Particle handling in straight microfluidic channels via opposing electroosmotic and pressure-driven flows

The current study presents a method for producing recirculation zones in a straight microchannel using opposing pressure-driven and electrokinetically driven flows. The interaction of these two flow streams causes flow recirculation structures, which restricts the flow passage within the microchannel and causes a nozzle-like effect, thereby increasing the separation distance between particles in the fluid stream. Theoretical and experimental investigations are performed to investigate the effects of the applied electrical field intensity on the flow recirculation size, and the nozzle-like effect, respectively. In general, the results confirm that the proposed approach provides an effective means of achieving particle acceleration and separation distance within straight microchannels, and therefore provides a viable technique for improving particle manipulation and optical detection in conventional microfluidic devices.