Effects of obstacles on inertial focusing and separation in sinusoidal channels: An experimental and numerical study

Inertial microfluidics manipulates and separates microparticles based on the finite inertia of the fluid at high flow speed. In inertial microfluidics, modifying the geometry by embedding periodic micro-obstacles into curvilinear channels is emerging as a promising strategy to improve inertial focusing and separation. This work systematically investigated the influence of micro-obstacles on inertial focusing and developed a high-resolution microfluidic device for particle and cell separation. First, we developed numerical modelling to simulate the migration trajectories of particles. Then, we studied the effects of various obstacles on the inertial focusing in the sinusoidal channels. The concave obstacles were more effective in tuning particle inertial focusing and separation than convex obstacles. Furthermore, the square concave obstacle channel could offer the highest separation resolution. Finally, we developed a microfluidic device based on square concave obstacle channel, and applied it for the high-efficiency separation of polystyrene beads and U87MG cancer cells from the blood.