Improvement of microchannel geometry subject to electrokinesis and dielectrophoresis using numerical simulations

Abstract

This paper addresses the effects of microchannel geometry with electrically insulating posts on a particle flow driven by electrokinesis and dielectrophoresis. An in-house numerical program is developed using a numerical model proposed in literature to predict particle flows in a microchannel with a circular post array. The numerical program is validated by comparing the results of the present study to those in the literature. Results obtained from a Monte-Carlo simulation confirm the three particle flow types driven by an external DC electric field: electrokinetic flow, streaming dielectrophoretic flow, and trapping dielectrophoretic flow. In addition, we study the effects of electrokinetic and dielectrophoretic forces on particle transports by introducing a ratio of lateral to longitudinal forces exerted on a particle. As a result, we propose an improved microchannel geometry to enhance particle transports across electrokinetic streamlines for a given power dissipation. The improved microchannel has a shorter longitudinal spacing between the circular posts than a reference microchannel. We also discuss the critical values of dimensionless variables that distinguish the three particle flow types for both improved and reference microchannels.