Abstract
Manipulating small particles is an important issue in the scientific area. The optical tweezers provide a good tool for capturing the small particles. Many studies were accomplished by the optical tweezers. Due to the physical limitations of the laser, the application of the optical tweezers in the deeper material is impossible. Acoustic tweezers are motivated by the sound wave. Sound wave can propagate in the non-vacuum medium with higher efficiency than the electromagnetic wave does. Previous studies of acoustic tweezers were based on the structure of using dual-transducer mode with standing wave to capture small particles. However, such experimental structure limited the applications. In this thesis, we are going to propose a new method with a single-element transducer to capture the small particles by a pulsed-mode sound wave. In this study, the force analysis exerted on the small particles in the pulse-mode and time-course acoustics fields would be discussed first. Based on the force distribution results obtained from the acoustic field, the motion of the particle can be calculated by the iteration method. The tract of the small particle can be an index to be determined the particle was trapped by the acoustic field or not. The first condition was set that the particle was located at the central z-axis. The results were only considered the force for the central z-axis. The simulation parameters were including transducer f-number, particles acoustic impedance and their radius. From the results, the small f-number transducer, particles with water-like acoustic impedance and larger sizes would be the best conditions for the trapping of acoustic tweezers. In addition, the cases of the particles no longer located at the central z-axis were also considered. The results demonstrate very similar conclusions of those in one-dimension cases. Finally, the feasibility of pulse-mode acoustic tweezers was discussed. Potential application of the technique is to control the small particles such as drugs in the human or animals’ studies.