This study presents a hybrid dumbbell-shaped micromixer designed, simulated, and geometrically optimized to achieve efficient mixing performance. The device leverages the synergy between electric field-induced flow and strategically arranged multi-scale circular barriers to disrupt laminar flow and significantly extend the influence of the applied electric field beyond the electrode region. This configuration enables sustained and robust mixing along the entire channel length. Comprehensive geometric optimization was performed on the channel width, length, and barrier radius. Additionally, parametric studies were carried out on inlet flow velocity, actuation frequency, and voltage to evaluate sensitivity and performance robustness. To assess mixing reliability, Mixing Index for all analyses was recorded at time points corresponding to the worst-case mixing scenario after stabilization, when localized concentration fluctuations persist at the outlet, resulting in peak nonuniformity. In this way, the micromixer consistently achieved a normalized Mixing Index above 0.98 across a broad frequency band of 6.5-15Hz and voltage window of 0.09-0.20V, indicating stable performance under varying excitation conditions. At 8Hz and 0.1V, as the operating point, the optimized configuration exhibited Mixing Index values between 0.987 and 0.994, corresponding respectively to the moments of maximum and minimum concentration nonuniformity at the outlet. This indicates consistent mixing performance, independent of the sampling time. Moreover, the device achieved near-complete homogenization in under 0.5 seconds, positioning it as a compelling solution for fast and reliable microfluidic applications.
Parisa Mahmoudi (Tue,) studied this question.