal size increased with the sonication residence time in the 1.55 mm I.D. capillary, it decreased in the 3.2 mm I.D. capillary. This difference highlights the importance of considering acoustic streaming when designing sonocrystallizers.","author":[{"dropping-particle":"","family":"Valitov","given":"Gleb","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-2","issue":"122221","issued":{"date-parts":[["2020"]]},"page":"1-13","publisher":"Elsevier","title":"Effect of acoustic streaming on continuous flow sonocrystallization in millifluidic channels","type":"article-journal","volume":"379"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2006.12.004","ISSN":"13504177","abstract":"The positive influence of ultrasound (US) on crystallization processes is shown by the dramatic reduction of the induction period, supersaturation conditions and metastable zone width. Manipulation of this influence can be achieved by changing US-related variables such as frequency, intensity, power and even geometrical characteristics of the ultrasonic device (e.g. horn type size). The volume of the sonicated solution and irradiation time are also variables to be optimized in a case-by-case basis as the mechanisms of US action on crystallization remain to be established. Nevertheless, the results obtained so far make foreseeable that crystal size distribution, and even crystal shape, can be 'tailored' by appropriate selection of the sonication conditions. ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Luque de Castro","given":"M. D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Priego-Capote","given":"F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2007"]]},"page":"717-724","title":"Ultrasound-assisted crystallization (sonocrystallization)","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-4","itemData":{"DOI":"10.1016/j.ultsonch.2019.104743","ISSN":"13504177","abstract":"Continuous crystallization is a fast growing application domain in the pharmaceutical industry. Application of ultrasound has been proven to have positive effects like reduction in induction time and Metastable Zone Width (MSZW) in both batch and flow systems. Further understanding of flow-based sonocrystallization is required to achieve industrial level scale up. This work investigates the sonocrystallization of pharmaceutical compounds in a tubular flow crystallizer. Acetyl Salicylic Acid (ASA-Aspirin) is used as a model compound with ethanol and water as solvent and anti-solvent, respectively. Experiments were conducted in silent and sonicated conditions to study the MSZW. Ultrasound made it possible to achieve crystallization within the crystallizer which was not possible in silent conditions, under the tested conditions. Continuous crystallization was achieved at as low as 48 wt% of anti-solvent and crystallization was already seen at a supersaturation of 1.02. In some experiments, temperature rise with ultrasound caused the crystals to re-dissolve within the channels. Better crystallization – no re-dissolution – was achieved by using low ultrasonic power without any loss in the yield. Particle sizes of product crystals were in the range of 4–46 ?m. In conclusion, ultrasound was highly effective in enabling anti-solvent crystallization of a pharmaceutical compound in a tubular flow crystallizer","author":[{"dropping-particle":"","family":"Hussain","given":"M.N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jordens","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"John","given":"J.J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"T.","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-4","issued":{"date-parts":[["2019"]]},"page":"104743","title":"Enhancing pharmaceutical crystallization in a flow crystallizer with ultrasound: Anti-solvent crystallization","type":"article-journal","volume":"59"},"uris":[""]}],"mendeley":{"formattedCitation":"[105,128,137,142]","plainTextFormattedCitation":"[105,128,137,142]","previouslyFormattedCitation":"[105,128,137,142]"},"properties":{"noteIndex":0},"schema":""}[105,128,137,142]. Rossi et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[120]","plainTextFormattedCitation":"[120]","previouslyFormattedCitation":"[120]"},"properties":{"noteIndex":0},"schema":""}[120] observed that, in their droplet-based microfluidic crystallizer, crystal nuclei were generated easier at a lower supersaturation with sonication, compared to silent conditions. Under conditions where primary nucleation would not occur spontaneously, Hussain et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104743","ISSN":"13504177","abstract":"Continuous crystallization is a fast growing application domain in the pharmaceutical industry. Application of ultrasound has been proven to have positive effects like reduction in induction time and Metastable Zone Width (MSZW) in both batch and flow systems. Further understanding of flow-based sonocrystallization is required to achieve industrial level scale up. This work investigates the sonocrystallization of pharmaceutical compounds in a tubular flow crystallizer. Acetyl Salicylic Acid (ASA-Aspirin) is used as a model compound with ethanol and water as solvent and anti-solvent, respectively. Experiments were conducted in silent and sonicated conditions to study the MSZW. Ultrasound made it possible to achieve crystallization within the crystallizer which was not possible in silent conditions, under the tested conditions. Continuous crystallization was achieved at as low as 48 wt% of anti-solvent and crystallization was already seen at a supersaturation of 1.02. In some experiments, temperature rise with ultrasound caused the crystals to re-dissolve within the channels. Better crystallization – no re-dissolution – was achieved by using low ultrasonic power without any loss in the yield. Particle sizes of product crystals were in the range of 4–46 ?m. In conclusion, ultrasound was highly effective in enabling anti-solvent crystallization of a pharmaceutical compound in a tubular flow crystallizer","author":[{"dropping-particle":"","family":"Hussain","given":"M.N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jordens","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"John","given":"J.J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"T.","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"104743","title":"Enhancing pharmaceutical crystallization in a flow crystallizer with ultrasound: Anti-solvent crystallization","type":"article-journal","volume":"59"},"uris":[""]}],"mendeley":{"formattedCitation":"[142]","plainTextFormattedCitation":"[142]","previouslyFormattedCitation":"[142]"},"properties":{"noteIndex":0},"schema":""}[142] showed that sonication can lead to nucleation without the addition of seeding particles. Speculation suggests that a cavitation bubble can either induce nucleation through expansion, which would lead to the evaporation of the surrounding liquid, cooling down a small zone, or reduce the Gibbs free energy enough to form a stable nucleus. Acoustic cavitation can also lead to particle breakup, producing nuclei for secondary nucleation to occur speeding up the crystallization process. Valitov et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.122221","ISSN":"13858947","abstract":"? 2019 Elsevier B.V. This work is concerned with the effect of ultrasound on mixing and consequently on crystallization in millifluidic channels. An ultrasonic horn with frequency of 20 kHz was placed inside a vessel with a well-defined geometry containing a single capillary tube with internal diameter (I.D.) of 1.55 or 3.2 mm operated with a fluid flow rate between 1 and 17.6 ml/min. This system was employed to produce crystals of adipic acid in the range of 15–35 ?m. The effect of ultrasound on flow patterns, residence time distribution (RTD) and cooling crystallization were investigated experimentally and numerically. Simulations of acoustic and velocity fields inside the millichannel acting as crystallizer allowed characterizing the acoustic streaming generated within it. In the large capillary, especially at small flow rates, acoustic streaming influenced the flow field, inducing vortices and leading to significant changes in RTD. Conversely, in the small capillary, ultrasound affected the flow field and the RTD negligibly, and a laminar velocity profile with straight streamlines was obtained. As a consequence, different crystallization behaviours were observed in the two capillaries; in particular, while the mean crystal size increased with the sonication residence time in the 1.55 mm I.D. capillary, it decreased in the 3.2 mm I.D. capillary. This difference highlights the importance of considering acoustic streaming when designing sonocrystallizers.","author":[{"dropping-particle":"","family":"Valitov","given":"Gleb","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"122221","issued":{"date-parts":[["2020"]]},"page":"1-13","publisher":"Elsevier","title":"Effect of acoustic streaming on continuous flow sonocrystallization in millifluidic channels","type":"article-journal","volume":"379"},"uris":[""]}],"mendeley":{"formattedCitation":"[105]","plainTextFormattedCitation":"[105]","previouslyFormattedCitation":"[105]"},"properties":{"noteIndex":0},"schema":""}[105] placed an ultrasonic horn closed to the capillary tube to study the effect of acoustic streaming on sonocrystallization as seen in Figure 6. They observed that an increase in acoustic streaming led to backmixing and lower local supersaturation, which resulted in smaller crystal sizes.Table 2 summarizes the different processes studied in ultrasonic flow reactors. The reported effects of ultrasound on the specific applications are provided, as well as a short description of the reactor, including the reactor category as mentioned in section 3.1, along with the working frequency, applied power/voltage and reactor dimensions. The scale and/or scale up strategy, as described in section 5, is also mentioned.Figure 6. Schematic of the capillary sonocrystallizer setup used by Valitov et al. to study the effect of acoustic streaming on crystallization, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.122221","ISSN":"13858947","abstract":"? 2019 Elsevier B.V. This work is concerned with the effect of ultrasound on mixing and consequently on crystallization in millifluidic channels. An ultrasonic horn with frequency of 20 kHz was placed inside a vessel with a well-defined geometry containing a single capillary tube with internal diameter (I.D.) of 1.55 or 3.2 mm operated with a fluid flow rate between 1 and 17.6 ml/min. This system was employed to produce crystals of adipic acid in the range of 15–35 ?m. The effect of ultrasound on flow patterns, residence time distribution (RTD) and cooling crystallization were investigated experimentally and numerically. Simulations of acoustic and velocity fields inside the millichannel acting as crystallizer allowed characterizing the acoustic streaming generated within it. In the large capillary, especially at small flow rates, acoustic streaming influenced the flow field, inducing vortices and leading to significant changes in RTD. Conversely, in the small capillary, ultrasound affected the flow field and the RTD negligibly, and a laminar velocity profile with straight streamlines was obtained. As a consequence, different crystallization behaviours were observed in the two capillaries; in particular, while the mean crystal size increased with the sonication residence time in the 1.55 mm I.D. capillary, it decreased in the 3.2 mm I.D. capillary. This difference highlights the importance of considering acoustic streaming when designing sonocrystallizers.","author":[{"dropping-particle":"","family":"Valitov","given":"Gleb","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"122221","issued":{"date-parts":[["2020"]]},"page":"1-13","publisher":"Elsevier","title":"Effect of acoustic streaming on continuous flow sonocrystallization in millifluidic channels","type":"article-journal","volume":"379"},"uris":[""]}],"mendeley":{"formattedCitation":"[105]","plainTextFormattedCitation":"[105]","previouslyFormattedCitation":"[105]"},"properties":{"noteIndex":0},"schema":""}[105], copyright Elsevier. The feed solution was pumped through the pre-cooling section to reach supersaturation and underwent sonocrystallization in the sonication section.Table 2. Summary of the different applications and process enhancement in ultrasonic flow reactors.ProcessesUltrasound effect and application Reactor descriptionReactor scaleReferenceLiquid (single phase)Cavitation to improve mixing of dye and waterLangevin-type transducer reactor, direct coupling20 kHz, 10–30 WSilicon microreactor: channel size 1 × 1 mm2, 0.5 × 0.5 mm2 and 0.5 × 0.25 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15493","ISBN":"9783902661548","ISSN":"14746670","PMID":"23641116","abstract":"Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with dif- ferent modes (volume, shape oscillation, and transient collapse). These cavitation phenomena induce intensive convec- tive mixing and reduce the mixing time from 24–32 s to 0.2–1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conven- tional T-type and higher than the Y-type and Caterpillar microreactors. Residence time distribution was also measured by a stimulus-response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound-induced radial mixing, leading to the increasing of Bo number with ultrasound power.