(475i) Inertial Microfluidic Sample Focusing for High Speed Flow Cytometry

Inertial microfluidics has recently been introduced as a high-throughput approach to particle and cell focusing with applications in sample filtration, enrichment and encapsulation. Inertial focusing occurs as the effect of hydrodynamic forces arising from interactions between particles and surfaces and other particles. Lift forces, shear gradient forces and Dean drag forces are predictable and controllable in microfluidic channels by geometric design to produce well-defined behavior. We demonstrate the application of inertial focusing to focus particulate and cellular samples for high-throughput flow cytometric analysis. Flow cytometry system miniaturization has been widely pursued, primarily through the integration of microscale optics and electronics, but has been hindered by a failure to replace hydrodynamic sheath focusing as the primary particle alignment method. We address this issue by creating a staged inertial focusing device that consists of straight and asymmetrically curved channels to passively produce a single stream of focused particles with three dimensional resolution. Longitudinal spacing of particles along the primary channel axis enable particularly precise particle analysis due to the elimination of coincidental events. The dynamics of inertial focusing in these channels will be described and the behavior of longitudinally spaced particle trains will be deconstructed. Finally, various applications for inertial focusing-enabled flow cytometry and application specific design considerations will be discussed.