Simulation of Sinusoidal Symmetric Passive Microchannels for Blood Plasma Separation by CFD Technique

Microfluidic devices for efficient blood plasma separation are critical tools in medical diagnostics and disease research, enabling downstream analysis from minute samples. This study specifically investigated the enhancement of the cell-free layer (CFL), a key determinant of separation efficiency and plasma purity, within four novel passive microchannel geometries. These designs featured symmetrical sinusoidal expansions and contractions, leveraging secondary flows to manipulate red blood cell (RBC) trajectories. A rigorously validated Eulerian-Lagrangian multiphase Computational Fluid Dynamics (CFD) approach was employed to model the complex dynamics of RBCs suspended in plasma at physiological hematocrits. Simulations demonstrated that a targeted reduction in the minimum width of the sinusoidal contraction zone significantly enhanced CFL formation adjacent to the channel walls. Quantitatively, narrower throats produced a thicker and more stable CFL. Furthermore, this enhanced CFL development correlated strongly with a consequential increase in wall shear stress, localized specifically within the critical throat region. These findings, linking contraction geometry to CFL magnitude and stress profiles, clearly identify the geometric optimization of sinusoidal contraction features as a promising and effective strategy for designing next-generation, high-performance passive plasma separation microchannels, potentially improving yield for point-of-care devices.

Keywords:

microchannel , CFD Simulation , Eulerian-Lagrangian approach , Blood plasma separation , Cell-free layer (CFL)