Designing Constricted Microchannels To Selectively Entrap Soft Particles

Abstract

The entrapment of micron-sized particles in microscopic pores is beneficial for the efficient functioning of filtration systems and microfluidic devices for analyzing individual biological cells. To optimize the performance of these systems, it is important to isolate factors that regulate the passage of particles through micron-sized constrictions. Using computational modeling, we investigate the fluid-driven motion of compliant particles through constrictions, which are formed by pillars that extend from the top and bottom walls of a microchannel. The particles are modeled as fluid-filled capsules that have elastic shells and simulate biological cells or polymeric microcapsules. The separation between the pillars is ∼10% larger than the diameter of the undeformed capsules. We introduce an attractive interaction between the capsules and the tops of the pillars and vary the elasticity of both the capsules and pillars. Surprisingly, we find that this simple system shows a selectivity toward capsules of int...