Experimental and numerical acoustofluidics in bulk acoustic wave devices at ETH Zurich

Abstract

Ultrasonic fluid cavity resonances in acoustofluidic micro-devices can be exploited to miniaturize important operations for the handling of beads, cells, droplets, and other particles. With a growing number of experimentally tested unit operations, acoustofluidics holds increasing promise for emerging applications in bio- and microtechnology on lab-on-a-chip systems. We provide an overview of our research activities during the last years with a focus on the latest experimental setups and advances in the numerical simulation. Specifically, we present micro-devices with impedance matched cavity walls that allow a more flexible device design. Further, we show devices for the handling of fluid droplets and report on a method for the direct measurement of the acoustic radiation force on micro-particles. Due to the rapidly growing computational capabilities, numerical simulation has become a valuable tool in acoustofluidics research. We present a numerical model that accurately mimics the boundary layer damping inside the fluid cavity, allowing to make predictions of the attainable acoustic amplitudes and radiation forces. Furthermore, we demonstrate how numerical optimization of the device geometry is used to design new devices in an automatic fashion. Finally, we show how the radiation forces and torques can be deduced from the simulated acoustic fields to compute trajectories of complex shaped particles.