主辅通道型微混合器的设计与制作

Design and fabrication of micromixer with main-assist channels

为了实现微量液体的快速均匀混合,设计了一种PDMS双层结构的新型微混合器。研究了混合器的制作方法以及几何尺寸和Re数对混合的影响。依据Fick第一定律介绍了主辅通道型微混合器的设计原理;采用有限元方法对不同几何尺寸及Re数下混合器中液体的速度流场及浓度场进行了数值模拟;数值分析显示,随着主辅通道出口宽度比的减小,通道长度的增加和雷诺数的减小,混合器的混合率增加。最后,依据仿真结果制作了主辅通道深度比为0.71,出口宽度比为1,通道长度为9mm的微混合器并进行了去离子水和红墨水的混合实验。实验结果表明:当Re<5时,设计的混合器能实现液体的快速混合,并且混合率随着Re的减小而增大,基本满足低Re数下微量液体快速均匀混合的要求。

A double-layer micromixer made from Polydimethylsiloxanes（PDMS） was designed to realize uniform mixing for microlitre liquids.Its fabrication methods and the effects of geometrical sizes and Reynolds numbers（Re） on it were investigated.The design principles of the micromixer with main-assist channels were presented based on Fick’s first law and the velocity and concentration distribution of the micromixer in different geometrical sizes and Re were simulated by finite element method.The calculated results demonstrate that the mixing efficiency increases with the decreases of Re and width ratio and the increase of channel length.Then a mixer with a channel length of 9 mm,depth ratio of 0.71 and a width ratio of 1 was fabricated.The results of mixing experiments of water and red ink show that the micromixer designed at Re5 can realize the fast mixture of two streams and the efficiency of mixture increases with the decrease of Re.It can meet the requirements of micro fluid’s rapid mixing at low Re.