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2016"]]},"page":"1404-1418","title":"Mixing and Residence Time Distribution in Ultrasonic Microreactors","type":"article-journal","volume":"63"},"uris":[""]}],"mendeley":{"formattedCitation":"[24]","plainTextFormattedCitation":"[24]","previouslyFormattedCitation":"[24]"},"properties":{"noteIndex":0},"schema":""}[24]Cavitation to improve mixing of glycerol and waterPiezoelectric plate reactor38.9 kHz, 160 VppPDMS microreactor: channel size 0.24 × 0.15 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/ac5007798","ISSN":"15206882","abstract":"During the deep reactive ion etching process, the sidewalls of a silicon mold feature rough wavy structures, which can be transferredontoapolydimethylsiloxane (PDMS) microchannel through the soft lithography technique. In this article, we utilized the wavy structures ofPDMS microchannel sidewalls to initiate and cavitate bubbles in the presence of acoustic waves. Through bubble cavitation, this acoustofluidic approach demonstrates fast, effective mixing in microfluidics. We characterized its performance by using viscous fluids such as poly(ethylene glycol) (PEG). When two PEG solutions with a resultant viscosity 54.9 times higher than that of water were used, the mixing efficiency was found to be 0.92, indicating excellent, homogeneous mixing. The acoustofluidic micromixer presented here has the advantages of simple fabrication, easy integration, and capability to mix high-viscosity fluids (Reynolds number: ～0.01) in less than 100 ms.","author":[{"dropping-particle":"","family":"Ozcelik","given":"Adem","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ahmed","given":"Daniel","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Xie","given":"Yuliang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nama","given":"Nitesh","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Qu","given":"Zhiguo","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ahsan Nawaz","given":"Ahmad","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Analytical Chemistry","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"page":"5083-5088","publisher":"Americal Chemical Society","title":"An Acousto?uidic Micromixer via Bubble Inception and Cavitation from Microchannel Sidewalls","type":"article-journal","volume":"86"},"uris":[""]}],"mendeley":{"formattedCitation":"[75]","plainTextFormattedCitation":"[75]","previouslyFormattedCitation":"[75]"},"properties":{"noteIndex":0},"schema":""}[75]Ultrasound assisted nitration of tolueneLangevin-type transducer reactor, hybrid contact 21 kHz, 50 WStainless steel capillary: inner diameter 0.6–1 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.05.157","ISSN":"13858947","abstract":"Experimental studies on acoustic cavitation and ultrasound-assisted nitration reaction were systematically investigated in two laboratory-built ultrasonic microreactors by tuning the microchannel dimension, solvent properties and temperature. Under ultrasound irradiation, acoustic cavitation microbubbles were generated and underwent violent oscillation in microchannel. With the decrease of channel size, acoustic cavitation was largely confined, and channel size 1 × 1 mm2 was recognized as the critical size to eliminate the confinement effect. Acoustic cavitation was also highly dependent on the properties of sonicated liquids. The onset of surface wave oscillation on gas bubble was obviously promoted with decreasing solvent viscosity and surface tension. Additionally, ultrasound-assisted nitration process of toluene was studied in a temperature-controlled ultrasonic microreactor. The effects of channel size as well as liquid properties on ultrasound intensification agreed well with the finding in cavitation research. Under ultrasound power 50 W, toluene conversion was enhanced by 9.9%–36.3% utilizing 50 vol.% ethylene glycol aqueous solution as ultrasound propagation medium, exhibiting ultrasound applicability on intensifying fast reaction processes in microreactors.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qiang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"April","issued":{"date-parts":[["2019"]]},"page":"68-78","publisher":"Elsevier","title":"Acoustic cavitation and ultrasound-assisted nitration process in ultrasonic microreactors: The effects of channel dimension, solvent properties and temperature","type":"article-journal","volume":"374"},"uris":[""]}],"mendeley":{"formattedCitation":"[67]","plainTextFormattedCitation":"[67]","previouslyFormattedCitation":"[67]"},"properties":{"noteIndex":0},"schema":""}[67]Gas/liquidCavitation and surface wave oscillation to improve gas-liquid mass transfer for carbon dioxide absorptionLangevin-type transducer reactor, direct coupling20 kHz, 10–50 WSilicon microreactor: channel size 1 × 1 mm2, 0.5 × 0.5 mm2 and 0.5 × 0.25 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.15091","ISBN":"1220-0522","ISSN":"20668279","PMID":"26743299","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Yuchao","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE","id":"ITEM-1","issue":"62","issued":{"date-parts":[["2016"]]},"page":"1294-1307","title":"Hydrodynamics and Mass Transfer of Oscillating Gas-Liquid Flow in Ultrasonic Microreactors","type":"article-journal"},"uris":[""]}],"mendeley":{"formattedCitation":"[38]","plainTextFormattedCitation":"[38]","previouslyFormattedCitation":"[38]"},"properties":{"noteIndex":0},"schema":""}[38]Gas/liquid/solidSonication to partially fluidize a micro-packed-bed reactor to reduce gas-channeling Langevin-type transducer reactor, direct coupling38 kHz, 20 WMicropacked-bed reactor: inner diameter 3.175 mm, diameter of packed beads 0.2 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.iecr.7b03876","ISSN":"15205045","abstract":"Channeling of gas can reduce mass transfer performance in multiphase micropacked-bed reactors. Viscous and capillary forces cause this undesired and often unpredictable phenomenon in systems with catalyst particle sizes of hundreds of micrometers. In this work, we acoustically modify flow in a micropacked-bed reactor to reduce gas channeling by applying high-power sonication at low ultrasonic frequencies (～40 kHz). Experimental residence time distributions reveal two orders of magnitude reduction in dispersion with ultrasound, allowing for nearly plug-flow behavior at high flow rates in the bed. Sonication appears to partially fluidize the packed-bed under pressurized cocurrent two-phase flow, effectively improving dispersion characteristics.","author":[{"dropping-particle":"","family":"Navarro-Brull","given":"Francisco J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"Andrew R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Jisong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gómez","given":"Roberto","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Industrial and Engineering Chemistry Research","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"122-128","title":"Reduction of Dispersion in Ultrasonically-Enhanced Micropacked Beds","type":"article-journal","volume":"57"},"uris":[""]}],"mendeley":{"formattedCitation":"[133]","plainTextFormattedCitation":"[133]","previouslyFormattedCitation":"[133]"},"properties":{"noteIndex":0},"schema":""}[133]Liquid/liquidSurface wave oscillation with the introduction of a gas phase to improve liquid-liquid extractionLangevin-type transducer reactor, direct coupling20 kHz, 5–30 WSilicon microreactor: channel size 1 × 1 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ces.2018.04.042","ISSN":"00092509","abstract":"The synergistic effects of gas agitation and ultrasound on mass transfer between immiscible liquids were investigated in an in-house made ultrasonic microreactor. With the introduction of inert gas (N2), a three-phase slug flow with slug bubbles either dispersed in continuous aqueous phase or encapsulated in oil plugs was observed. Under ultrasound irradiation, slug bubbles underwent surface wave oscillation and induced agitation in microchannel. In addition, microbubbles were generated by acoustic cavitation, oscillating intensely and resulting in the formation of O/W emulsion. Bubble oscillation (i.e., slug bubbles and microbubbles) as well as emulsification promoted liquid-liquid mass transfer significantly. Extraction of vanillin from aqueous solution to toluene was employed to demonstrate the mass transfer enhancement. Compared with silent operation, both mass transfer coefficient and extraction efficiency were largely improved by the combined use of gas agitation and ultrasound. With gas flow velocity being 0.005–0.083 m/s at fixed ultrasound power of 30 W, the overall mass transfer coefficients ranged from 0.047 s?1 to 0.429 s?1, which was 2.33–17.20 times larger than the corresponding liquid-liquid two-phase process without ultrasound irradiation.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yao","given":"Chaoqun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Yanyan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Science","id":"ITEM-1","issued":{"date-parts":[["2018"]]},"page":"122-134","publisher":"Elsevier Ltd","title":"Intensification of liquid-liquid two-phase mass transfer by oscillating bubbles in ultrasonic microreactor","type":"article-journal","volume":"186"},"uris":[""]}],"mendeley":{"formattedCitation":"[39]","plainTextFormattedCitation":"[39]","previouslyFormattedCitation":"[39]"},"properties":{"noteIndex":0},"schema":""}[39]piezoelectric plate reactor1–100 kHz, 10–20 VppPDMS microreactor: channel size 0.2 × 0.05 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1038/srep12572","ISSN":"20452322","abstract":"We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process.","author":[{"dropping-particle":"","family":"Xie","given":"Yuliang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chindam","given":"Chandraprakash","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Nama","given":"Nitesh","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yang","given":"Shikuan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lu","given":"Mengqian","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Yanhui","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mai","given":"John D.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Costanzo","given":"Francesco","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jun Huang","given":"Tony","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Scientific Reports","id":"ITEM-1","issue":"12572","issued":{"date-parts":[["2015"]]},"page":"1-9","publisher":"Nature Publishing Group","title":"Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[130]","plainTextFormattedCitation":"[130]","previouslyFormattedCitation":"[130]"},"properties":{"noteIndex":0},"schema":""}[130]Ultrasound assisted reactive extraction of p-nitrophenylacetateLangevin-type transducer reactor, direct contact 20.3 kHz, 20-29 WPFA Capillary: inner diameter 0.8 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cep.2016.01.003","ISSN":"02552701","abstract":"A new method to apply ultrasound to a microchannel for liquid-liquid extraction was explored. The microchannel tubes are subjected to the ultrasound by direct contact with the transducer without the presence of a liquid medium. The design was constructed with the objectives of reproducibility, proper control of the ultrasound parameters and visibility of the behaviour of the two phase flow under the influence of ultrasound throughout the length of the channel. Two mechanisms of emulsion formation were observed. The effectiveness of the system under the influence of various operating and design parameters was quantified by calculating the yields of the two phase hydrolysis reaction of p-nitrophenyl acetate. The behaviour under various frequencies and amplitude was explored. At a frequency of 20.3. kHz, amplitude of 840. mV and flow rate of 0.1. ml/min the highest increase in yield was observed, which was almost 2.5 times that of the silent condition. A comparison was also made against silent batch and flow conditions to determine the actual effectiveness of the system. To obtain an identical yield of 75% the required residence time could be reduced by a factor of 20 in the sonicated flow condition compared to the silent batch condition.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering and Processing: Process Intensification","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"37-46","publisher":"Elsevier B.V.","title":"Ultrasound assisted liquid-liquid extraction in microchannels-A direct contact method","type":"article-journal","volume":"102"},"uris":[""]}],"mendeley":{"formattedCitation":"[108]","plainTextFormattedCitation":"[108]","previouslyFormattedCitation":"[108]"},"properties":{"noteIndex":0},"schema":""}[108]Langevin-type transducer reactor, hybrid contact 20–65 kHz, 20 WPFA Capillary: inner diameter 0.8–2 mmScale up strategy: scale outADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115]Cavitation to emulsify and improve mixing for the extraction of rhodamine B from water to 1-octanolLangevin-type transducer reactor, direct coupling20 kHz, 10–30 WSilicon microreactor: channel size 1 × 1 mm2 and 0.5 × 0.5 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/aic.16010","abstract":"The effects of ultrasound on the hydrodynamic and mass transfer behaviors of immiscible liquid–liquid two-phase flow was investigated in a domestic ultrasonic microreactor. Under ultrasonic irradiation, cavitation bubble was generated and underwent violent oscillation. Emulsification of immiscible phases was initiated by virtue of oscillating bubbles shuttling through the water/oil interface. The pressure drop was found to decrease with increasing ultrasound power, with a maximum decrement ratio of 12% obtained at power 30 W. The mass transfer behavior was characterized by extraction of Rhodamine B from water to 1-octanol. An enhancement factor of 1.3–2.2 on the overall mass-transfer coef- ficient was achieved under sonication. The mass transfer performance was comparable to passive microreactor at simi- lar energy dissipation rate (61–184 W/kg). The extraction equilibrium was reached under a total flow velocity 0.01 m/s and input power 20 and 30 W, exhibiting its potential use in liquid-liquid extraction process.","author":[{"dropping-particle":"","family":"Zhao","given":"Shuainan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chaoqun","given":"Yao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wen","given":"Zhenghui","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Chen","given":"Guangwen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yuan","given":"Quan","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"AIChE Journal","id":"ITEM-1","issue":"4","issued":{"date-parts":[["2018"]]},"page":"1412-1423","publisher":"AIChE Journal. 