An on-chip, multichannel droplet sorter using standing surface acoustic waves.

The emerging field of droplet microfluidics requires effective on-chip handling and sorting of droplets. In this work, we demonstrate a microfluidic device that is capable of sorting picoliter water-in-oil droplets into multiple outputs using standing surface acoustic waves (SSAW). This device integrates a single-layer microfluidic channel with interdigital transducers (IDTs) to achieve on-chip droplet generation and sorting. Within the SSAW field, water-in-oil droplets experience an acoustic radiation force and are pushed toward the acoustic pressure node. As a result, by tuning the frequency of the SSAW excitation, the position of the pressure nodes can be changed and droplets can be sorted to different outlets at rates up to 222 droplets s(-1). With its advantages in simplicity, controllability, versatility, noninvasiveness, and capability to be integrated with other on-chip components such as droplet manipulation and optical detection units, the technique presented here could be valuable for the development of droplet-based micro total analysis systems (μTAS).

[1]  Leslie Y Yeo,et al.  Surface acoustic wave concentration of particle and bioparticle suspensions , 2007, Biomedical microdevices.

[2]  Joseph C Liao,et al.  Molecular detection of bacterial pathogens using microparticle enhanced double-stranded DNA probes. , 2011, Analytical chemistry.

[3]  Hairong Zheng,et al.  Precise and programmable manipulation of microbubbles by two-dimensional standing surface acoustic waves , 2012 .

[4]  S. Quake,et al.  Dynamic pattern formation in a vesicle-generating microfluidic device. , 2001, Physical review letters.

[5]  Daniel Ahmed,et al.  Tunable, pulsatile chemical gradient generation via acoustically driven oscillating bubbles. , 2013, Lab on a chip.

[6]  Daniel Ahmed,et al.  Focusing microparticles in a microfluidic channel with standing surface acoustic waves (SSAW). , 2008, Lab on a chip.

[7]  John E. Cunningham,et al.  Formation and manipulation of two-dimensional arrays of micron-scale particles in microfluidic systems by surface acoustic waves , 2009 .

[8]  D. Weitz,et al.  Electric control of droplets in microfluidic devices. , 2006, Angewandte Chemie.

[9]  Lin Wang,et al.  Standing surface acoustic wave (SSAW) based multichannel cell sorting. , 2012, Lab on a chip.

[10]  T. Laurell,et al.  Free flow acoustophoresis: microfluidic-based mode of particle and cell separation. , 2007, Analytical chemistry.

[11]  Feng Guo,et al.  Droplet electric separator microfluidic device for cell sorting , 2010 .

[12]  François Gallaire,et al.  Thermocapillary valve for droplet production and sorting. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[13]  Andreas Manz,et al.  Latest developments in micro total analysis systems. , 2010, Analytical chemistry.

[14]  Kelly Karns,et al.  Human tear protein analysis enabled by an alkaline microfluidic homogeneous immunoassay. , 2011, Analytical chemistry.

[15]  Andrew D Griffiths,et al.  A completely in vitro ultrahigh-throughput droplet-based microfluidic screening system for protein engineering and directed evolution. , 2012, Lab on a chip.

[16]  Mengying Zhang,et al.  Real-time detection, control, and sorting of microfluidic droplets. , 2007, Biomicrofluidics.

[17]  I-Kao Chiang,et al.  Surface Acoustic Wave Driven Light Shutters Using Polymer‐Dispersed Liquid Crystals , 2011, Advanced materials.

[18]  Yang Liu,et al.  Particle separation in microfluidics using a switching ultrasonic field. , 2011, Lab on a chip.

[19]  Sehyun Shin,et al.  Size-dependent microparticles separation through standing surface acoustic waves , 2011 .

[20]  Mario Markus,et al.  Multipeaked probability distributions of recurrence times. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[21]  H. Stone,et al.  Formation of dispersions using “flow focusing” in microchannels , 2003 .

