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.

微型混合器是微流体处理和分析系统中的关键组件。对于生物样品的微混合，除混合质量外，作用于生物样品的水动力也非常重要。尽管已显示在微通道中增加刚性障碍物可改善混合性能，但它们会产生相当大的压降并在生物样本上施加很大的剪切力。为了解决这些问题，这里已经引入了可变形的挡板，作为用于控制混合特性的新型调节工具。为了优化设备性能（最大化混合性能和最小化压力损失），已采用两种优化算法来找出合适的挡板几何形状和材料特性。提出使用Taguchi方法作为一种快速，经济高效的方法来对混合指数或压降进行单目标优化，并引入了帕累托最优概念来对混合效率和压力损失进行并行优化。结果表明，用可变形挡板代替刚性板可显着降低压降（降低约50％），从而显着降低生物样品上的剪切应力，同时观察到混合效率略有降低（10％至15％）。