Electrokinetic particle migration in heterogeneous electrolyte systems

This paper presents a preliminary evaluation of an electrokinetic process for the buffer transfer and stacking of charged colloidal particles in solution. The mechanism exploits the effects of particle stacking across streamlines in a flow with electrical conductivity gradients transverse to the flow direction. Particle velocity fields and particle concentration measurements in a T-shaped microchannel system are presented. Upon application of an electric field, negatively charged particles are extracted from a low conductivity stream and stacked into a high conductivity stream. A simplified numerical model of the process with a commercial software code captures the generation of a transverse electric field.