Highly viscous fluids in pressure actuated flow focusing devices

Microfluidic flow focusing devices (mFFD) are currently used to produce microdroplets and emulsions. Recently, it has been demonstrated that they are well adapted to the encapsulation of biologic objects like proteins and cells. Liquids used for encapsulation are most of the time dilute polymeric solutions with relatively low viscosity. However, investigations have started to assess the possibility of encapsulation with more concentrated solutions, like semi-dilute solutions of alginates. In this work, we analyze the behavior of highly viscous alginate solutions in pressure actuated FFDs. Experiments have been performed using alginate solutions with a viscosity up to 2600 times that of water. In parallel, an analytical model of the flow in the different branches of the FFD has been derived that explains the limits of the droplet regime. This model can be used to produce scaling rules for FFDs, facilitating the dimensioning of FFDs according to the desired size of the capsules. Finally, an example of encapsulation of Jurkat cells in a high viscosity Keltone alginate capsule is given.

[1]  G. Whitesides,et al.  Mechanism for flow-rate controlled breakup in confined geometries: a route to monodisperse emulsions. , 2005, Physical review letters.

[2]  H. Ijima,et al.  Higher Viscous Solution Induces Smaller Droplets for Cell‐Enclosing Capsules in a Co‐flowing Stream , 2008, Biotechnology progress.

[3]  R. Bird.  Dynamics of Polymeric Liquids , 1977 .

[4]  K. Draget,et al.  Synergistic effects in semidilute mixed solutions of alginate and lactose-modified chitosan (chitlac). , 2007, Biomacromolecules.

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

[6]  G. Whitesides,et al.  Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids , 2008 .

[7]  Zhengdong Cheng,et al.  Cell encapsules with tunable transport and mechanical properties. , 2007, Biomicrofluidics.

[8]  E. Morris,et al.  Concentration and shear rate dependence of viscosity in random coil polysaccharide solutions , 1981 .

[9]  E. Kumacheva,et al.  Continuous microfluidic reactors for polymer particles. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[10]  P. de Vos,et al.  Alginate-based microcapsules for immunoisolation of pancreatic islets. , 2006, Biomaterials.

[11]  M. Yovanovich,et al.  Pressure Drop of Fully-Developed, Laminar Flow in Microchannels of Arbitrary Cross-Section , 2006 .

[12]  Brian J. Adzima,et al.  Institute of Physics Publishing Journal of Micromechanics and Microengineering Pressure Drops for Droplet Flows in Microfluidic Channels , 2022 .

[13]  Somchai Wongwises,et al.  Two-phase flow pattern maps for vertical upward gas-liquid flow in mini-gap channels , 2004 .

[14]  D. Beebe,et al.  Controlled microfluidic interfaces , 2005, Nature.

[15]  Helen Song,et al.  Formation of droplets and mixing in multiphase microfluidics at low values of the Reynolds and the capillary numbers , 2003 .

[16]  Jean Berthier,et al.  Microdrops and digital microfluidics , 2008 .

[17]  Hariprasad J. Subramani,et al.  Dripping-jetting transitions in a dripping faucet. , 2004, Physical review letters.

[18]  George M. Whitesides,et al.  An Axisymmetric Flow‐Focusing Microfluidic Device , 2005 .

[19]  Michael J. Vellekoop,et al.  An integrated flow-cell for full sample stream control , 2009 .

[20]  Vittorio Cristini,et al.  Monodispersed microfluidic droplet generation by shear focusing microfluidic device , 2006 .

[21]  Magalie Faivre,et al.  Microfluidic flow focusing: Drop size and scaling in pressure versus flow‐rate‐driven pumping , 2005, Electrophoresis.

[22]  D. Weitz,et al.  Dripping to jetting transitions in coflowing liquid streams. , 2007, Physical review letters.

[23]  Stephen B. Dunnett,et al.  On-chip alginate microencapsulation of functional cells , 2008 .

[24]  Yuchao Zhao,et al.  Liquid‐liquid two‐phase flow patterns in a rectangular microchannel , 2006 .

[25]  Kanaka Hettiarachchi,et al.  Controlled microfluidic encapsulation of cells, proteins, and microbeads in lipid vesicles. , 2006, Journal of the American Chemical Society.

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

[27]  C. Batt,et al.  Hydrodynamic focusing with a microlithographic manifold: controlling the vertical position of a focused sample , 2009 .