Fluid mixing efficiency enhancement in microchannels having spiral elliptic and curved structures with various baffle geometries

Official URL: https://risc01.sabanciuniv.edu/record=b2553617 _(Table of contents)

Passive micromixers have attracted much attention during recent years due to the low-cost and simple fabrication procedures with less power input in their implementation to high-throughput microfluidics platforms. Increasing the efficiency of micromixers could be possible with an optimum geometry of inertial microfluidic channels, which utilize Dean vortices and Dean flows for the enhancement of mixing. Recently, micromixers with curved microchannels have been introduced to the literature. Yet, the enormous potential of elliptic spiral and baffled embedded curved serpentine microchannels has not been adequately revealed. This study aims to assess the mixing performance of polydimethylsiloxane micromixers having five-loop spiral microchannels with elliptic configurations and serpentine microchannels with a curvature angle of 280°. The elliptic spiral micromixers have different initial aspect ratios with a varying radius of curvature along the channel whereas the serpentine micromixers with a fixed radius of curvature consist of six different baffle configurations embedded into the side walls to investigate the effect of the number and geometry of baffles on mixing efficiency. The performances of these micromixers were evaluated by comparing the mixing indices obtained from inverted fluorescence microscopy over Reynolds numbers ranging from 10 to 100 and 1 to 50 for elliptic spiral and serpentine micromixers, respectively. The development of transverse Dean flows and Dean vortices within the micromixers with elliptic spiral microchannels could provide mixing indices up to 96% at a low Reynolds number (Re=40) while the maximum outlet mixing indices of serpentine micromixers with quasi-rectangular baffles was 98% at a Reynolds number of 20