Acoustic Trap Step for Single-Axis Acoustic Levitators

Abstract

Acoustic manipulation is extensively employed due to its versatility and noncontact capability. Although significant developments have been made in this field, the dynamic process of the acoustic trap position in the manipulation of acoustically levitated objects has not been fully investigated, hindering the development of acoustic manipulation technology. Herein, we propose the gravity-acoustic trap morphology ($G$-ATM) method to elucidate the dynamic process in single-axis levitators. First, the acoustic trap step is defined to describe the dynamic process. Then, based on the $G$-ATM method, the study is carried out for single-axis levitators from the radial and axial points of view. In the radial direction, the stage concept is proposed to explain the impact of gravity, the impact of acoustic trap morphology is expressed by radial acoustic radiation force distribution, and transitional levitation states are observed and explained. In the axial direction, the impact of gravity is analyzed from the kinetic energy perspective, the impact of acoustic trap morphology is presented by multiple adjacent acoustic traps, and the principle of proximity followed by the motion of levitated objects is proposed. Finally, all analysis results are verified by simulations and experiments. The work will help to improve the rapidity and stability of acoustic manipulation and promote the development of acoustic manipulation technology.