Electroosmotic vortices-mediated active micromixer: Unveiling the performance of mixing quality

This work presents a micromixer with a diamond-shaped electroosmotic mixing chamber designed to improve fluid mixing at the microscale. The micromixer employs alternating current (AC) electroosmosis, facilitated by symmetrically positioned microelectrodes, which generate vortices that disturb laminar flow and promote enhanced convective mixing. The research examines how different operational parameters, such as average inlet velocity (U0), AC frequency (f), voltage amplitude (V0), and the inclination angle (α = 0°, 20°, 40°, and 60°) of the mixing chamber, affect mixing efficiency. The investigation is carried out systematically to analyze the performance of the mixing chamber at various inclination angles to maximize the mixing quality. A comprehensive numerical investigation is conducted to evaluate the influence of key parameters, including average inlet velocity (U0), AC frequency (f), voltage amplitude (V0), and the inclination angle of the mixing chamber (α). The governing equations for laminar flow, electric currents, and species transport are solved using the finite element-based solver. The results indicate that the diamond-shaped chamber geometry is critical in creating stable, symmetric vortices, which enhance the interaction between the two fluid streams. The optimal mixing performance is achieved at α = 20° with U0 = 0.05 mm/s, V0 = 0.5 V, and f = 8 Hz, reaching a maximum mixing quality of 98.47%, while maintaining a relatively low mixing cost of 0.001 485, under these conditions. Moreover, the study evaluates the relationship between mixing cost, mixing quality, and pressure drop, emphasizing how different inclination angles affect both. Pressure variation along the microchannel is also analyzed for different inclination angles, showing a trade-off between mixing quality and pressure drop. The findings highlight the potential of electrode-driven micromixers in achieving efficient mixing for low-Reynolds-number microfluidic systems, with potential applications in lab-on-a-chip devices and biochemical processes.