Effective Transport Template for Particle Separation in Microfluidic Bumper Arrays

Abstract

Microfluidic bumper arrays are increasingly being used for the size-based sorting of particle suspensions. The separation mechanism is based on the interaction between a spatially periodic array of obstacles and the suspended particles as they are driven through the obstacle lattice either by volume forces or by the Stokesian drag of the surrounding fluid. By this mechanism, a focused stream of suspended particles of different sizes entering the lattice splits into different currents, each entraining assigned ranges of particle dimensions, and each characterized by a specific angle with respect to the main device axis. In this work, we build up on recent results stemming from macrotransport process theory to derive a closed-form solution for the steady-state distribution of advecting-diffusing particles in the presence of anisotropic dispersion, which typically characterizes large-scale behavior of particle motion through the periodic lattice. Attention is focused on separation resolution, that ultimately controls the feasibility of the separation in specific applications.