Martin Z. Bazant
Associate Professor of Applied Mathematics
Department of Mathematics
Massachusetts Institute of Technology
Cambridge, Massachusetts
The dynamics of electrolytes is usually described by circuit models, where the double layer is an impedance in series with a bulk resistance. When diffuse-charge dynamics has been considered, the classical theory (Poisson-Nernst-Planck equations, Smoluchowski slip formula,...) has been almost invariably used, which assumes a dilute solution of point-like ions interacting through a mean field in a uniform dielectric continuum. In many situations of current technological interest, however, such as induced-charge electro-osmotic flows in microfluidics, charging of supercapacitors, or impedance measurements in micro-biosensors, electrolytes are subject to "large" voltages (>> kT/e = 25 mV) where the classical theory breaks down, due to crowding of ions near a surface. This talk presents some general consequences of steric and viscoelectric effects in double-layer charging and ICEO flow, compared to experimental data in microfluidic devices. .
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