(367c) Dispersion of Suspension Plugs in Microchannels

Plugs of microbeads can be used as a model for understanding the behavior of suspensions in micofluidic devices.  Despite a large volume of literature in the field of microfluidic suspension flows;  the fundamental understanding of the dispersion of hard and soft particle suspension plugs of finite length has not be studied in detail.  Here we focus on the dispersion characteristics of non-Brownian, low Reynolds number bead suspensions in microfluidic channels. The effect of initial plug lengths (10μm -15μm), bead size(1μm -3μm DI) and dilution(25%-75%) on the early stages of dispersion of these beads in a pressure driven flow will be presented. Plugs of magnetic beads are mixed with fluorescent tracer beads. Combined effect of the molecular diffusion and dispersion is evaluated and the Taylor dispersion coefficient is determined. Numerical simulations of suspension shear flow for test configurations relevant to plug dispersion were performed in order to present a new level of continuum models for particle stresses and particle fluxes in confined shear flows. These results can contribute to the design of high throughput microfluidic systems for cell screening and bio-separation.