Microfluidic chaotic stirrer utilizing induced-charge electro-osmosis.
Recently, there has been a growing interest in using induced electro-osmosis to pump fluids in microfluidic devices. We show that induced electroosmosis can also be used to promote stirring and chaotic advection. To this end, we study theoretically a stirrer in which the flow patterns are alternated in time. We first analyze an idealized embodiment of the stirrer that admits a simple analytical solution for the flow patterns. The stirrer consists of a concentric annulus whose outer surface is defined by an array of electrodes that provide a spatially varying potential distribution. The resulting electric field induces quadruple electro-osmotic flow around the inner cylinder. By timewise alternating the potential distribution around the outer cylinder, we induce chaotic advection in the cavity. Subsequently, we carry out numerical simulations for a more realistic design that can be readily constructed, and demonstrate that it is possible to induce chaotic advection also in this case.
Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Hui
H
Zhao
Haim H
HH
Bau