A Numerical Investigation into the Influence of Electrode-Related Parameters on Electroosmotic Mixing and Related Mechanisms

Electroosmosis is an effective method for liquid mixing. It is associated with the motion of a liquid in a microchannel induced by an applied electric field. In this manuscript, a numerical model is elaborated and implemented for the case of a straight channel with a single electrode pair. In particular, the Navier-Stokes equation combined with the Convection-diffusion and Helmholtz-Smoluchowski equation are used to simulate the resulting flow field. The influence of various electrode parameters on the mixing efficiency and the related mechanisms are investigated. The numerical results show that a pair of eddies are produced alternately by the changing electric field. The two liquids are mixed by the interaction of this pair of eddies. The length of the electrode affects the distance between these eddies, while the amplitude and frequency of electrode voltage determine the intensity and frequency of the eddy current, respectively. It is shown that by tuning properly the electrode parameters, the mixing efficiency can reach 97.5%. The optimization process implemented in the present work may lead in the future to a new approach to obtain controllable electroosmotic flow in micro- fluidic platforms.