(412a) Coarse-Grained Simulations of Trapping and Separation Using Microfluidic Flows and Fields

Many separation techniques rely on controlling the direction of transport and/or residence time of transport through a device. Separation can also be produced by selectively trapping some objects while not others. Many of these examples rely on preferential migration of objects across streamlines. Therefore, to design separations we must understand how that migration takes place. We have focused on situations in which the conformation of the object determines the migration. We have developed a coarse-grained Brownian dynamics simulation model that can quantify how the conformation changes in response to external fluid flows and electric fields, how the migration results from those changes, and the nonlinear coupling between the response and migration. In particular, we have examined how flexible polyelectrolytes stretch in velocity gradients and electric field gradients that alter their residence time. We have also examined rigid rods which can change their conformation by aligning the orientation of the rod axis. The ability of a rigid rod to resist compression leads to unique phenomena not seen in flexible objects.