3D Finite Element Modelling of Mixing Phenomena in Droplet-based Microfluidic Systems

This study characterizes the mixing processes within microscale confinements in three-phase microfluidic systems designed for droplet generation. Finite Element Modeling (FEM) was employed to analyze droplet formation and mixing efficiency using the Laminar Flow, Ternary Phase Field, and Transport of Diluted Species modules in COMSOL Multiphysics. The numerical simulations revealed that specific microfluidic channel designs significantly impact mixing efficiency within droplets. A serpentine channel architecture enhanced mixing efficiency by up to 15% compared to a straight channel design. In curved channels, Dean instability created vortices, significantly enhancing mixing within droplets. Varying flow rates also affected the mixing process: initial flow rates of 0.2 µl/s for water, 0.2 µl/s for BSA solution, and 0.02 µl/s for oil (1:20 ratio) resulted in steady phase distributions with limited mixing, while adjusted flow rates of 0.2 µl/s for water, 0.2 µl/s for BSA solution, and 1.4 µl/s for oil (3.5:1 ratio) induced a droplet generation regime, enhancing mixing efficiency. Optimized channel designs and flow rates are crucial for achieving homogeneous environments in microdroplets, essential for individual cellular and molecular studies.