Experimental validation of induced-charge electrokinetic motion of electrically conducting particles

Abstract

A key characteristic in the theory of the induced charge electrokinetic flow is the vortices generated by the interaction of the applied electric field with the induced dipolar electric double layers around an electrically conducting surface. The vortices can significantly influence the electrokinetic motion of a particle with an electrically conducting surface. This paper provides the visual evidence of the vortices in the induced charge electrokinetic flow in a “DC field” around a metal surface that is “not an active electrode”. According to authors’ knowledge, this is the first experimental proof of induced-charge electrokinetic phenomena for DC electric field while all the literatures employed the AC field as the acting force during the experiments. Moreover, former studies had mostly reported the vortices around active electrode, used as a conducting surface. Current paper reports the induced vortices around a non-electrode conducting surface. In addition, the experimental results of this paper show that the measured velocity of the electrokinetic motion of particles with a metal hemisphere in a microchannel is much higher than that of the non-conducting polymer particles of the same size under the electric field. These experimental data agree well with the theoretical prediction.