Inertial separation of particles with small size-variation using self-releasing microvortex

This work presents an inertial microfluidic device for continuous size-based separation of microparticles with down to <;2μm size-difference. The design uses a high-aspect-ratio microchannel to inertially equilibrate particles into two bands along side walls. The microchannel expands downstream to form two symmetric chambers in which laminar microvortices are generated for cell extraction. A side outlet in each chamber continuously extracts larger cells, while the smaller cells exit through the main central outlet. The design offers a number of advantages, including simplicity, small footprint, one-step operation, and continuous separation with ultra-selectivity. Separation of 21μm from 18.5μm particles with high purity (79%) was demonstrated, suggesting utility in particle or cellular sample preparation with precise size-control.