Acoustic dark lattices generated by composite spiral plates for multi-particle trapping

Abstract

The interactions of two Bessel acoustic vortices (BAVs) with different topological charges (TCs) have been investigated in detail. The theoretical results show that, with changing the TCs of two BAVs, the intensity distributions of the coupled-BAVs can switch among the petal mode, the acoustic dark lattice (ADL) mode, and the crescent mode, where the positions of the dark spots coincide with the phase singular points. We concentrate on the ADL modes and a composite spiral plate (CSP) is well designed to realize them. It is shown both numerically and experimentally that the CSP can create the ADL modes in air, which also exhibit strong self-healing. Additionally, the CSP is employed to generate ADLs in water. Four-order and six-order ADLs produced by two steel CSPs are used, respectively, to achieve multi-particle trappings in water experimentally. The capacity of the ADLs generated by the simple CSPs to trap multiple micro-particles in desired positions may find applications in biomedicine, including microarrays, tissue engineering, and regenerative medicine.