Superior mixing efficiency in inertial sunflower microfluidics

Micromixing has emerged as a promising approach due to its advantages, including accelerated mixing times, reduced sample volumes, and cost-effectiveness. In biological applications, where intricate living systems are studied, the degree of mixing, signifying the homogeneity of the mixture, assumes paramount importance. Micromixers, integral components of MEMS (Micro-Electro-Mechanical Systems), harness microscale mechanical and electro-mechanical elements to achieve efficient mixing. These micromixers are broadly classified into passive and active categories based on the presence of external driving forces. Passive micromixers exploit inertial forces arising from geometric channel configurations to induce mixing. The efficacy of passive micromixers is assessed based on the mixing index, a critical parameter central to this investigation that quantifies the extent of intermixing between two fluids. This study explores Sunflower geometry as a passive micromixer by mixing simulations conducted at 10 ≤ Re ≤ 100 and experiments conducted at 10 ≤ Re ≤ 60, aiming to understand how the performance of the Sunflower geometry changes. Sunflower geometry was examined through comparisons with spiral micromixers to assess the extent of its distinctiveness. The study’s findings demonstrated how well-suited sunflower micromixers are for producing complete mixing. In particular, the sunflower micromixer outperformed the spiral micromixer, producing a noteworthy 99% mixing ratio at its exit when tested under a flow with a Reynolds number of 100 in the simulation analysis. Similarly, experimental analysis at Re 60 reveals a ⁓99% mixing ratio even at a shorter distance. Analysis of simulated and experimental data also revealed a strong correlation between mixing quality and higher Reynolds numbers.