Demonstration of inertial focusing in straight microfluidic channels with high reynolds numbers up to turbulence onset

Abstract

We report inertial focusing of 10 μm polystyrene particles in microfluidic channels with cross-section of 50×80 μm2 for channel Reynolds numbers (Rec) up to 2000. Thanks to our development of a high pressure-resistant microfluidic technology, we observed for 750<; Rec <;1500 at most 2 equilibrium positions of the focused streams, much closer to the channel center compared to classically observed equilibrium positions with Rec <;100. These inner equilibrium positions are in accordance with the previously observed inner-ring position [1] in millimeter-size tubes. The here reported inertial focusing with high Rec enables 10-to 20-fold higher throughput of focused particles than previously demonstrated.