Numerical study on AC electroosmosis in microfluidic channels

This paper deals with parametrical studies focused on determination of selected characteristics of AC electroosmotic micropumps in non-linear (high-amplitude) regimes in the interdigitated arrangement. The net velocity and current-voltage phase shift are computed. Non-equilibrium Navier-Stokes-Poisson-Nernst-Planck model that describes the transport processes in the entire time and spatial domains including electric double layers (EDLs) was derived and analyzed. The obtained results were qualitatively interpreted by means of a simple relation derived for RE circuit in series. Locations of the high net velocity regions in the parametric space were found. The model thus can contribute to development and optimization of microfluidic devices driven by AC electric fields. Flow reversals were observed in frequency and geometric scale characteristics. We suggest that the flow reversals do not necessarily rely on the electric charge injection or the condensed layer formation. The direction of the net flow probably depends only on an interplay of the electric, viscous and pressure forces. (C) 2009 Elsevier B.V. All rights reserved.