Enhancing mixing performance in a circular-shaped electroosmotic micromixer through variable inner obstacle geometry

This study aims to enhance the mixing efficacy of distinct fluids within a circular-shaped alternating current (AC) electroosmotic micromixer featuring various central obstacle configurations. Four strategically positioned microelectrodes on the mixing chamber's exterior boundary perturb forced convection through AC electrokinetic effects. To achieve superior mixing quality (MQ), the circular, star, rectangular, and cross-shaped inner obstacles are explored under varying operational parameters, including Reynolds number (Re), oscillation frequency (f), voltage amplitude (V0), and Debye parameter (k). A mixing cost (MC) metric is evaluated to assess the energy efficiency relative to the achieved mixing quality. Numerical investigation revealed that the rectangular-shaped micromixer (ROMM) achieved maximum mixing quality of 98.92% at Re = 1 × 10−3, f*t* = 2, and V0* = 0.421 34. However, when considering both mixing quality and energy efficiency, the star-shaped micromixer (SOMM) emerged as the optimal configuration. This work provides valuable insights for the microfluidic device design, particularly Lab-on-a-chip (LOC) and Point-of-care testing (POCT) applications.