Investigating the influence of induced charge and surface charge heterogeneity on electrokinetic micromixing: A comparative analysis

Abstract

This paper investigates the performance of a micromixer by considering the combined effects of surface charge heterogeneity and the induced charge electrokinetic (ICEK) phenomenon. With the applied electric field, surface charge heterogeneity generates a recirculation zone within the microchannel, while conductive links induce micro-vortices. The main objective is to explore the influence of various control parameters on the mixing efficiency, including zeta potential, the number and orientation of conductive links, and applied electrical potential. The generated recirculation zone and induced micro vortices introduce chaotic perturbations within the microchannel, improving mixing performance. The results demonstrate that increasing the zeta potential on heterogeneously charged patches enhances the mixing performance, albeit at the expense of a reduced average outlet velocity. Additionally, a higher number of conductive links leads to increased mixing efficiency. The combination of mounting a conductive link inside the channel and applying a heterogeneous zeta potential patch on the wall substantially increased mixing efficiency. The influence of fluid rheology on mixing performance is also investigated, revealing that pseudoplastic fluids exhibit better mixing than dilatant fluids. Finally, the combined effects of all parameters are evaluated using the Taguchi method, resulting in an optimized mixing performance for the proposed micromixer. Micromixing efficiency exceeding 98% is achieved for all types of non-Newtonian fluids under optimal parametric conditions.