A novel passive micromixer with trapezoidal blades for high mixing efficiency at low Reynolds number flow

In this paper, we propose a novel passive micromixer structure based on the effect of stretching-folding in both vertical and horizontal directions. The channel depth of the micromixer is tightened at two ends each mixing unit. The fluid flows are repeatedly twisted and bent from left to right and vice versa. With this special structure, our proposed micromixer can create vortices and transversal flow even at low Reynolds number. Therefore, it can efficiently mix low speed liquid flows, making it easy to be built into micro-devices. We conduct intensive simulation to evaluate the performance of our proposed mixer by using COMSOL Multiphysics package with Navier-Stokes, convection-diffusion equation and particle tracking method. The simulation results demonstrated that our micromixer may be the first device that is able to operate with high mixing efficiency independent of the Reynolds number in the range of 0.5 to 60. Especially, at very low Reynolds number the mixing efficiency of our proposed micromixer is 220-240% higher compared with those of rhombic mixer with branch channels and pure rhombic mixer.