A three-dimensional double-helical structure microfluidic chip with efficient mixing

In recent years, the mechanism based on changing the cross-sectional shape of long and straight channels for increasing mixing efficiency has reached a bottleneck, while the vortex effect brought by curved channels has become a hot topic in current mixer research. The vortex effect should be fully utilized in the mixing process. Inspired by the spiral structure as well as splitting and reorganization, a passive three-dimensional double-helical structure micro-mixer was proposed. It is printed by FDM (fused deposition) technology. First, a model of the double-helix structure was printed with HIPS (high impact polystyrene) material, which was supported by PVA (polyvinyl alcohol) material. The mixing experiments showed that the three-dimensional (3D) double-helix structure could increase the mixing efficiency to 90.6%, while the mixing efficiency of the conventional two-dimensional (2D) T-shaped structure was only 78.5%. In this paper, the effects of the number of turns, pitch, diameter, staggering angle, and flow rate on the mixing effect are compared separately. The results show that the change of staggering angle has a better effect on the improvement of mixing efficiency.