Microcolumn formation between electrodes in a narrow channel from metallic colloidal suspension through induced-charge electrophoresis

Abstract

It is desirable to achieve the self-organization of a microcolumn between electrodes in a flow channel because the microcolumn can be used as a biosensor with high sensitivity. A direct simulation of a dispersed system of metallic particles in water is performed to show that a microcolumn between electrodes is formed by the application of an ac electric field. By the multiphysics coupled simulation technique between fluidics and electrostatics based on the boundary element method along with the double layer approximation, we find that microcolumns are formed by the growth of clusters perpendicular to the electrodes under the condition that the number density of particles is larger than the percolation threshold. Further, we propose a simple model that efficiently explains the time dependence of the probability of the formation of a microcolumn by considering standard collision theory and percolation theory. By this analysis, we can greatly contribute to developments in studies on the self-organization of microcolumns and biosensors.