Breakup length of AC electrified jets in a microfluidic flow-focusing junction

AbstractElectroactuation of liquid–liquid interfaces offers promising methods to actively modulate droplet formation in droplet-based microfluidic systems. Here, flow-focusing junctions are coupled to electrodes to control droplet production in the well-known jetting regime. In this regime, a convective instability develops leading to droplet formation at the end of a thin and uniform, long liquid finger. We show that in AC electric fields, the jet length is a function of both the magnitude of the applied voltage and the electrical parameters such as the frequency of the AC field and the conductivity of the dispersed phase. We explain that dependency using a simple transmission line model along the liquid jet. An optimum frequency to maximize the liquid ligament length is experimentally observed. Such length simply cannot be obtained by other means under the same operating conditions, in the absence of the AC signal. At low frequency, we reach a transition from a well-behaved, uniform jet brought about near the optimum frequency to highly unstable liquid structures in which axisymmetry is lost rather abruptly.

[1]  A. Gañán-Calvo,et al.  Spatiotemporal instability of a confined capillary jet. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[2]  S. Tan,et al.  Generation and manipulation of monodispersed ferrofluid emulsions: the effect of a uniform magnetic field in flow-focusing and T-junction configurations. , 2011, Physical review. E, Statistical, nonlinear, and soft matter physics.

[3]  Christoph A. Merten,et al.  Functional single-cell hybridoma screening using droplet-based microfluidics , 2012, Proceedings of the National Academy of Sciences.

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

[5]  Elena Castro-Hernández,et al.  Slender-body theory for the generation of micrometre-sized emulsions through tip streaming , 2012, Journal of Fluid Mechanics.

[6]  Alfonso M Gañán-Calvo,et al.  Electro-flow focusing: the high-conductivity low-viscosity limit. , 2006, Physical review letters.

[7]  Charles N. Baroud,et al.  Droplet microfluidics driven by gradients of confinement , 2013, Proceedings of the National Academy of Sciences.

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

[9]  T. Franke,et al.  SAW-controlled drop size for flow focusing. , 2013, Lab on a chip.

[10]  Stephan Herminghaus,et al.  Electroactuation of fluid using topographical wetting transitions. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[11]  David A. Weitz,et al.  Controlled production of emulsion drops using an electric field in a flow-focusing microfluidic device , 2007 .

[12]  T. Cubaud,et al.  Capillary threads and viscous droplets in square microchannels , 2008 .

[13]  Armand Ajdari,et al.  Stability of a jet in confined pressure-driven biphasic flows at low Reynolds number in various geometries. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[14]  J. R. Melcher,et al.  Electrohydrodynamics: A Review of the Role of Interfacial Shear Stresses , 1969 .

[15]  David A. Weitz,et al.  Valve-based flow focusing for drop formation , 2009 .

[16]  Adam Sciambi,et al.  Accurate microfluidic sorting of droplets at 30 kHz. , 2015, Lab on a chip.

[17]  Hans C. Mayer,et al.  Microscale tipstreaming in a microfluidic flow focusing device , 2006 .

[18]  L. Mazutis,et al.  Quantitative and sensitive detection of rare mutations using droplet-based microfluidics. , 2011, Lab on a chip.

[19]  Nam-Trung Nguyen,et al.  Manipulation of ferrofluid droplets using planar coils , 2006 .

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

[21]  Joseph Katz,et al.  Turbulent shearing of crude oil mixed with dispersants generates long microthreads and microdroplets. , 2010, Physical review letters.

[22]  Jérémy Vrignon,et al.  The Microfluidic Jukebox , 2014, Scientific Reports.

[23]  J. Baret,et al.  Microfluidic flow-focusing in ac electric fields. , 2014, Lab on a chip.

[24]  George M Whitesides,et al.  Cofabrication of electromagnets and microfluidic systems in poly(dimethylsiloxane). , 2006, Angewandte Chemie.

[25]  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.

[26]  Alfonso M. Gañán-Calvo,et al.  The combination of electrospray and flow focusing , 2006 .

[27]  Alfonso M. Gañán-Calvo,et al.  Generation of Steady Liquid Microthreads and Micron-Sized Monodisperse Sprays in Gas Streams , 1998 .

[28]  Charles N. Baroud,et al.  Quantitative analysis of the dripping and jetting regimes in co-flowing capillary jets , 2010, 1011.2428.

[29]  Andrew D Griffiths,et al.  Directed evolution by in vitro compartmentalization , 2006, Nature Methods.

[30]  Alberto Fernandez-Nieves,et al.  Absolute instability of a liquid jet in a coflowing stream. , 2008, Physical review letters.

[31]  Armand Ajdari,et al.  Stability of a jet in confined pressure-driven biphasic flows at low reynolds numbers. , 2007, Physical review letters.

[32]  R G Ashcroft,et al.  Commercial high speed machines open new opportunities in high throughput flow cytometry (HTFC). , 2000, Journal of immunological methods.

[33]  S. M. Sohel Murshed,et al.  Thermally controlled droplet formation in flow focusing geometry: formation regimes and effect of nanoparticle suspension , 2008 .

[34]  S. Herminghaus,et al.  Transport dynamics in open microfluidic grooves. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[35]  E. Villermaux,et al.  Physics of liquid jets , 2008 .

[36]  Erich J. Windhab,et al.  Drop formation in a co-flowing ambient fluid , 2004 .

[37]  A. Abate,et al.  Ultrahigh-throughput screening in drop-based microfluidics for directed evolution , 2010, Proceedings of the National Academy of Sciences.

[38]  S. Vanapalli,et al.  Electrowetting --A versatile tool for controlling microdrop generation , 2008, The European physical journal. E, Soft matter.

[39]  A. Gañán-Calvo.  Unconditional jetting. , 2008, Physical review. E, Statistical, nonlinear, and soft matter physics.

[40]  Alfonso M. Gañán-Calvo,et al.  Focusing capillary jets close to the continuum limit , 2007 .

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

[42]  S. Ramo,et al.  Fields and Waves in Communication Electronics , 1966 .

[43]  S. Herminghaus,et al.  Droplet based microfluidics , 2012, Reports on progress in physics. Physical Society.