64","title":"Liquid-Liquid Two-Phase Flow in Ultrasonic Microreactors: Cavitation, Emulsification and Mass Transfer Enhancement","type":"article-journal","volume":"64"},"uris":[""]}],"mendeley":{"formattedCitation":"[134]","plainTextFormattedCitation":"[134]","previouslyFormattedCitation":"[134]"},"properties":{"noteIndex":0},"schema":""}[134]Ultrasound for oil-water emulsion and PLGA nanoparticle synthesisLangevin-type transducer reactor, indirect coupling24 kHz, 17–32 WGlass tube: inner diameter 2 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2004.10.004","ISSN":"13504177","abstract":"A novel concept was developed here for the continuous, contact- and contamination-free treatment of fluid mixtures with ultrasound. It is based on exciting a steel jacket with an ultrasonic transducer, which transmitted the sound waves via pressurised water to a glass tube installed inside the jacket. Thus, no metallic particles can be emitted into the sonicated fluid, which is a common problem when a sonotrode and a fluid are in direct contact. Moreover, contamination of the fluid from the environment can be avoided, making the novel ultrasonic flow-through cell highly suitable for aseptic production of pharmaceutical preparations. As a model system, vegetable oil-in-water emulsions, fed into the cell as coarse pre-emulsions, were studied. The mean droplet diameter was decreased by two orders of magnitude yielding Sauter diameters of 0.5 μm and below with good repeatability. Increasing the residence time in the ultrasonic field and the sonication power both decreased the emulsion mean diameter. Furthermore, the ultrasonic flow-through cell was found to be well suited for the production of nanoparticles of biodegradable polymers by the emulsion-solvent extraction/ evaporation method. Here, perfectly spherical particles of a volume mean diameter of less than 0.5 μm could be prepared. In conclusion, this novel technology offers a pharmaceutically interesting platform for nanodroplet and nanoparticle production and is well suited for aseptic continuous processing. ? 2004 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Freitas","given":"Sergio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hielscher","given":"Gerhard","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Merkle","given":"Hans P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gander","given":"Bruno","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2006"]]},"page":"76-85","title":"Continuous contact- and contamination-free ultrasonic emulsification - A useful tool for pharmaceutical development and production","type":"article-journal","volume":"13"},"uris":[""]}],"mendeley":{"formattedCitation":"[98]","plainTextFormattedCitation":"[98]","previouslyFormattedCitation":"[98]"},"properties":{"noteIndex":0},"schema":""}[98]Cavitation to enhance emulsification of hexadecane in SDS aqueous emulsionUltrasonic bath reactor37 and 80 kHz, around 180 WCavitation intensification bag: plastic bag with pitsLaboratory and large scaleScale up strategy: numbering upADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2016.12.004","ISSN":"18732828","abstract":"Cavitation Intensifying Bags (CIBs), a novel reactor type for use with ultrasound, have been recently proposed as a scaled-up microreactor with increased energy efficiencies. We now report on the use of the CIBs for the preparation of emulsions out of hexadecane and an SDS aqueous solution. The CIBs have been designed in such a way that cavitation effects created by the ultrasound are increased. It was found that the CIBs were 60 times more effective in breaking up droplets than conventional bags, therewith showing a proof of principle for the CIBs for the preparation of emulsions. Droplets of 0.2 μm could easily be obtained. To our knowledge, no other technology results in the same droplet size more easily in terms of energy usage. Without depending on the wettability changes of the membrane, the CIBs score similarly as membrane emulsification, which is the most energy friendly emulsification method known in literature. Out of the frequencies used, 37 kHz was found to require the lowest treatment time. The treatment time decreased at higher temperatures. While the energy usage in the current non-optimised experiments was on the order of 107-109J/m3, which is comparable to that of a high-pressure homogenizer, we expect that the use of CIBs for the preparation of fine emulsions can still be improved considerably. The process presented can be applied for other uses such as water treatment, synthesis of nanomaterials and food processing.","author":[{"dropping-particle":"","family":"Zwieten","given":"Ralph","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schro?n","given":"Karin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernández Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"446-453","publisher":"Elsevier B.V.","title":"Emulsification in novel ultrasonic cavitation intensifying bag reactors","type":"article-journal","volume":"36"},"uris":[""]}],"mendeley":{"formattedCitation":"[143]","plainTextFormattedCitation":"[143]","previouslyFormattedCitation":"[143]"},"properties":{"noteIndex":0},"schema":""}[143]ProcessesUltrasound effect and application Reactor descriptionReactor scaleReferenceLiquid/solidMaterial synthesisCavitation leading to milder reaction conditions applied to Dumbbell shaped Au-Pd nanoparticle synthesisPiezoelectric plate reactor40 kHz, 30 WSilicon microreactor: square channel 0.4 × 0.4 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.7b00193","ISSN":"15287505","abstract":"A sequential-addition microfluidic reactor and an ultrasonic integrated microfluidic reactor were designed to produce with high selectivity hybrid Au–Pd dumbbell-like nanostructures (Au–Pd DBNPs), consisting of a palladium segment tipped with gold heads. A single-stage synthesis was not able to synthesize hybrid nanostructures due to the high reactivity of gold. On the other hand, a two-step method was successful by first synthesizing Pd nanorod-like structures and subsequent growing of Au on the tips of those structures by the localized galvanic replacement reaction. The localized deposition of Au onto both tips of palladium rods was achieved by using two different microfluidic approaches: (i) by sequential injection of gold along the reaction channel at 100 °C and a 5 min residence time, and (ii) by ultrasonic radiation at room temperature and a 2 min residence time. The synthesized Au–Pd DBNPs had higher electrocatalytic activity in the ethanol oxidation reaction in alkaline media than the Pd nanorods.","author":[{"dropping-particle":"","family":"Sebastián","given":"Víctor","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"2700-2710","title":"Microfluidic Assisted Synthesis of Hybrid Au-Pd Dumbbell-like Nanostructures: Sequential Addition of Reagents and Ultrasonic Radiation","type":"article-journal","volume":"17"},"uris":[""]}],"mendeley":{"formattedCitation":"[141]","plainTextFormattedCitation":"[141]","previouslyFormattedCitation":"[141]"},"properties":{"noteIndex":0},"schema":""}[141]Cavitation to prevent of clogging for AgCl nanoparticle synthesisUltrasonic bath reactor40 kHz, power not mentionedPTFE Tube: inner diameter 1 and 2 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1252/jcej.10we106","ISSN":"00219592","abstract":"We have developed a microreactor system for the continuous producing of nanoparticles, and we have clarified the relationship between the mixing performance of reactors and the particle size. First, we evaluated the mixing performance of reactors by carrying out the Villermaux-Dushman reaction and detd. the exptl. conditions for producing AgCl nanoparticles. Next, we developed the microreactor system by including a pressure sensor and an ultrasonic generator in order to prevent the clogging of nanoparticles. Finally, we produced AgCl nanoparticles and evaluated the mixing performance and the particle size. The operating time of the new system was long. Moreover, we found that as the mixing performance improves the size of produced particles decreases and the particle size distribution becomes sharper. We produced AgCl nanoparticles with a size of 86 nm using the microreactor that had the best mixing performance among the three reactors we tested in this study; the coeff. of variation (Cv) of the size distribution of the produced nanoparticles was 26.1%. [on SciFinder(R)]","author":[{"dropping-particle":"","family":"Katayama","given":"Erika","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Togashi","given":"Shigenori","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Endo","given":"Yoshishige","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Chemical Engineering of Japan","id":"ITEM-1","issue":"12","issued":{"date-parts":[["2010"]]},"page":"1023-1028","title":"Production of AgCl nanoparticles using microreactors","type":"article-journal","volume":"43"},"uris":[""]}],"mendeley":{"formattedCitation":"[144]","plainTextFormattedCitation":"[144]","previouslyFormattedCitation":"[144]"},"properties":{"noteIndex":0},"schema":""}[144]Cavitation to change structure of ZnO quantum dots due to high energy hotspotsUltrasonic bath reactor53 kHz, 72–180 WPTFE Tube: inner diameter 0.8 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2016.04.020","ISSN":"18732828","abstract":"Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.","author":[{"dropping-particle":"","family":"Yang","given":"Weimin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yang","given":"Huafang","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ding","given":"Wenhao","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Bing","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Le","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wang","given":"Lixi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yu","given":"Mingxun","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhang","given":"Qitu","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"106-117","publisher":"Elsevier B.V.","title":"High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method","type":"article-journal","volume":"33"},"uris":[""]}],"mendeley":{"formattedCitation":"[140]","plainTextFormattedCitation":"[140]","previouslyFormattedCitation":"[140]"},"properties":{"noteIndex":0},"schema":""}[140]Cavitation to promote uniform particle shape and size, improved crystal quality applied to precipitation of hydroxyapatite.Reactor type 1: ultrasonic bath reactor40 kHz, 4–8 WTeflon Tube: inner diameter 1.02 mmReactor type 2: piezoelectric plate reactor 50 kHz, 30 WTeflon microreactor: channel width 0.6 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2012.11.014","ISSN":"13858947","abstract":"This paper describes the continuous-flow precipitation of hydroxyapatite Ca5(PO4)3OH (HAp) in two ultrasonic microreactors using diluted aqueous solutions of calcium and phosphate at 37°C. Precipitation of HAp was first carried out in a tubular microreactor immersed in an ultrasonic bath, where single-phase (laminar) flow and segmented gas-liquid flow were both evaluated. The single-phase flow study was then conducted in a novel microfluidic device developed at MIT. It consists of a Teflon stack microreactor with an integrated piezoelectric element (Teflon microreactor), thereby allowing the direct transmission of ultrasound to the reactor. Both microsystems produce single-phased calcium-deficient carbonated HAp under near-physiological conditions of temperature and pH. In addition, particle aggregation and primary particle size were significantly reduced in the segmented-flow tubular microreactor and in the Teflon microreactor. The as-prepared particles mostly consisted of rod-like shape nanoparticles with dimensions below 100nm in length and around 20nm in width. Further, the microreactors used yielded HAp particles with improved characteristics, namely higher crystallinity and less carbonate contamination, when compared to the HAp particles produced in a stirred tank batch reactor. ? 