Induced-Charge Electro-osmosis

Prof. Martin Z. Bazant
Associate Professor of Applied Mathematics
Institute of Soldier Nanotechnologies
Massachusetts Institute of Technology

Abstract
"Induced-charge electro-osmosis" (ICEO) refers to the nonlinear slip of a liquid electrolyte at a polarizable (metal or dielectric) surface when an electric field acts on its own induced double-layer charge. "Induced-charge electrophoresis" (ICEP) refers to motion of a polarizable particle due to ICEO flow with broken symmetry. In this talk, we present the basic theory of ICEO and ICEP, as well as (subsequent) experiments demonstrating ICEO flows in microfluidic devices and ICEP motion in colloids. Current engineering applications in our lab include three-dimensional electrokinetic pumps, which outperform planar AC electro-osmotic pumps by an order of magnitude (e.g. mm/sec flow at 1 Volt kHz AC) and thus enable portable lab-on-a-chip technology. Such devices typically place "large" voltages (>> kT/e) across the double layer, so we are extending the theory of ICEO to account for steric and viscoelectric effects at highly charged surfaces. This is a first step toward understanding how solution chemistry affects nonlinear electrokinetics.

For more information, see http://math.mit.edu/~bazant/ICEO.

Thursday, April 27, 2006
2 PM, 337 Towne Bldg.