Ultrasonic propulsion of micro-particles is an attractive strategy for the remote manipulation of colloidal matter using biocompatible energy inputs. However, the physical mechanisms underlying acoustic propulsion are poorly understood, and our ability to transduce acoustic energy into different types of particle motions remains limited. Here, we demonstrate experimentally that gold microplates with twisted star shape can spin in a uniform acoustic field. We quantify the relationship between the particle shape and its rotational motion. The experimental observations are reproduced and explained by hydrodynamic simulations that describe the steady streaming flows and particle motions induced by ultrasonic actuation. These results suggest how particle shape can be used to design colloids capable of increasingly complex motions powered by ultrasound.
Mykola Tasinkevych / University of Lisbon
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