2012 Elsevier B.V.","author":[{"dropping-particle":"","family":"Castro","given":"Filipa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ferreira","given":"António","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rocha","given":"Fernando","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Vicente","given":"António","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"José António","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issued":{"date-parts":[["2013"]]},"page":"979-987","publisher":"Elsevier B.V.","title":"Continuous-flow precipitation of hydroxyapatite in ultrasonic microsystems","type":"article-journal","volume":"215-216"},"uris":[""]}],"mendeley":{"formattedCitation":"[44]","plainTextFormattedCitation":"[44]","previouslyFormattedCitation":"[44]"},"properties":{"noteIndex":0},"schema":""}[44]Cavitation for clogging prevention, particle size control applied to barium sulfate precipitationLangevin-type transducer reactor, direct coupling21–46 kHz, 11–23 WSilicon microreactor: square channel 0.6 × 0.6 mm?Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.03.012","ISSN":"18732828","abstract":"Ultrasonic micro-reactors are frequently applied to prevent micro-channel clogging in the presence of solid materials. Continuous sonication will lead to a sizeable energy input resulting in a temperature increase in the fluidic channels and concerns regarding microchannel degradation. In this paper, we investigate the application of pulsed ultrasound as a less invasive approach to prevent micro-channel clogging, while also controlling the temperature increase. The inorganic precipitation of barium sulfate particles was studied, and the impact of the effective ultrasonic treatment ratio, frequency and load power on the particle size distribution, pressure and temperature was quantified in comparison to non-sonicated experiments. The precipitation reactions were performed in a continuous reactor consisting of a micro-reactor chip attached to a Langevin-type transducer. It was found that adjusting the pulsed ultrasound conditions prevented microchannel clogging by reducing the particle size to the same magnitude as observed for continuous sonication. Furthermore, reducing the effective treatment ratio from 100 to 12.5% decreases the temperature rise from 7 to 1 °C.","author":[{"dropping-particle":"","family":"Delacour","given":"Claire","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lutz","given":"Cecile","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"67-74","publisher":"Elsevier","title":"Pulsed ultrasound for temperature control and clogging prevention in micro-reactors","type":"article-journal","volume":"55"},"uris":[""]}],"mendeley":{"formattedCitation":"[45]","plainTextFormattedCitation":"[45]","previouslyFormattedCitation":"[45]"},"properties":{"noteIndex":0},"schema":""}[45]Acoustophoresis for clogging prevention, particle size control applied to particle synthesisPiezoelectric plate reactor1.21 MHz, 0.3–3.3 WSilicon microreactor: square channel 0.6 × 0.6 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/C8LC00675J","ISSN":"14730189","abstract":"An acoustophoretic microreactor to manage particles in flow and to control the material synthesis process.The handling of solids in microreactors represents a challenging task. In this paper, we present an acoustophoretic microreactor developed to manage particles in flow and to control the material synthesis process. The reactor was designed as a layered resonator with an actuation frequency of 1.21 MHz, in which a standing acoustic wave is generated in both the depth and width direction of the microchannel. The acoustophoretic force exerted by the standing wave on the particles focuses them to the channel center. A parametric study of the effect of flow rate, particle size and ultrasound conditions on the focusing efficiency was performed. Furthermore, the reactive precipitation of calcium carbonate and barium sulfate was chosen as a model system for material synthesis. The acoustophoretic focusing effect avoids solid deposition on the channel walls and thereby minimizes reactor fouling and thus prevents clogging. Both the average particle size and the span of the particle size distribution of the synthesized particles are reduced by applying high-frequency ultrasound. The developed reactor has the potential to control a wide range of material synthesis processes.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"316-327","publisher":"Royal Society of Chemistry","title":"Acoustophoretic focusing effects on particle synthesis and clogging in microreactors","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[49]","plainTextFormattedCitation":"[49]","previouslyFormattedCitation":"[49]"},"properties":{"noteIndex":0},"schema":""}[49]Combining cavitation and acoustophoresis for particle synthesisPiezoelectric plate reactor61.7 kHz (8 W) and 1.21 MHz (1.6 W), pulse and switch mode: power = 2–8 WSilicon microreactor: square channel 0.6 × 0.6 mm2Laboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104800","ISSN":"1350-4177","abstract":"Ultrasound (US) is a promising method to address clogging and mixing issues in microreactors (MR). So far, low frequency US (LFUS), pulsed LFUS and high frequency US (HFUS) have been used independently in MR for particle synthesis to achieve narrow particle size distributions (PSD). In this work, we critically assess the ad- vantages and disadvantages of each US application method for the case study of calcium carbonate synthesis in an ultrasonic microreactor (USMR) setup operating at both LFUS (61.7 kHz, 8 W) and HFUS (1.24 MHz, 1.6 W). Furthermore, we have developed a novel approach to switch between LFUS and HFUS in an alternating manner, allowing us to quantify the synergistic effect of performing particle synthesis under two different US conditions. The reactor was fabricated by gluing a piezoelectric plate transducer to a silicon microfluidic chip. The results show that independently applying HFUS and LFUS produces a narrower PSD compared to silent conditions. However, at lower flow rates HFUS leads to agglomerate formation, while the reaction conversion is not en- hanced due to weak mixing effects. LFUS on the other hand eliminates particle agglomerates and increases the conversion due to the strong cavitation effect. However, the required larger power input leads to a steep tem- perature rise in the reactor and the risk of reactor damage for long-term operation. While pulsed LFUS reduces the temperature rise, this application mode leads again to the formation of particle agglomerates, especially at low LFUS percentage. The proposed application mode of switching between LFUS and HFUS is proven to combine the advantages of both LFUS and HFUS, and results in particles with a unimodal narrow PSD (one order of magnitude reduction in the average size and span compared to silent conditions) and negligible rise of the reactor temperature. 1.","author":[{"dropping-particle":"","family":"Dong","given":"Zhengya","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Udepurkar","given":"Aniket Pradip","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics - Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2020"]]},"page":"104800","publisher":"Elsevier","title":"Synergistic effects of the alternating application of low and high frequency ultrasound for particle synthesis in microreactors","type":"article-journal","volume":"60"},"uris":[""]}],"mendeley":{"formattedCitation":"[93]","plainTextFormattedCitation":"[93]","previouslyFormattedCitation":"[93]"},"properties":{"noteIndex":0},"schema":""}[93]Liquid/solidOrganic synthesisCavitation for clogging prevention applied to C–-N cross coupling reactionUltrasonic bath reactor41.5 kHz, power not mentionedPFA tube: inner diameter 1.01 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c0sc00524j","ISSN":"20416520","abstract":"A continuous-flow palladium-catalyzed animation reaction was made possible through efficient handling of solids via acoustic irradiation. Various diarylamines were obtained with reaction times ranging from 20 s to 10 min. ? The Royal Society of Chemistry 2011.","author":[{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mcmullen","given":"Jonathan P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Science","id":"ITEM-1","issue":"2","issued":{"date-parts":[["2011"]]},"page":"287-290","title":"Palladium-catalyzed amination reactions in flow: Overcoming the challenges of clogging via acoustic irradiation","type":"article-journal","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[113]","plainTextFormattedCitation":"[113]","previouslyFormattedCitation":"[113]"},"properties":{"noteIndex":0},"schema":""}[113]Ultrasonic bath reactor41.5 kHz, power not mentionedPFA tube: inner diameter 0.5 and 1 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/op100154d","ISSN":"10836160","abstract":"We investigate the mechanisms that govern plugging in microreactors during Pd-catalyzed amination reactions. Both bridging and constriction were shown to be important mechanisms that lead to clogging in our system and greatly limited the utility of microsystems for this class of reactions. On the basis of these observations, several approaches were engineered to overcome the challenge of plugging and to enable the continuous-flow synthesis of a biarylamine. Bridging could be eliminated with acoustic irradiation while constriction was managed via fluid velocity and the prediction of growth rates. ? 2010 American Chemical Society.","author":[{"dropping-particle":"","family":"Hartman","given":"Ryan L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Naber","given":"John R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zaborenko","given":"Nikolay","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Buchwald","given":"Stephen L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-1","issued":{"date-parts":[["2010"]]},"page":"1347-1357","title":"Overcoming the challenges of solid bridging and constriction during Pd-catalyzed C-N bond formation in microreactors","type":"article-journal","volume":"14"},"uris":[""]}],"mendeley":{"formattedCitation":"[15]","plainTextFormattedCitation":"[15]","previouslyFormattedCitation":"[15]"},"properties":{"noteIndex":0},"schema":""}[15]Piezoelectric plate reactor 50 kHz, 30 WTeflon microreactor: channel width 0.6 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c1lc20337a","ISSN":"14730189","abstract":"We present a general inexpensive method for realizing a Teflon stack microreactor with an integrated piezoelectric actuator for conducting chemical synthesis with solid products. The microreactors are demonstrated with palladium-catalyzed C-N cross-coupling reactions, which are prone to clogging microchannels by forming insoluble salts as by-products. Investigations of the ultrasonic waveform applied by the piezoelectric actuator reveal an optimal value of 50 kHz at a load power of 30 W. Operating the system at these conditions, the newly developed Teflon microreactor handles the insoluble solids formed and no clogging is observed. The investigated reactions reach full conversion in very short reaction times and high isolated yields are obtained (>95% yield).","author":[{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"No?l","given":"Timothy","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gu","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Heider","given":"Patrick L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issue":"15","issued":{"date-parts":[["2011"]]},"page":"2488-2492","title":"A Teflon microreactor with integrated piezoelectric actuator to handle solid forming reactions","type":"article-journal","volume":"11"},"uris":[""]}],"mendeley":{"formattedCitation":"[43]","plainTextFormattedCitation":"[43]","previouslyFormattedCitation":"[43]"},"properties":{"noteIndex":0},"schema":""}[43]Cavitation for clogging prevention applied to KMnO4 oxidationUltrasonic bath reactor44 kHz, pulsed (5 s every minute), power not mentionedPFA tube: inner diameter 0.5 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/ol101345z","ISSN":"00404020","abstract":"An efficient and easily scalable transformation of alcohols and aldehydes to carboxylic acids and nitroalkane derivatives to the corresponding carbonyls and carboxylic acids using permanganate as the oxidant within a continuous flow reactor is reported. Notably, the generation and downstream processing of MnO2 slurries was not found to cause any blocking of the reactor when ultrasound pulses were applied to the flow system","author":[{"dropping-particle":"","family":"Sedelmeier","given":"J?rg","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"V.","family":"Ley","given":"Steven","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Baxendale","given":"Ian R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Baumann","given":"Marcus","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic letters","id":"ITEM-1","issue":"16","issued":{"date-parts":[["2010"]]},"page":"3618-3621","title":"KMnO4-Mediated Oxidation as a Continuous Flow Process","type":"article-journal","volume":"12"},"uris":[""]}],"mendeley":{"formattedCitation":"[145]","plainTextFormattedCitation":"[145]","previouslyFormattedCitation":"[145]"},"properties":{"noteIndex":0},"schema":""}[145]Cavitation for clogging prevention applied to photodimerization of maleic anhydrideUltrasonic bath reactor39 kHz, 100 WFEP tube: inner diameter 0.5–1.6 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/op900306z","ISSN":"10836160","abstract":"Photodimerization of maleic anhydride (MA) gives insoluble precipitated products that can be a trigger to clog a conventional microreactor. To avoid this problem, we devised a microreactor that uses liquid/gas slug flow and ultrasonication. Inert N-2 gas introduced into the reaction solution swept through the reactor tube and transported precipitated products in the liquid segnients. Ultrasound vibrations inhibited the adhesion and sedimentation of precipitate in the