Study of the Effect of AC Electric Potential Applied on Co-planar Microelectrode Array on Electroosmotic Flow in a Slit Microchannel

Abstract

Under the influence of an AC electric field, electrolytes on a planar microelectrodes exhibit steady fluid flow, termed as AC electroosmosis. A numerical model using finite element method has been developed to solve the electrokinetic flow parameters of the AC electroosmosis in a slit microchannel. A thin-layer, low-frequency, nonlinear analysis of the system is performed including Faradaic currents from electrochemical reactions at the electrodes. The non equilibrium model consists of Navier-Stokes, continuity, Nernst–Planck and Poisson equations. In the first step, transient simulations are carried out to obtain a homogeneous steady state stable periodic regime. The obtained stable period solutions are then analyzed to compute the time averaged net velocity and other characteristics of the AC electroosmotic flow. Net flow velocity and flow rate are observed for different geometric parameters, electric field parameters, electrode position, Debye length and effective thickness. Dependency of different parameters on the frequency of AC signal is analyzed for optimal design of AC electroosmotic micropump. Such mechanism can be used to transport, mix, separate, and manipulate various molecular or colloidal entities e.g. DNA, protein, polymers etc. in microfluidic chips.