Performance optimization of a novel passive T-shaped micromixer with deformable baffles

Abstract

Micromixers are critical components within microfluidic fluid handling and analysis systems. When it comes to micromixing of biological samples, the hydrodynamical forces acting on biological specimens are of great importance besides mixing quality. Although adding rigid obstacles to the microchannels has shown to improve the mixing performance, they create a considerable pressure drop and impose a significant shear force on biological specimens. To address these problems, deformable baffles have been introduced here as a novel tuning tool for controlling the mixing characteristics. To optimize the device performance (maximizing the mixing performance and minimizing the pressure loss), two optimization algorithms have been employed to find out the suitable baffle geometry and material property. The Taguchi method was proposed as a fast and cost-effective approach for single-objective optimization of the mixing index or the pressure drop, and the Pareto optimality concept was introduced for parallel optimization of the mixing efficiency and the pressure loss. The results show that replacing the rigid with deformable baffles significantly reduces the pressure drop (by approximately 50%), causing a significant reduction in the shear stress on biological samples while a small reduction on the mixing efficiency (10 to 15%) was observed.