Introducing Novel Planar Micromixers with Pillars and Gaps and Studying the Impact of Various Geometric Parameters on the Efficiency of Micromixers

Chemical bioreactions play a significant role in many of the microfluidic devices, and their applications in biomedical science have seen substantial growth. Given that effective mixing is vital for initiating biochemical reactions in many applications, micromixers have become increasingly prevalent for high-throughput assays. In this study, numerical study is conducted to examine the fluid flow and mass transfer characteristics in novel micromixers featuring an array of pillars. The study explores the effects of pillar array design on mixing performance and pressure drop, drawing from principles such as contraction-expansion and split-recombine. Two configurations of pillar arrays are introduced, each undergoing investigation regarding parameters such as pillar diameter, gap size between pillar groups, distance between pillars, and vertical shift in pillar groups. Subsequently, optimal micromixers are identified, exhibiting mixing efficiency exceeding 99.7% at moderate Reynolds number (Re = 1), a level typically challenging for micromixers to attain high mixing efficiency. Notably, the pressure drop remains low at 1102 Pa. Furthermore, the variations in mixing index over time and across different positions along the channel are examined. Both configurations demonstrate short mixing lengths and times. The combination of rapid mixing, low pressure drop, and short mixing length positions the novel micromixers as highly promising for microfluidic applications.