reactor tube. The combination of gas and ultrasound prevented the tube from clogging. Fluorinated ethylene propylene (FEP) tubes of various sizes were investigated to use as a tube reactor. The tubes were wound around a high-pressure Hg lamp with a Pyrex immersion well which has been using generally as a light source of photoreaction, and the reaction solution was then passed through the tube and irradiated through the tube wall. The slug flow microreactor could be operated for more than 16 h continuously without clogging. Compared to using a batch reactor, this method achieves better product quality, improved conversion, and reduced waste.","author":[{"dropping-particle":"","family":"Horie","given":"Tomoaki","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Sumino","given":"Motoshige","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Tanaka","given":"Takumi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Matsushita","given":"Yoshihisa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ichimura","given":"Teijiro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Yoshida","given":"Jun-Ichi","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-1","issued":{"date-parts":[["2010"]]},"page":"405-410","title":"Photodimerization of maleic anhydride in a microreactor without clogging","type":"article-journal","volume":"14"},"uris":[""]}],"mendeley":{"formattedCitation":"[112]","plainTextFormattedCitation":"[112]","previouslyFormattedCitation":"[112]"},"properties":{"noteIndex":0},"schema":""}[112]Cavitation for clogging prevention applied to arylation of aryl bromidesUltrasonic bath reactor40 kHz, 150 WCapillary coil: inner diameter 0.53 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2011.07.008","ISSN":"18732828","abstract":"An intramolecular direct arylation of various aryl bromides was performed using ultrasonic irradiation and a continuous flow capillary microreactor. The present procedure provided a higher functional group tolerance, ligand-free, milder reaction conditions and a shorter reaction time for the direct arylation compared with the conventional methods. The ultrasonic irritation not only greatly promoted the conversion and selectivity of the direct arylation, but also solved the clogging problem of the microreactor for solid-forming reaction and made the reaction run smoothly. ? 2011 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Zhang","given":"Lei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Geng","given":"Mei","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teng","given":"Peng","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zhao","given":"Dan","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Lu","given":"Xi","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Li","given":"Jian Xin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2012"]]},"page":"250-256","title":"Ultrasound-promoted intramolecular direct arylation in a capillary flow microreactor","type":"article-journal","volume":"19"},"uris":[""]}],"mendeley":{"formattedCitation":"[146]","plainTextFormattedCitation":"[146]","previouslyFormattedCitation":"[146]"},"properties":{"noteIndex":0},"schema":""}[146]Liquid/solidSonocrystallizationEnhanced nucleation with ultrasound for adipic acid crystallizationLangevin-type transducer reactor, indirect coupling20 kHz, 750 W, Amplitude 21%PFA Capillary: inner diameter 1 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.5b01153","ISSN":"15287505","abstract":"A novel design for continuous flow sonocrystallization of adipic acid in a capillary device is presented and investigated experimentally and numerically. The effect of supersaturation and ultrasound power is studied. To elucidate the relationship between crystallization and cavitation, sonochemiluminescence and sonoemulsification experiments are performed, and numerical investigation of the wave propagation in aqueous solution is used to predict the probability of cavitation. Crystal size distribution at different operating conditions is obtained by laser diffraction. Narrow size distributions, small mean size of crystals (ca. 15 μm), and high crystal production rate are achieved when applying ultrasound. In addition, numerical simulations of pressure distribution show that high pressure amplitudes are obtainable near the vicinity of the sonoprobe tip. Using a cavitation threshold formulation, the distance from the tip where transient cavitation takes place is quantified. The results are in agreement with the experimental findings, in which by increasing the distance between capillary and sonoprobe, emulsification, sonochemiluminescence, and nucleation decrease. It is concluded that transient cavitation of bubbles is a significant mechanism for enhancing nucleation of crystals among the several proposed in the literature.","author":[{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2015"]]},"page":"5519-5529","title":"Continuous-Flow Sonocrystallization in Droplet-Based Microfluidics","type":"article-journal","volume":"15"},"uris":[""]}],"mendeley":{"formattedCitation":"[120]","plainTextFormattedCitation":"[120]","previouslyFormattedCitation":"[120]"},"properties":{"noteIndex":0},"schema":""}[120]Enhanced anti-solvent mixing, reduced induction times and anti-solvent crystallization at a lower supersaturation with ultrasound for acetyl salicylic acid crystallizationLangevin-type transducer reactor, hybrid contact 42 kHz, 7–24 WPFA Capillary: inner diameter 2 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2019.104743","ISSN":"13504177","abstract":"Continuous crystallization is a fast growing application domain in the pharmaceutical industry. Application of ultrasound has been proven to have positive effects like reduction in induction time and Metastable Zone Width (MSZW) in both batch and flow systems. Further understanding of flow-based sonocrystallization is required to achieve industrial level scale up. This work investigates the sonocrystallization of pharmaceutical compounds in a tubular flow crystallizer. Acetyl Salicylic Acid (ASA-Aspirin) is used as a model compound with ethanol and water as solvent and anti-solvent, respectively. Experiments were conducted in silent and sonicated conditions to study the MSZW. Ultrasound made it possible to achieve crystallization within the crystallizer which was not possible in silent conditions, under the tested conditions. Continuous crystallization was achieved at as low as 48 wt% of anti-solvent and crystallization was already seen at a supersaturation of 1.02. In some experiments, temperature rise with ultrasound caused the crystals to re-dissolve within the channels. Better crystallization – no re-dissolution – was achieved by using low ultrasonic power without any loss in the yield. Particle sizes of product crystals were in the range of 4–46 ?m. In conclusion, ultrasound was highly effective in enabling anti-solvent crystallization of a pharmaceutical compound in a tubular flow crystallizer","author":[{"dropping-particle":"","family":"Hussain","given":"M.N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jordens","given":"J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"John","given":"J.J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"L.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"T.","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"104743","title":"Enhancing pharmaceutical crystallization in a flow crystallizer with ultrasound: Anti-solvent crystallization","type":"article-journal","volume":"59"},"uris":[""]}],"mendeley":{"formattedCitation":"[142]","plainTextFormattedCitation":"[142]","previouslyFormattedCitation":"[142]"},"properties":{"noteIndex":0},"schema":""}[142]Increased nucleation rate and smaller crystals size with pulsed ultrasound for adipic acid crystallizationPiezoelectric plate reactor 42–1090 kHz, pulsed, 400 mVpp, duty cycle 1%–7%Glass milli-reactor: channel 2 × 5 mm2Scale up strategy: micro to milliscale ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.6b00696","ISBN":"1528-7483","ISSN":"15287505","abstract":"Continuous-flow crystallization of adipic acid in a millichannel chip equipped with a piezoelectric element is presented and investigated experimentally and numerically. A single, straight channel chip (cross section: 2 mm × 5 mm, length: 76 mm) made of glass, which is ultrasonically transparent, was designed and fabricated. The piezoelectric element allows studying the effect of different ultrasound frequencies in the kHz to MHz range. Ultrasound was applied in burst mode to reduce heating; this allowed operating at higher levels of input power. To accurately control the temperature of the fluid, Peltier elements were used to cool the bottom and top surfaces of the chip. Crystallization was performed in isothermal conditions, ensuring that the temperature and in turn the supersaturation were kept uniform along the channel. The effect of ultrasound frequency and sonication time was studied. Crystal size distributions at different operating conditions were obtained by laser diffraction. The distributions w...","author":[{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"4607-4619","title":"Investigation of the Effect of Ultrasound Parameters on Continuous Sonocrystallization in a Millifluidic Device","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[128]","plainTextFormattedCitation":"[128]","previouslyFormattedCitation":"[128]"},"properties":{"noteIndex":0},"schema":""}[128]Backmixing lead to lower yield, smaller crystal size with ultrasoundLangevin-type transducer reactor, indirect coupling20 kHz, 750 W, amplitude 21% FEP Capillary: diameter 1.55 and 3.2 mmLaboratory scaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cej.2019.122221","ISSN":"13858947","abstract":"? 2019 Elsevier B.V. This work is concerned with the effect of ultrasound on mixing and consequently on crystallization in millifluidic channels. An ultrasonic horn with frequency of 20 kHz was placed inside a vessel with a well-defined geometry containing a single capillary tube with internal diameter (I.D.) of 1.55 or 3.2 mm operated with a fluid flow rate between 1 and 17.6 ml/min. This system was employed to produce crystals of adipic acid in the range of 15–35 ?m. The effect of ultrasound on flow patterns, residence time distribution (RTD) and cooling crystallization were investigated experimentally and numerically. Simulations of acoustic and velocity fields inside the millichannel acting as crystallizer allowed characterizing the acoustic streaming generated within it. In the large capillary, especially at small flow rates, acoustic streaming influenced the flow field, inducing vortices and leading to significant changes in RTD. Conversely, in the small capillary, ultrasound affected the flow field and the RTD negligibly, and a laminar velocity profile with straight streamlines was obtained. As a consequence, different crystallization behaviours were observed in the two capillaries; in particular, while the mean crystal size increased with the sonication residence time in the 1.55 mm I.D. capillary, it decreased in the 3.2 mm I.D. capillary. This difference highlights the importance of considering acoustic streaming when designing sonocrystallizers.","author":[{"dropping-particle":"","family":"Valitov","given":"Gleb","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Journal","id":"ITEM-1","issue":"122221","issued":{"date-parts":[["2020"]]},"page":"1-13","publisher":"Elsevier","title":"Effect of acoustic streaming on continuous flow sonocrystallization in millifluidic channels","type":"article-journal","volume":"379"},"uris":[""]}],"mendeley":{"formattedCitation":"[105]","plainTextFormattedCitation":"[105]","previouslyFormattedCitation":"[105]"},"properties":{"noteIndex":0},"schema":""}[105]Cavitation for clogging prevention applied to crystallization processes (Patent)Piezoelectric plate reactorPiezoelectric ring attached to tubing with adaptable diameterScale up strategy: micro to milliscale and parallel numbering-upADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Gallaher","given":"Amanda","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hannon","given":"Dominic","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hardie","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issued":{"date-parts":[["2005"]]},"number":"WO2005/068068","publisher-place":"Great Britain","title":"Improvements in and relating to Sonochemistry","type":"patent"},"uris":[""]}],"mendeley":{"formattedCitation":"[147]","plainTextFormattedCitation":"[147]","previouslyFormattedCitation":"[147]"},"properties":{"noteIndex":0},"schema":""}[147]Langevin-type transducer reactor, direct couplingReactor wrapped as a helix around a sonotrodeScale up strategy: micro to milliscale and parallel numbering upADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"abstract":"AN ultrasound crystallization device comprises a tubular crystallization reactor for conducting process fluid containing substance to be crystallized, an ultrasound source for radiating ultrasound to the tubular crystallization reactor, and a temperature-control structure for controlling the temperature of the process fluid with the aid of temperature-control fluid. The tubular crystallization reactor is shaped to conduct the process fluid to flow aound the ultrasound source, and the temperature-control structure comprises a flow-guide structure for guiding at least a part of the temperature-control fluid to flow around the ultrasound source. The flow-guide structure improves the accuracy of the temperature control of the process fluid and