Coarse grained simulations of migration of polyelectrolytes in a combination of flow fields and electric fields

Separations can be accomplished by controlling the relative rate at which different molecules travel through a microfluidic device. In a flow, the rate of travel of a molecule is largely determined by its relative position in the flow profile. Thus, if one can control molecules relative positions within a flow profile, one can influence separation. It has been found that the electrophoretic mobility of certain molecules, such as double-stranded DNA. is dependent on their conformation, which is in turn dependent on the local shear rate. This opens the door to using flow rate as a means to modify polymer conformation and by extension polymer mobility. Though this potential method opens the door to a variety of separations, there remain a number of fundamental questions about the underlying mechanism. To address these, we use a combination of theoretical calculations and Brownian dynamics simulations to probe how the combination of velocity gradients and electric field gradients impact particle mobility and migration.