Three-dimensional numerical study of induced-charge electrokinetic micromixing for non-Newtonian fluids with flexible conductive links

Efficient micromixing of biofluids and chemical agents remains a fundamental challenge in microfluidic systems, where low Reynolds number flows restrict mixing primarily to slow molecular diffusion. This study presents a comprehensive three-dimensional numerical investigation of an induced-charge electrokinetic (ICEK) micromixer incorporating novel flexible conductive links designed for non-Newtonian fluids. The electrically actuated flexible links function simultaneously as micro-stirrers and ICEK-driven vortex generators, producing enhancement of chaotic advection that significantly outperforms rigid-link and purely diffusion-driven designs. A coupled fluid–structure interaction model is solved in COMSOL Multiphysics and the systematic parametric analysis reveals that a three-link configuration with an opposite horizontal-plane orientation achieves a maximum mixing efficiency of ≈93 % for pseudoplastic fluids at an applied electric field of 200 V/cm. This represents a significant improvement over diffusion-only mixing, which achieves only ≈31 % efficiency. A conductive link length of 60 µm maximizes the swept perturbation region with acceptable flow restriction. Rheological analysis (n = 0.8 to 1.2) further demonstrates that pseudoplastic fluids generate stronger induced micro-vortices at lower electric field, resulting in superior mixing performance compared with dilatant fluids. Thermal analysis confirms that the maximum temperature rise remains below 10 K across all tested conditions, thereby maintaining compatibility with thermally sensitive biological samples.