[22]  I-Kao Chiang,et al.  On-chip manipulation of single microparticles, cells, and organisms using surface acoustic waves , 2012, Proceedings of the National Academy of Sciences.

[23]  Po-Hsun Huang,et al.  Tunable nanowire patterning using standing surface acoustic waves. , 2013, ACS nano.

[24]  Haakan N Joensson,et al.  Droplet size based separation by deterministic lateral displacement-separating droplets by cell--induced shrinking. , 2011, Lab on a chip.

[25]  A. Abate,et al.  Microfluidic sorting with high-speed single-layer membrane valves , 2010 .

[26]  Helen Song,et al.  Reactions in droplets in microfluidic channels. , 2006, Angewandte Chemie.

[27]  Avishay Bransky,et al.  Advanced microfluidic droplet manipulation based on piezoelectric actuation , 2010, Biomedical microdevices.

[28]  Daniel Ahmed,et al.  A millisecond micromixer via single-bubble-based acoustic streaming. , 2009, Lab on a chip.

[29]  K. Yosioka,et al.  Acoustic radiation pressure on a compressible sphere , 1955 .

[30]  Amy E. Herr,et al.  Microfluidic integration for automated targeted proteomic assays , 2012, Proceedings of the National Academy of Sciences.

[31]  A. Manz,et al.  Revisiting lab-on-a-chip technology for drug discovery , 2012, Nature Reviews Drug Discovery.

[32]  Mengying Zhang,et al.  Generation and manipulation of “smart” droplets , 2009 .

[33]  A. Abate,et al.  Surface acoustic wave (SAW) directed droplet flow in microfluidics for PDMS devices. , 2009, Lab on a chip.

[34]  Jinjie Shi,et al.  Tunable patterning of microparticles and cells using standing surface acoustic waves. , 2012, Lab on a chip.

[35]  Gwo-Bin Lee,et al.  A droplet-based microfluidic system capable of droplet formation and manipulation , 2009 .

[36]  Thomas Laurell,et al.  Carrier medium exchange through ultrasonic particle switching in microfluidic channels. , 2005, Analytical chemistry.

[37]  I-Kao Chiang,et al.  Three-dimensional continuous particle focusing in a microfluidic channel via standing surface acoustic waves (SSAW). , 2011, Lab on a chip.

[38]  John E. Cunningham,et al.  Alignment of particles in microfluidic systems using standing surface acoustic waves , 2008 .

[39]  Satoshi Itoh,et al.  32 Neのスペクトロスコピーと「island of inversion」 | 文献情報 | J-GLOBAL 科学技術総合リンクセンター , 2009 .

[40]  T. Huang,et al.  Continuous particle separation in a microfluidic channel via standing surface acoustic waves (SSAW). , 2009, Lab on a chip.

[41]  A. Theberge,et al.  Microdroplets in microfluidics: an evolving platform for discoveries in chemistry and biology. , 2010, Angewandte Chemie.

[42]  R. Westervelt,et al.  Dielectrophoretic manipulation of drops for high-speed microfluidic sorting devices , 2006 .

[43]  Yuliang Xie,et al.  Single-shot characterization of enzymatic reaction constants Km and kcat by an acoustic-driven, bubble-based fast micromixer. , 2012, Analytical chemistry.

[44]  A. Griffiths,et al.  High-resolution dose–response screening using droplet-based microfluidics , 2011, Proceedings of the National Academy of Sciences of the United States of America.

[45]  G. Luo,et al.  On-demand microfluidic droplet manipulation using hydrophobic ferrofluid as a continuous-phase. , 2011, Lab on a chip.

[46]  D A Weitz,et al.  Surface acoustic wave actuated cell sorting (SAWACS). , 2010, Lab on a chip.

[47]  Sehyun Shin,et al.  Density-dependent separation of encapsulated cells in a microfluidic channel by using a standing surface acoustic wave. , 2012, Biomicrofluidics.

[48]  M. Lapsley,et al.  A droplet-based, optofluidic device for high-throughput, quantitative bioanalysis. , 2012, Analytical chemistry.