also the ability of the temperature control to react to changes.","author":[{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ekberg","given":"Bjarne","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"H?kkinen","given":"Antti","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Varis","given":"Juha","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Louhi-Kultanen","given":"Marjatta","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issued":{"date-parts":[["2018"]]},"number":"WO2018/096205A1","title":"An ultrasound crystallization device and an ultrasound crystallization system","type":"patent"},"uris":[""]},{"id":"ITEM-2","itemData":{"author":[{"dropping-particle":"","family":"Ezeanowi","given":"Nnaemeka","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"International Process Intensification Conference 2019","id":"ITEM-2","issued":{"date-parts":[["2019"]]},"page":"2-3","title":"Effect of process parameters on a novel modular continuous crystallizer","type":"paper-conference","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[148,149]","plainTextFormattedCitation":"[148,149]","previouslyFormattedCitation":"[148,149]"},"properties":{"noteIndex":0},"schema":""}[148,149]Langevin-type transducer reactor, indirect couplingReactor wrapped as a helix and immersed in a jacketed beaker for temperature control. Ultrasonic transducer attached to the bottom of the beakerScale up strategy: micro to milliscaleADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"abstract":"The invention relates to a method and apparatus for continuous crystallization. According to the invention, starting material is fed to a crystallization unit which comprises at least one crystallization reactor, and the starting material is treated by continuous crystallization in at least one crystallization reactor for forming crystals, and ultrasound is applied in connection with crystallization.","author":[{"dropping-particle":"","family":"Karvonen","given":"Vesa","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"H?kkinen","given":"Antti","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Louhi-Kultanen","given":"Marjatta","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issue":"12","issued":{"date-parts":[["2016"]]},"number":"WO 2016/107968 AI","publisher-place":"Finland","title":"Method and apparatus for continuous crystallization and use thereof","type":"patent"},"uris":[""]}],"mendeley":{"formattedCitation":"[150]","plainTextFormattedCitation":"[150]","previouslyFormattedCitation":"[150]"},"properties":{"noteIndex":0},"schema":""}[150]5. Scale-up of ultrasound reactorsIn the previous parts of this review, the combination of ultrasound and microreactors has been described at a laboratory scale. In this part, the scalability approach of such reactors will be investigated. As for small scale reactors the main challenge is the distribution of acoustic field. The choice of the scalability approach is highly dependent on the expected effect of ultrasound on a specific application.Concerning the scalability of microreactors alone, two main strategies have been developed over the last decade ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1039/c4lc00330f","abstract":"Chemical synthesis in microsystems has evolved from simple proof-of-principle examples to become a general technique in academia and industry. Numerous such \" flow chemistry \" applications are now found in pharmaceutical and fine chemical synthesis. Much of the development has been based on systems employing macroscopic flow components and tubes, rather than the integrated chip technology envisioned by the lab-on-a-chip community. We review the major developments in systems for flow chemistry and discuss limitations underlying the development of chip-scale integrated systems.","author":[{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Reizman","given":"Brandon J.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Newman","given":"Stephen G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Lab on a Chip","id":"ITEM-1","issued":{"date-parts":[["2014"]]},"note":"Applications Pharmaceuticals and fine chemistry \nAdvantages:\n- Controlled mixing\n\n- Enhance heat and mass transfer\n\n- Enable safe operation of highly reactive intermediate, exothermic reactions\n\n- Reducing accumulation of reactive or toxic intermediate \nDrawbacks: Handling of solid\n\n\nHandling of solid: \n- Increase of pressure drop: use of surfaces that do not promote solid nucleation (but periodic flushing is necessary)\n\n- Parallel micro-reactors\n\n- Ultrasound transducer (Org. Process Res. Dev., 2010, 14, 1347-1357; Lab Chip, 2011, 11, 2488-2492; Angew. Chem., Int. Ed., 2011, 50, 5943-5946)\n\n\nBetter control and understanding of nucleation mechanism in continuous flow allow:\n\n- Run of reactions forming solids\n\n- Enable the implementation of nucleation as a purification techniques\n\n- Development of small-scale filtration techniques (dieletriphoresis and centrifugal forces)","page":"3206-3212","title":"Tools for chemical synthesis in microsystems","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1146/annurev-chembioeng- 060816-101443","abstract":"The past two decades have witnessed a rapid development of microreac-tors. A substantial number of reactions have been tested in microchemical systems, revealing the advantages of controlled residence time, enhanced transport efficiency, high product yield, and inherent safety. This review defines the microchemical system and describes its components and appli-cations as well as the basic structures of micromixers. We focus on mixing, flow dynamics, and mass and heat transfer in microreactors along with three strategies for scaling up microreactors: parallel numbering-up, consecutive numbering-up, and scale-out. We also propose a possible methodology to design microchemical systems. Finally, we provide a summary and future prospects.","author":[{"dropping-particle":"","family":"Zhang","given":"Jisong","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Wang","given":"Kai","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Teixeira","given":"Andrew R.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Jensen","given":"Klavs F.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Luo","given":"Guangsheng","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Annu. Rev. Chem. Biomol. Eng","id":"ITEM-2","issued":{"date-parts":[["2017"]]},"page":"13.1-13.21","title":"Design and Scaling Up of Microchemical Systems: A Review","type":"article-journal","volume":"8"},"uris":[""]}],"mendeley":{"formattedCitation":"[151,152]","plainTextFormattedCitation":"[151,152]","previouslyFormattedCitation":"[151,152]"},"properties":{"noteIndex":0},"schema":""}[151,152]. The first method, known as scaling out, consists of increasing the characteristic size of the channels. The second method, numbering up, is achieved by running several identical units in parallel. Both methods are effective to a different extent, which mostly depends on the application and reactor design. Because Since these reactors are able to run continuously, they have an intrinsic advantage when it comes to meeting industrial production demands. Not only do continuous reactors allow for better control of the final product quality, but they are also able to reach higher production rates compared to batch reactors ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/op200347k","ISSN":"10836160","abstract":"Continuous operations have become popular in both academia and the pharmaceutical industry. Continuous operations may be developed to make high-quality material safely, or because continuous operations are the only effective and economical way to make larger quantities of material. This review surveys the area of continuous processes used to make larger quantities of material and discusses the feasibility of developing economical continuous operations. ? 2012 American Chemical Society.","author":[{"dropping-particle":"","family":"Anderson","given":"Neal G.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Organic Process Research and Development","id":"ITEM-1","issue":"5","issued":{"date-parts":[["2012"]]},"page":"852-869","title":"Using continuous processes to increase production","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[153]","plainTextFormattedCitation":"[153]","previouslyFormattedCitation":"[153]"},"properties":{"noteIndex":0},"schema":""}[153]. As mentioned earlier, Table 2 includes the different reactors described in this part and highlights the scale-up strategies.The main parameter limiting the number of applications of ultrasonic milli-reactors at industrial scale is the acoustic pressure field distribution in the liquid medium. Verhaagen et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1002/slct.201600023","abstract":"Bubbles created with ultrasound from artifical microscopic crevices can improve energy efficiency values for the creation of radicals; nevertheless it has been conducted so far only under special laboratory conditions. Limited reproducibility of results and poor energy efficiency are constraints for the sonochemistry and ultrasonics community to scale-up applied chemical processes. For the first time, using conventional ultrasonic bath technology, the numbering-up and scale-up of a microfluidic sonochemical reactor have been achied. Sonochemical effects such as radical production and sonoluminescence were intensified by the modification of the inner walls of a novel Cavitation Intensification Bag. While 25 times bigger than the previous microreactor, a reduction of 22% in standard deviation and an increase of 45.1% in efficiency compared to bags without pits were obtained. Mechanical effects accompanying bubble collapse lead to two distinct types of erosion marks in the bags.\r\n","author":[{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Liu","given":"Youlin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Pérez","given":"Andrés Galdames","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernandez?Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"ChemistrySelect","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"136-139","title":"Scaled-up sonochemical microreactor with increased efficiency and reproducibility","type":"article-journal","volume":"2"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1088/1742-6596/656/1/012112","ISSN":"17426596","abstract":"We introduce a Cavitation Intensifying Bag as a versatile tool for acoustic cavitation control. The cavitation activity is spatially controlled by the modification of the inner surface of the bag with patterned pits of microscopic dimensions. We report on different measurements such as the transmission of ultrasound, temperature increase inside the bag during sonication. Several applications of interest to other scientific activities are also demonstrated.","author":[{"dropping-particle":"","family":"Fernandez Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Verhaagen","given":"B.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Galdamez Perez","given":"Andres","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Castro-Hernandez","given":"Elena","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Zwieten","given":"Ralph","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schroen","given":"Karin","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Journal of Physics: Conference Series","id":"ITEM-2","issue":"012112","issued":{"date-parts":[["2015"]]},"page":"1-4","title":"A novel ultrasonic cavitation enhancer","type":"paper-conference","volume":"656"},"uris":[""]}],"mendeley":{"formattedCitation":"[121,154]","plainTextFormattedCitation":"[121,154]","previouslyFormattedCitation":"[121,154]"},"properties":{"noteIndex":0},"schema":""}[121,154] developed a scaled-up sonochemical microreactor with increased reproducibility and efficiency and was also able to clearly observe cavitation phenomena. The numbering up strategy applied by Van Zwieten et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2016.12.004","ISSN":"18732828","abstract":"Cavitation Intensifying Bags (CIBs), a novel reactor type for use with ultrasound, have been recently proposed as a scaled-up microreactor with increased energy efficiencies. We now report on the use of the CIBs for the preparation of emulsions out of hexadecane and an SDS aqueous solution. The CIBs have been designed in such a way that cavitation effects created by the ultrasound are increased. It was found that the CIBs were 60 times more effective in breaking up droplets than conventional bags, therewith showing a proof of principle for the CIBs for the preparation of emulsions. Droplets of 0.2 μm could easily be obtained. To our knowledge, no other technology results in the same droplet size more easily in terms of energy usage. Without depending on the wettability changes of the membrane, the CIBs score similarly as membrane emulsification, which is the most energy friendly emulsification method known in literature. Out of the frequencies used, 37 kHz was found to require the lowest treatment time. The treatment time decreased at higher temperatures. While the energy usage in the current non-optimised experiments was on the order of 107-109J/m3, which is comparable to that of a high-pressure homogenizer, we expect that the use of CIBs for the preparation of fine emulsions can still be improved considerably. The process presented can be applied for other uses such as water treatment, synthesis of nanomaterials and food