(412h) Particle Transport and Damage in Confined Channels

The transport of suspended particles and cells in confined channels with contractions, branches, obstacles, etc. has applications in microfluidics, membrane separations, hydraulic fracturing, particle sorting, cell injection, and other processes. Critical issues include the particle transport rate, the downstream distributions of particle locations, and the potential for damage if particles (cells, in particular) hit corners or pass through regions of high extensional stresses.

In this work, we adapt the moving-frame boundary-integral method, originally developed to study particle sorting (Zinchenko, Ashley & Davis, 2012; Ashley, Bowman & Davis, 2013), to follow the motion of spherical particles in microchannels of complex shapes. One application is the delivery of biological cells through a syringe and needle to a tissue. Previous studies have shown that typically 40% or more of cells are damaged and die from the injection process (Aguado et al., 2012), so there is considerable interest in understanding and alleviating the causes of cell damage. Our initial simulations show that 20% or more of the cells may hit an internal corner within the delivery device during the injection process, causing a high level of localized stress. Additional cells experience high extensional stressors during the transition from the wide syringe barrel to the narrow needle bore. Another application is the focusing of particles and cells, which has practical applications for targeted transport and sorting. Interactions with sharp corners (provided they don’t cause undesired damage) give rise to focused streams of particles and corresponding shadow regions free of particles. Simulations for both of these applications will be presented.

Aguado, B.A., W. Mulyasasmita, J.Su, K. J. Lampe, and S. C. Heilshorn, “Improving Viability of Stem Cells During Syringe Needle Flow Through the Design of Hydrogel Carriers,” Tissue Engineering: Part A 18, 806-815 (2012).

Ashley, J.F., C.N. Bowman, and R.H. Davis, “Hydrodynamic Separation of Particles using Pinched-flow Fractionation,” AIChE Journal 59, 3444-3457 (2013).

Zinchenko, A.Z., J.F. Ashley, and R.H. Davis, “A Moving-frame Boundary-integral Method for Particle Transport in Microchannels of Complex Shape,” Physics of Fluids 24, 043302-1 – 043302-32 (2012).