Dispersion due to electroosmotic flow in a circular microchannel with slowly varying wall potential and hydrodynamic slippage

Abstract

An analysis using the lubrication approximation is performed for the dispersion of a neutral non-reacting solute due to electro-osmotic flow through a circular channel under the combined effects of longitudinal non-uniformity of potential and hydrodynamic slippage on the channel wall. The wall is periodically patterned for the charge and slip distributions, with a wavelength much longer than the channel radius. It is shown that the presence of slip can greatly amplify the increased dispersion caused by induced pressure gradient brought about by the non-uniformity of wall potential. Non-uniform wall potential interacting with non-uniform slip can give rise to effects much different from those when the potential and slip are both uniformly distributed and equal to the averages of the non-uniform distributions. Mobility and dispersion associated with recirculating flow resulting from oppositely charged slipping region is also examined.