A novel design for split-and-recombine micromixer with double-layer Y-shaped mixing units

A novel split-and-recombine (SAR) micromixer with Y-shaped mixing units is proposed. The two sets of Y-shaped units are distributed periodically and in opposite directions. The micromixer has better mixing performance and smaller pressure loss due to the three-dimensional Y-shaped structure, splitting recombination, and chaotic convection mechanism. First, based on the finite element theory, with the mixing index and pressure loss as the objective function, the software COMSOL was used to simulate and analyze the structure parameters and performance of the micromixer. Then, a prototype was manufactured, and experimental platforms were set up in the lab. Finally, the color reaction and silver nanoparticle synthesis experiments were carried out to characterize and verify that the micromixer is feasible. Simulation and experimental results show that, as an important structural parameter of the micromixer, the channel aspect ratio φ has a great impact on its mixing performance and pressure loss. When the aspect ratio φ = 0.5, the micromixer has excellent overall performance; With the increase of the Reynolds number (Re =0.5–100), the mixing index tends to decrease and then increase, while the pressure loss gradually increases. It has a mixing index of 0.966 at Re = 5, and the mixing index reaches 0.9992 at Re = 100. The pressure loss ∆P is less than 350 Pa through seven Y-shaped units at Re = 100; The micromixer enables to obtain uniform and efficient color reactions and to synthesize silver nanoparticles with good size, morphology, and monodispersity. The micromixer has broad application prospects in chemical synthesis, biochemical analysis, and biomedicine.