Electrokinetically driven reversible banding of colloidal particles near the wall

Abstract

Polystyrene microparticles of 0.5 μm diameter form long-lived streamwise bands within 1 μm of the wall in the combined steady electroosmotic (EO) and Poiseuille flow of a dilute particle suspension through fused-silica microchannels. The bands disappear when the electric field driving the EO flow is turned off, and the band characteristics can be changed by adjusting the flow parameters. To our knowledge, these are the first observations of near-wall particle self-assembly due to shear and steady electric fields.