[49]  Viktor Stein,et al.  Continuous-flow polymerase chain reaction of single-copy DNA in microfluidic microdroplets. , 2009, Analytical chemistry.

[50]  Robert P. Luoma,et al.  Digital microfluidic magnetic separation for particle-based immunoassays. , 2012, Analytical chemistry.

[51]  Tony Jun Huang,et al.  Surface acoustic wave (SAW) acoustophoresis: now and beyond. , 2012, Lab on a chip.

[52]  Monpichar Srisa-Art,et al.  High-throughput DNA droplet assays using picoliter reactor volumes. , 2007, Analytical chemistry.

[53]  Daniel Ahmed,et al.  A fast microfluidic mixer based on acoustically driven sidewall-trapped microbubbles , 2009 .

[54]  Mandy L Y Sin,et al.  In situ electrokinetic enhancement for self-assembled-monolayer-based electrochemical biosensing. , 2012, Analytical chemistry.

[55]  Hairong Zheng,et al.  Acoustic aligning and trapping of microbubbles in an enclosed PDMS microfluidic device , 2011 .

[56]  Kangsun Lee,et al.  Concurrent droplet charging and sorting by electrostatic actuation. , 2009, Biomicrofluidics.

[57]  Andrew D Griffiths,et al.  Miniaturising the laboratory in emulsion droplets. , 2006, Trends in biotechnology.

[58]  James Friend,et al.  The extraction of liquid, protein molecules and yeast cells from paper through surface acoustic wave atomization. , 2010, Lab on a chip.

[59]  Fei Yan,et al.  Transportation of single cell and microbubbles by phase-shift introduced to standing leaky surface acoustic waves. , 2011, Biomicrofluidics.

[60]  Tony Jun Huang,et al.  Microfluidic diagnostics for the developing world. , 2012, Lab on a chip.

[61]  Monpichar Srisa-Art,et al.  Microdroplets: a sea of applications? , 2008, Lab on a chip.

[62]  Christoph A. Merten,et al.  Droplet-based microfluidic platforms for the encapsulation and screening of Mammalian cells and multicellular organisms. , 2008, Chemistry & biology.

[63]  Leslie Y Yeo,et al.  Rapid production of protein-loaded biodegradable microparticles using surface acoustic waves. , 2009, Biomicrofluidics.

[64]  Kangsun Lee,et al.  On-demand electrostatic droplet charging and sorting. , 2011, Biomicrofluidics.

[65]  D. Weitz,et al.  Fluorescence-activated droplet sorting (FADS): efficient microfluidic cell sorting based on enzymatic activity. , 2009, Lab on a chip.

[66]  Tony Jun Huang,et al.  Exploiting mechanical biomarkers in microfluidics. , 2012, Lab on a chip.

[67]  Jean-Louis Viovy,et al.  Microfluidic high-throughput encapsulation and hydrodynamic self-sorting of single cells , 2008, Proceedings of the National Academy of Sciences.

[68]  Aaron R Wheeler,et al.  Microfluidic device for single-cell analysis. , 2003, Analytical chemistry.

[69]  Yuliang Xie,et al.  Optoacoustic tweezers: a programmable, localized cell concentrator based on opto-thermally generated, acoustically activated, surface bubbles. , 2013, Lab on a chip.

[70]  Andreas Manz,et al.  On-chip free-flow magnetophoresis: continuous flow separation of magnetic particles and agglomerates. , 2004, Analytical chemistry.

[71]  R. Wunenburger,et al.  Laser switching and sorting for high speed digital microfluidics , 2008 .

[72]  D. Weitz,et al.  Droplet microfluidics for high-throughput biological assays. , 2012, Lab on a chip.

[73]  Changyang Lee,et al.  Microfluidic droplet sorting with a high frequency ultrasound beam. , 2012, Lab on a chip.

[74]  Daniel Ahmed,et al.  Acoustic tweezers: patterning cells and microparticles using standing surface acoustic waves (SSAW). , 2009, Lab on a chip.