processing.","author":[{"dropping-particle":"","family":"Zwieten","given":"Ralph","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schro?n","given":"Karin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernández Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"446-453","publisher":"Elsevier B.V.","title":"Emulsification in novel ultrasonic cavitation intensifying bag reactors","type":"article-journal","volume":"36"},"uris":[""]}],"mendeley":{"formattedCitation":"[143]","plainTextFormattedCitation":"[143]","previouslyFormattedCitation":"[143]"},"properties":{"noteIndex":0},"schema":""}[143] was carried out by immersing several cavitation intensification bags in an ultrasonic bath for the formation of a hexadecane and SDS aqueous emulsion, see Figure 7a, to obtain droplets diameter of 0.2 ?m. To characterize the cavitation activity, three methods have been used: sonochemiluminescence of luminol, hydrophone measurements, and terephthalic acid dosimetry. As mentioned previously these methods allowed for a reactor configuration that made effective use of the cavitation phenomenon, an essential aspect of scaled-up reactor designs and operation.Another strategy consists in enlarging channel size. This method has been used by Jamshidi et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.6b00696","ISBN":"1528-7483","ISSN":"15287505","abstract":"Continuous-flow crystallization of adipic acid in a millichannel chip equipped with a piezoelectric element is presented and investigated experimentally and numerically. A single, straight channel chip (cross section: 2 mm × 5 mm, length: 76 mm) made of glass, which is ultrasonically transparent, was designed and fabricated. The piezoelectric element allows studying the effect of different ultrasound frequencies in the kHz to MHz range. Ultrasound was applied in burst mode to reduce heating; this allowed operating at higher levels of input power. To accurately control the temperature of the fluid, Peltier elements were used to cool the bottom and top surfaces of the chip. Crystallization was performed in isothermal conditions, ensuring that the temperature and in turn the supersaturation were kept uniform along the channel. The effect of ultrasound frequency and sonication time was studied. Crystal size distributions at different operating conditions were obtained by laser diffraction. The distributions w...","author":[{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"4607-4619","title":"Investigation of the Effect of Ultrasound Parameters on Continuous Sonocrystallization in a Millifluidic Device","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[128]","plainTextFormattedCitation":"[128]","previouslyFormattedCitation":"[128]"},"properties":{"noteIndex":0},"schema":""}[128] for the design of an ultrasonic millifluidic device consisting of glass capillary channel with a cross-section of 2 × 5 mm? for the crystallization of adipic acid, see Figure 7b. This reactor has been designed with the use of numerical simulations to obtain the acoustic pressure distribution throughout the reactor. Smaller crystal sizes were obtained compared to conventional batch reactors. John et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115] also applied the same strategy for the design of the interval contact reactor, see Figure 7c, for liquid–-liquid extraction, discussed in section 3.1. The study focused on the effect of increasing the channel diameter size from 0.8 mm to 2 mm on the performance of p-nitrophenylacetate hydrolysis, with a better relative performance obtained with the 2 mm tubing.Depending on the application, the combination of the two scale up strategies previously described can be used. Gallaher et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Gallaher","given":"Amanda","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hannon","given":"Dominic","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Hardie","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issued":{"date-parts":[["2005"]]},"number":"WO2005/068068","publisher-place":"Great Britain","title":"Improvements in and relating to Sonochemistry","type":"patent"},"uris":[""]}],"mendeley":{"formattedCitation":"[147]","plainTextFormattedCitation":"[147]","previouslyFormattedCitation":"[147]"},"properties":{"noteIndex":0},"schema":""}[147] developed a sonocrystallization reactor device that consists of tubing with piezoelectric ring attached to it and oil flow is used to control temperature. Tubing diameter and number of reactor units can be adjusted depending on the production demand. Koiranen et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"abstract":"AN ultrasound crystallization device comprises a tubular crystallization reactor for conducting process fluid containing substance to be crystallized, an ultrasound source for radiating ultrasound to the tubular crystallization reactor, and a temperature-control structure for controlling the temperature of the process fluid with the aid of temperature-control fluid. The tubular crystallization reactor is shaped to conduct the process fluid to flow aound the ultrasound source, and the temperature-control structure comprises a flow-guide structure for guiding at least a part of the temperature-control fluid to flow around the ultrasound source. The flow-guide structure improves the accuracy of the temperature control of the process fluid and also the ability of the temperature control to react to changes.","author":[{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Ekberg","given":"Bjarne","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"H?kkinen","given":"Antti","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Varis","given":"Juha","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Louhi-Kultanen","given":"Marjatta","non-dropping-particle":"","parse-names":false,"suffix":""}],"id":"ITEM-1","issued":{"date-parts":[["2018"]]},"number":"WO2018/096205A1","title":"An ultrasound crystallization device and an ultrasound crystallization system","type":"patent"},"uris":[""]}],"mendeley":{"formattedCitation":"[148]","plainTextFormattedCitation":"[148]","previouslyFormattedCitation":"[148]"},"properties":{"noteIndex":0},"schema":""}[148] also combined the two strategies. The authors designed a reactor unit that consisted of a sonotrode with tubing wrapped as a helix, see Figure 5d. This method ensured a direct contact as described in section 3.1. Temperature control is achieved by using a heat transfer fluid flow. Numbering up was performed by running three units in parallel. Ezeanovi et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Ezeanowi","given":"Nnaemeka","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"International Process Intensification Conference 2019","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"2-3","title":"Effect of process parameters on a novel modular continuous crystallizer","type":"paper-conference","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[149]","plainTextFormattedCitation":"[149]","previouslyFormattedCitation":"[149]"},"properties":{"noteIndex":0},"schema":""}[149] were able to successfully apply this scaled-up reactor for a crystallization process, preventing clogging and promoting nucleation.As mentioned before, another approach to scale up is based on working under continuous conditions with larger vessels ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2006.10.012","ISSN":"13504177","abstract":"Biological cell lysis is known to be the rate-limiting step of anaerobic biosolids degradation. Shear forces generated by low frequency ultrasound can be used to disintegrate bacterial cells in sewage sludge. Thus, the quantity of dissolved organic substrate is increased. Consequently, the degradation rate and the biodegradability of organic biosolids mass are improved. Fundamental pilot-studies showed a significantly accelerated biosolids degradation with less digested sludge being produced and increased biogas production being attained. A full-scale ultrasound reactor system was developed for continuous operation under real life conditions on sewage treatment plants (STP). ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Nickel","given":"Klaus","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Neis","given":"Uwe","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"450-455","title":"Ultrasonic disintegration of biosolids for improved biodegradation","type":"article-journal","volume":"14"},"uris":[""]},{"id":"ITEM-2","itemData":{"DOI":"10.1016/S1350-4177(98)00041-8","ISSN":"13504177","abstract":"The degradation of aqueous solutions of pentachlorophenol (PCP) in a three-stage sonochemical reactor operating in the continuous flow mode has been investigated. The experimental reactor may be considered as a series of three high-frequency ultrasonic units. The influence of several parameters such as ultrasonic power, reactor volume and volumetric feed flow rate on the reactor performance is reported. Application of classical basic chemical engineering principles leads to a model that enables us to predict the PCP concentration within the reactor. In steady state, experimental conversion rates are shown to be in good agreement with model predictions. ? 1999 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Gondrexon","given":"N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Renaudin","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Petrier","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Boldo","given":"P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bernis","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gonthier","given":"Y.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-2","issued":{"date-parts":[["1999"]]},"page":"125-131","title":"Degradation of pentachlorophenol aqueous solutions using a continuous flow ultrasonic reactor: Experimental performance and modelling","type":"article-journal","volume":"5"},"uris":[""]},{"id":"ITEM-3","itemData":{"DOI":"10.1016/j.ultsonch.2009.12.003","ISBN":"1350-4177","PMID":"20060353","abstract":"In recent years, chemistry in flowing systems has become more prominent as a method of carrying out chemical transformations, ranging in scale from microchemistry up to kilogram-scale processes. Compared to classic batch ultrasound reactors, flow reactors stand out for their greater efficiency and flexibility as well as lower energy consumption. This paper presents a new ultrasonic flow reactor developed in our laboratory, a pilot system well suited for reaction scale up. This was applied to the transesterification of soybean oil with methanol for biodiesel production. This reaction is mass-transfer-limited initially because the two reactants are immiscible with each other, then because the glycerol phase separates together with most of the catalyst (Na or K methoxide). In our reactor a mixture of oil (1.6 L), methanol and sodium methoxide 30% in methanol (wt/wt ratio 80:19.5:0.5, respectively) was fully transesterified at about 45 ??C in 1 h (21.5 kHz, 600 W, flow rate 55 mL/min). The same result could be achieved together with a considerable reduction in energy consumption, by a two-step procedure: first a conventional heating under mechanical stirring (30 min at 45 ??C), followed by ultrasound irradiation at the same temperature (35 min, 600 W, flow rate 55 mL/min). Our studies confirmed that high-throughput ultrasound applications definitively require flow reactors. ?? 2009 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Cintas","given":"Pedro","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mantegna","given":"Stefano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gaudino","given":"Emanuela Calcio","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Cravotto","given":"Giancarlo","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-3","issued":{"date-parts":[["2010"]]},"page":"985-989","title":"A new pilot flow reactor for high-intensity ultrasound irradiation. Application to the synthesis of biodiesel","type":"article-journal","volume":"17"},"uris":[""]}],"mendeley":{"formattedCitation":"[155–157]","plainTextFormattedCitation":"[155–157]","previouslyFormattedCitation":"[155–157]"},"properties":{"noteIndex":0},"schema":""}[155–157]. Nickel and Neis ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2006.10.012","ISSN":"13504177","abstract":"Biological cell lysis is known to be the rate-limiting step of anaerobic biosolids degradation. Shear forces generated by low frequency ultrasound can be used to disintegrate bacterial cells in sewage sludge. Thus, the quantity of dissolved organic substrate is increased. Consequently, the degradation rate and the biodegradability of organic biosolids mass are improved. Fundamental pilot-studies showed a significantly accelerated biosolids degradation with less digested sludge being produced and increased biogas production being attained. A full-scale ultrasound reactor system was developed for continuous operation under real life conditions on sewage treatment plants (STP). ? 