Performance evaluation of a 3D split-and-recombination micromixer with asymmetric structures

Abstract Micromixers are widely used in lab-on-a-chip devices for analytical chemistry, bioengineering, and biomedicine to achieve rapid mixing and analysis of samples. However, the existing micromixers are mostly two-dimensional structures with low mixing efficiency. Even three-dimensional (3D) micromixers with complex structures have low mixing efficiency in the low Reynolds number range. In this paper, a 3D split-and-recombination (SAR) micromixer inspired by the horseshoe transform principle is proposed to further improve the mixing efficiency. There 3D SAR micromixers with different subchannel sizes were designed and tested in the Reynolds numbers range of 0.1–100. The optimal size of the micromixer was revealed through computational fluid dynamics simulations and experimental test results. A minimum mixing index of 91% is achieved in the range of Reynolds numbers from 0.1 to 100. Especially, for Re ⩾ 20, the mixing index is higher than 99%. The results obtained indicate that this 3D SAR micromixer with an asymmetric structure shows a satisfactory choice in the fluid mixing process of microfluidic systems, and has a potential application in the field of microchip-based biochemical analysis.