High‐performance micromixer design based on Cantor fractal principle: Numerical simulation

Abstract

As microfluidic chips emerge as a prominent and widely adopted technology, the multiple integrated units on the chip are progressively becoming the focal point of research. This paper investigates a T‐shaped passive micromixer based on the Cantor fractal principle. The mixing efficiency, concentration uniformity, and pressure drop are evaluated by considering baffle arrangement, fractal order, baffle height, baffle spacing, and Reynolds number. Firstly, comparison of symmetric and staggered Cantor baffles shows that the staggered structure enhances transverse splitting and recombination and therefore provides higher outlet mixing efficiency. For the two fractal orders examined in this work, namely primary and quadratic Cantor baffles, increasing the fractal order from primary to quadratic produces only a limited improvement in mixing efficiency; therefore, this conclusion should not be extrapolated to higher‐order Cantor structures without further verification. Increasing baffle height or decreasing baffle spacing enhances mixing but also increases pressure drop. Considering both mixing and hydraulic safety, the recommended geometric parameters are h  = 0.15 mm and d  = 0.1 mm. A quantitative performance metric, defined as the outlet mixing index divided by pressure drop, is added to evaluate the trade‐off between mixing enhancement and hydraulic penalty. At Re = 0.1 and 1, molecular diffusion and residence time dominate the mixing process, whereas at higher Re the baffles increasingly promote transverse advection and vortex‐assisted stretching. At Re = 100, the optimized micromixer achieves nearly complete outlet mixing in the numerical model.