Levich Institute Seminar Announcement, 02/07/2012
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Todd Squires
University of California, Santa Barbara
Department of Chemical Engineering
"Nonlinear Electrokinetics in Microfluidics"
I will discuss nonlinear, or induced-charge, electrokinetic flows, in which an applied electric field induces an ionic double-layer around a polarizable surface, then forces that induced ionic cloud (and the fluid around it) into motion. Such flows have seen increasing interest in the last decade for microfluidic systems -- for both fundamental and applied reasons -- but date back to Levich's pioneering work. From the standpoint of fundamental science, they are appealing because, in principle, all aspects (including the zeta potential) of these flows can be predicted from the standard theories of ion transport and fluid mechanics. Subsequent measurements, then, can be used to directly test the standard electrokinetic models. Measurements in our and other laboratories have shown significant discrepancies between theoretical predictions and experimental measurements. We will describe an experimental system we have developed that enables high-throughput measurements of ICEK flows over a wide variety of surfaces, and experiments we have developed with an eye to low-voltage, high-pressure microfluidic pumps. Our experimental motivated a series of theoretical problems to identify mechanisms that contribute to these discrepancies, which then motivated new experiments.
CURRENT RESEARCH INTERESTS:
Physicochemical Hydrodynamics, with a specific emphasis on electrokinetic effects in microfluidics; rheology of soft matter: active, nonlinear and interfacial