(142c) Acoustic Propulsion of Bubble-Engined Microswimmers

We elucidate the theoretical aspects of locomotion for the recently developed acoustically-powered microswimmers. Through bubbles, such a swimmer harvests acoustic energy supplied through the environment from a piezoelectric transducer. Although the motion of the swimmer is at low Reynolds number, the engines works at relatively high Reynolds number such that the reciprocal dynamics does not fall within the paradigm of scallop theorem. The simmers acquire their highest speed at bubble's resonance frequencies, providing a firm ground for selectively actuating, separating or even steering toward a target simply by changing the ultrasound frequency. Since ultrasonic techniques have been employed successfully in medical applications, such acoustic-powered microswimmer, if made with biocompatible and biodegradable polymers, can promise applications that can address drug delivery and non-invasive surgery.