Robust acoustic pulling using chiral surface waves

TL;DR

This paper demonstrates a novel method for long-range, robust acoustic pulling using chiral surface waves on phononic crystals, overcoming limitations of traditional methods and enabling flexible particle manipulation.

Contribution

It introduces a new acoustic pulling scheme based on chiral surface waves supported by spinning cylinders, leveraging topological acoustics for enhanced robustness and flexibility.

Findings

Achieves long-range acoustic pulling with backscattering immunity.

Enables flexible particle trajectories independent of particle properties.

Overcomes limitations of traditional structured beam methods.

Abstract

We show that long-range and robust acoustic pulling can be achieved by using a pair of one-way chiral surface waves supported on the interface between two phononic crystals composed of spinning cylinders with equal but opposite spinning velocities embedded in water. When the chiral surface mode with a relative small Bloch wave vector is excited, the particle located in the interface waveguide will scatter the excited surface mode to another chiral surface mode with a greater Bloch wave vector, resulting in an acoustic pulling force, irrespective of the size and material of the particle. Thanks to the backscattering immunity of the chiral surface waves against local disorders, the particle can be pulled following a flexible trajectory as determined by the shape of the interface. As such, this new acoustic pulling scheme overcomes some of the limitations of the traditional acoustic pulling using structured beams, such as short pulling distances, straight-line type pulling and strong dependence on the scattering properties of the particle. Our work may also inspire the application of topological acoustics to acoustic manipulations.