In this study, the effects of zeta-potential, Debye-Huckel parameter and Reynolds number on electrokinetic mixing through heterogeneous microchannels are investigated. In previous studies, relatively complicated approaches were applied to examine the electrokinetically produced vortices; on the other hand, a relatively simple innovative micromixer consisted of a non-homogeneous rectangular microchannel with the prescribed arrangements of zeta-potential at the walls is considered in this paper. In other words, the mentioned microchannel has heterogeneous zeta-potential distribution at its wall, while other surface properties are assumed to be uniform and homogenous. Moreover, in order to investigate the mixing efficiency of microfluidic devices based on the electroosmotic flow is proposed. Actually, in the electroosmotic phenomenon, the fluid flow is caused by applying a potential across the microchannel. To achieve the electro-osmotic mixing, the Navier- Stokes, Nernst-Planck, Laplace and convection-diffusion equations are solved numerically for the velocity field, ions distribution, electrical potential, and concentration field, sequentially. Having examined the results, one can easily figure out that the performance of electro-osmotic micromixers intensively depends on the wall zeta-potential value and its distribution. Moreover, it can be inferred that the mixing efficiency is really dependent on Debye-Huckel or Reynolds number so that it will increase as soon as theses mentioned parameters decreases. One of the most important achievements of this paper is that a better mixing performance can be attained by the asymmetric charge pattern. In other words, it is really essential to arrange the charge pattern more asymmetric to achieve the highest mixing efficiency.

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