(482a) Analysis of Mixing in a Split-and-Recombined Multihelical Microchannel

In microfluidic systems, mixing is essential for many applications such as chemical and biological analyses. Due to the lack of turbulence at a low Reynolds number in conventional microfluidic systems, the mixing of fluids is poor and limited by molecular diffusion alone. While the most common approach to improving the mixing at the microscale includes active and passive methods that depend on increasing the interfacial area between the fluid streams, achieving efficient mixing is still an unmet need. It has recently been demonstrated that introducing curvature and torsion assisted secondary flow at the channel cross section facilitates the efficient mixing of fluid streams. However, these researches are only focused on three-dimensionally oriented fixed asymmetrical cross sections. Here, we present a novel split-and-recombined multihelical microfluidic mixer for efficient and ultra-fast mixing. The efficient and ultra-fast mixing is achieved by tailoring the split-and-recombination of multiple helical channels, helix radius, channel overlap, and axial length. In this regard, using COMSOL Multiphysics software, we have investigated the mixing of three separate fluid streams within a split-and-recombined multihelical microfluidic mixer as a function of split-and-recombination number, channel overlap, helix radius, axial length, and Reynolds number. A comparative study between three different types of geometries- Triple-straight (TS), multihelical (MH), and split-and-recombined multihelical (SRMH) channel is also done. Our findings demonstrate that at succeeding split-and-recombination points, the interface area between the fluid streams dramatically increases, resulting in effective mixing. In contrast to MH channels, where mixing efficiency increases with the Reynolds number, mixing efficiency in split-and-recombined multihelical (SRMH) channels does not significantly depend on the Reynolds number. This demonstrates that effective mixing may be accomplished at a lower flow rate or Reynolds number using a split-and-recombined multihelical (SRMH) channel.