Acoustic trapping of particles using a Chinese taiji lens

Qinxin Zhou; Jing Zhang; Xuemei Ren; Zheng Xu; Xiaojun Liu

doi:10.1016/j.ultras.2020.106262

Acoustic trapping of particles using a Chinese taiji lens

Ultrasonics. 2021 Feb:110:106262. doi: 10.1016/j.ultras.2020.106262. Epub 2020 Sep 25.

Authors

Qinxin Zhou¹, Jing Zhang², Xuemei Ren¹, Zheng Xu³, Xiaojun Liu⁴

Affiliations

¹ Institute of Acoustics, Tongji University, Shanghai 200092, China.
² Beijing Institute of Electronic System Engineering, Beijing 100854, China.
³ Institute of Acoustics, Tongji University, Shanghai 200092, China; Jiangsu Key Laboratory of Opto-Electronic Technology, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China. Electronic address: gotoxvzheng@tongji.edu.cn.
⁴ Key Laboratory of Modern Acoustics, School of Physics, Nanjing University, Nanjing 210093, China. Electronic address: liuxiaojun@nju.edu.cn.

PMID: 33049475
DOI: 10.1016/j.ultras.2020.106262

Abstract

Focused acoustic vortex (FAV) beams can trap particles in a contactless and non-destructive way and the method has thereby attracted much attention. In contrast to the traditional complex and expensive transducer array, we propose a fast and cheap method to generate FAV beams in water using an ultrasonic holographic lens engraved with the Chinese taiji pattern. This method can obtain high transmission efficiency, and hence the strong trapping force makes the particles trapped stably in a straight line. The formation of the FAV beams derives from a superposition of the spiral phase of a Laguerre Gaussian beam and the focusing phase. Because of the phase singularity of this beam, the intensity of the ultrasonic field on the beam axis is zero, thereby forming a strong gradient surround the beam axis. The trapping and manipulation of polystyrene particles with a radius of 150 μm is realized in the gradient field of the FAV beam. The proposed single beam acoustic trapping method does not depend on the reflector, making it more suitable for the manipulation of cells in vivo.

Keywords: Chinese taiji; Focused acoustic vortex; Holographic lens; Particle trapping.