P6F-4 A Theoretical Time-Course Study of Acoustic Tweezers

Abstract

Single beam based optical tweezers has been applied to many biomedical applications in trapping macromolecules and cells. Due to the finite penetration ability of laser in tissue and only utilization in opaque particles, these limitations reduce the potential of optical tweezers in-vivo performance. Consequently, some researchers theoretically demonstrated to manipulate micro-size particles by acoustic tweezers to avoid mentioned problems. To allow particles trapping at desired positions in-vivo, the location of the trapping region is an essential issue for the acoustic tweezers. In this study, we propose a theoretical time-course model for acoustic tweezers to predict the particle spatial track versus time and furthermore to locate the particles trapping region. The theoretical model is based on the single beam focused acoustical field. Since the first radiation force from acoustic field is equal to the produce of the particle volume and the gradient of acoustical field, the spatial radiation force distribution can be obtained. A particle sustains force at a certain time can be calculated by summing entire the radiation force inside the particle. Given the particle mass, the acceleration of the particle can be obtained by means of Newton's laws of motion. To simplify the model, we assume the particle remains a constant acceleration within a very short time. By iteration method, the spatial track versus time of the particle can be predicted. The convergence of track represents the particle can be trapped by acoustic tweezers.