Vortex generation and control in a microfluidic chamber with actuations

In this paper, we present a novel method for vortex generation and control in a resonator-shaped microfluidic chamber with actuations. By varying the actuation conditions, including the working transducers, frequency, and voltage, two regimes of vortices, clockwise vortex (CW vortex) and counter-clockwise vortex (CCW vortex), are generated in the chamber. We show that the direction of the vortex can be conveniently shifted from clockwise to counterclockwise by switching the working transducers without interrupting the flow, and the intensity of the vortex can be regulated by the actuation frequency and voltage. It is proposed that the vortex generation in the present case is due to the instability of the actuation-induced pulsatile flow through the sudden expansion part at the outlet of the chamber, while the vortex control is realized through the asymmetric flows in the chamber induced by the upper or lower transducers. The reported method of vortex generation and control can be applied in microfluidic operations for mixing enhancement of multiple reagents and distribution of microparticles and nanoparticles. Published by AIP Publishing.