2006 Elsevier B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Nickel","given":"Klaus","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Neis","given":"Uwe","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2007"]]},"page":"450-455","title":"Ultrasonic disintegration of biosolids for improved biodegradation","type":"article-journal","volume":"14"},"uris":[""]}],"mendeley":{"formattedCitation":"[155]","plainTextFormattedCitation":"[155]","previouslyFormattedCitation":"[155]"},"properties":{"noteIndex":0},"schema":""}[155] developed a 29 L pilot scale sonochemical reactor, equipped with five 20 kHz transducers for studying the disintegration of biosolids. A second continuous large scale reactor example was used by Gondrexon et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/S1350-4177(98)00041-8","ISSN":"13504177","abstract":"The degradation of aqueous solutions of pentachlorophenol (PCP) in a three-stage sonochemical reactor operating in the continuous flow mode has been investigated. The experimental reactor may be considered as a series of three high-frequency ultrasonic units. The influence of several parameters such as ultrasonic power, reactor volume and volumetric feed flow rate on the reactor performance is reported. Application of classical basic chemical engineering principles leads to a model that enables us to predict the PCP concentration within the reactor. In steady state, experimental conversion rates are shown to be in good agreement with model predictions. ? 1999 Elsevier Science B.V. All rights reserved.","author":[{"dropping-particle":"","family":"Gondrexon","given":"N.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Renaudin","given":"V.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Petrier","given":"C.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Boldo","given":"P.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Bernis","given":"A.","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gonthier","given":"Y.","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["1999"]]},"page":"125-131","title":"Degradation of pentachlorophenol aqueous solutions using a continuous flow ultrasonic reactor: Experimental performance and modelling","type":"article-journal","volume":"5"},"uris":[""]}],"mendeley":{"formattedCitation":"[156]","plainTextFormattedCitation":"[156]","previouslyFormattedCitation":"[156]"},"properties":{"noteIndex":0},"schema":""}[156] for the degradation of aqueous solution of pentachlorophenol. This reactor was designed as a three stage distillation column with a 500 kHz transducer attached below each stage.As a conclusion, the choice of the scale-up strategy not only depends on the understanding of the ultrasonic mechanisms but also on the coupling between ultrasonic device and reactor. In fact, direct coupling between piezoelectric devices and reactors, as described in section 3.1, might be more suitable for numbering up whereas coupling of Langevin transducer with tubing, as the hybrid reactor developed by John et al. ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115] might be for scaling out. Combining the two scale-up strategies seems promising to fulfill the requirements of the chemical industry, as small scale reactors offer a better control of the final product properties with increased production rates. Despite the need of further studies, currently on-going efforts on numerical characterization of the scalability of such reactors show promise to increase the range of applications.Figure 7. Examples of scaled-up reactor designs: (a) cCavitation iIntensification bBag immersed in an ultrasonic bath (numbering up), reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.ultsonch.2016.12.004","ISSN":"18732828","abstract":"Cavitation Intensifying Bags (CIBs), a novel reactor type for use with ultrasound, have been recently proposed as a scaled-up microreactor with increased energy efficiencies. We now report on the use of the CIBs for the preparation of emulsions out of hexadecane and an SDS aqueous solution. The CIBs have been designed in such a way that cavitation effects created by the ultrasound are increased. It was found that the CIBs were 60 times more effective in breaking up droplets than conventional bags, therewith showing a proof of principle for the CIBs for the preparation of emulsions. Droplets of 0.2 μm could easily be obtained. To our knowledge, no other technology results in the same droplet size more easily in terms of energy usage. Without depending on the wettability changes of the membrane, the CIBs score similarly as membrane emulsification, which is the most energy friendly emulsification method known in literature. Out of the frequencies used, 37 kHz was found to require the lowest treatment time. The treatment time decreased at higher temperatures. While the energy usage in the current non-optimised experiments was on the order of 107-109J/m3, which is comparable to that of a high-pressure homogenizer, we expect that the use of CIBs for the preparation of fine emulsions can still be improved considerably. The process presented can be applied for other uses such as water treatment, synthesis of nanomaterials and food processing.","author":[{"dropping-particle":"","family":"Zwieten","given":"Ralph","non-dropping-particle":"Van","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Verhaagen","given":"Bram","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Schro?n","given":"Karin","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Fernández Rivas","given":"David","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Ultrasonics Sonochemistry","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"446-453","publisher":"Elsevier B.V.","title":"Emulsification in novel ultrasonic cavitation intensifying bag reactors","type":"article-journal","volume":"36"},"uris":[""]}],"mendeley":{"formattedCitation":"[143]","plainTextFormattedCitation":"[143]","previouslyFormattedCitation":"[143]"},"properties":{"noteIndex":0},"schema":""}[143], copyright Elsevier. (b) Scale out strategy for sonocrystallization, reactor consisting of a piezoelectric plate attached to a glass capillary, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1021/acs.cgd.6b00696","ISBN":"1528-7483","ISSN":"15287505","abstract":"Continuous-flow crystallization of adipic acid in a millichannel chip equipped with a piezoelectric element is presented and investigated experimentally and numerically. A single, straight channel chip (cross section: 2 mm × 5 mm, length: 76 mm) made of glass, which is ultrasonically transparent, was designed and fabricated. The piezoelectric element allows studying the effect of different ultrasound frequencies in the kHz to MHz range. Ultrasound was applied in burst mode to reduce heating; this allowed operating at higher levels of input power. To accurately control the temperature of the fluid, Peltier elements were used to cool the bottom and top surfaces of the chip. Crystallization was performed in isothermal conditions, ensuring that the temperature and in turn the supersaturation were kept uniform along the channel. The effect of ultrasound frequency and sonication time was studied. Crystal size distributions at different operating conditions were obtained by laser diffraction. The distributions w...","author":[{"dropping-particle":"","family":"Jamshidi","given":"Rashid","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Rossi","given":"Damiano","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Saffari","given":"Nader","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gavriilidis","given":"Asterios","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Mazzei","given":"Luca","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"Crystal Growth and Design","id":"ITEM-1","issued":{"date-parts":[["2016"]]},"page":"4607-4619","title":"Investigation of the Effect of Ultrasound Parameters on Continuous Sonocrystallization in a Millifluidic Device","type":"article-journal","volume":"16"},"uris":[""]}],"mendeley":{"formattedCitation":"[128]","plainTextFormattedCitation":"[128]","previouslyFormattedCitation":"[128]"},"properties":{"noteIndex":0},"schema":""}[128], copyright ACS publications. (c) Scale out strategy for liquid–-liquid extraction, reactor consisting of PFA tubing immersed in an hybrid ultrasonic reactor, reprinted with permission from ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"DOI":"10.1016/j.cherd.2017.06.025","ISSN":"02638762","abstract":"This work aims at constructing a design which integrates a direct (solid) contact method with temperature control for chemical process applications. To realise this integration a two-step approach is proposed. Firstly, temperature control is achieved by suspending the tubing in a temperature controlled and sonicated liquid medium (indirect contact). Secondly, direct contact elements are introduced at regular intervals along the tubing. Therefore, this design is termed the hybrid contact reactor, as it incorporates both direct and indirect approaches of ultrasound transfer. Furthermore, two possible configurations, open and closed interval connection to the tubing, were assessed. Both hybrid reactors performed better than the indirect contact reactor (20–27% increase in yield) for residence times of less than 45 s and similar for residence times above. Even though the performance of the two hybrid designs was similar the closed interval resulted in more reproducible and distinct yields. This configuration was then scaled up 10 times in internal volume using a 2 mm ID tube. This design showed a relative performance similar to the interval contact design which gave the highest yields thus far for the same operating conditions.","author":[{"dropping-particle":"","family":"John","given":"Jinu Joseph","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Kuhn","given":"Simon","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Braeken","given":"Leen","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Gerven","given":"Tom","non-dropping-particle":"Van","parse-names":false,"suffix":""}],"container-title":"Chemical Engineering Research and Design","id":"ITEM-1","issued":{"date-parts":[["2017"]]},"page":"146-155","publisher":"Institution of Chemical Engineers","title":"Temperature controlled interval contact design for ultrasound assisted liquid–liquid extraction","type":"article-journal","volume":"125"},"uris":[""]}],"mendeley":{"formattedCitation":"[115]","plainTextFormattedCitation":"[115]","previouslyFormattedCitation":"[115]"},"properties":{"noteIndex":0},"schema":""}[115], copyright Elsevier. (d) Combination of scale out and numbering up strategies for a sonocrystallization process, reactor consisting of a sonotrode and a reactor wrapped as a helix around the sonotrode, reprinted with permission from the authors ADDIN CSL_CITATION {"citationItems":[{"id":"ITEM-1","itemData":{"author":[{"dropping-particle":"","family":"Ezeanowi","given":"Nnaemeka","non-dropping-particle":"","parse-names":false,"suffix":""},{"dropping-particle":"","family":"Koiranen","given":"Tuomas","non-dropping-particle":"","parse-names":false,"suffix":""}],"container-title":"International Process Intensification Conference 2019","id":"ITEM-1","issued":{"date-parts":[["2019"]]},"page":"2-3","title":"Effect of process parameters on a novel modular continuous crystallizer","type":"paper-conference","volume":"2"},"uris":[""]}],"mendeley":{"formattedCitation":"[149]","plainTextFormattedCitation":"[149]","previouslyFormattedCitation":"[149]"},"properties":{"noteIndex":0},"schema":""}[149].6. ConclusionsSmall scale flow reactors have long been regarded as the way forward for various chemical processes, especially when considering switching from batch to continuous. Integrating ultrasound has brought this technology one step closer into making this a realization by, not only mitigating the inherent problems of microreactors, but also increasing their versatility and broadening applicability through the different mechanisms associated with ultrasound. Detailed studies of these mechanisms make it possible to have a broader outlook on different applications, having already shown promise for several. From lab to pilot scale ultrasonic flow reactors have proven to outperform conventional equipment, however, scaling of these reactors to meet the output of their conventional counterparts is still a work in progress. Problems regarding temperature control, uniform ultrasound distribution and the low energy transfer efficiencies are currently being investigated. Design techniques for larger scales are making it possible, for instance, to fabricate reactors in such a way to distribute the ultrasound energy where required, reducing the power consumption and the need for excessive cooling. Whereas reactor characterization identifies the most active zones in reactors, making it possible to utilize ultrasonic effects to a larger extent. Both these methods have also been used to promote these effects to such an extent that there are various scaled designs currently being tested for industrial applications.Funding: Please add: “This research received no external funding” or “This research was funded by NAME OF FUNDER, grant number XXX” and “The APC was funded by XXX”. Check carefully that the details given are accurate and use the standard spelling of funding agency names at , any errors may affect your future funding.Author Contributions: Conceptualization, Z.D.; investigation, Z.D, K.M., A.U., C.D.; resources, Z.D, K.M., A.U., C.D.; writing—original draft preparation, Z.D, K.M., A.U., C.D.; writing—review and editing, Z.D, K.M., A.U., C.D. and S.K.; supervision, S.K.; funding acquisition, S.K.Acknowledgments: C.D. is supported by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721290 (Project website: ). S.K. acknowledges funding from the European Research Council under the ERC Starting Grant Agreement n. 677169–MicroParticleControl.Conflicts of Interest: The authors declare no conflict of interestReferencesADDIN Mendeley Bibliography CSL_BIBLIOGRAPHY 1.J?hnisch, K.; Hessel, V.; L?we, H.; Baerns, M. Chemistry in Microstructured Reactors. Angew. Chemie - Int. 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