| Abstract
| - Electroosmotic flow in microfluidic systems is limited to the low Reynolds number regime. As a resultspecies mixing in electroosmotic flow systems is inherently diffusion dominated, requiring both a longmixing channel and retention time to attain a homogeneous solution. Recent studies have shown that theintroduction of oppositely charged surface heterogeneities to microchannel walls can result in regions oflocalized flow circulation within the bulk flow. In this study we seek to investigate these circulationregions, through 3D finite-element based numerical simulations, and then use them as a method of enhancingspecies mixing in a T-shaped micromixer. While all cases of surface heterogeneity are shown to enhancemixing efficiency, greater improvement is found when both the size of the heterogeneous region and thedegree of heterogeneity (i.e., the difference between the heterogeneous and homogeneous ζ-potentials) areincreased. In some cases the presence of heterogeneous regions is shown to reduce the required mixingchannel length by as much as 70%.
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