Design and analysis of the cross-linked dual helical micromixer for rapid mixing at low Reynolds numbers

We demonstrated rapid and stable fluid micromixing at low Reynolds numbers in an easily fabricated and geometrically simple three-dimensional cross-linked dual helical (CLDH) micromixer. Mixing mechanism of the CLDH channels was investigated with numerical simulations. The split and recombine (SAR), chaotic advection, and flow impact mixing effects were integrated and improved in the passive mixer with CLDH channels. A new SAR mixing effect dominated by flow collision was involved in the mixer in which a cycle of CLDH mixer can achieve two SAR mixing courses which is more effective than conventional SAR mixers. A geometric optimization method of studying the mass flow rate of flow streams was proposed to obtain the optimized structure, which can be applied to optimizing passive mixers with crossed or overlapped channels. The CLDH mixer shows a stable and excellent mixing capability in an extra short length for a wide low Re range; 99 % mixing degree can be achieved in four cycles (i.e., 320 μm) for 0.003 < Re < 30. This rapid and robust micromixer will contribute to a flexible application in microfluidic systems.