Research On Ultrasonic Stage And Its Applications

This work is supported by the following funding organizations in china: National ScienceFoundation of China (No.91123020&No.51075212), NUAA (No.909386&56XZA12044), theInnovation and Entrepreneurship Program of Jiangsu. This project is finished in State Key Laboratoryof Mechanics and Control of Mechanical Structures(NUAA).Compared to other methods on the manipulation of micro and nano particles, the method ofpiezoelectric actuator has some advantages, such as the experimental setup is simple, the low spend etal.This paper focuses attention on an ultrasonic stage which can drive the micro particles rotation atthe stage center, form a circular spot of nanowires at the stage center and align nanowires on the stagesurface radially.In2008, Hu’s research group reported a method to rotate micro particles around a nodal point oftapered metal plate. First, this paper is focus on the analyses on the mechanisms of this phenomenonby FEM. The finite element analytical results showed that the driving mechanism is the travelingwaves around nodes which were caused by non-uniform vibrations at the root of wedged platestructure, and the number of valid nodes is closely related to the width of the wedged plate.Then, we proposed and developed an ultrasonic stage which can make different kinds of microparticles rotation at its center. The rotation direction of micro particles can be reversed by changingthe operating frequency of stage. The rotation speed can be controlled by operating frequency andvoltage of the stage. The rotation of micro particles is caused by travelling waves around the center ofthe stage.Finally, we report the use of a low-frequency circular ultrasonic stage to form a circular spot ofsilver nanowires (AgNWs) at the stage center and to align AgNWs on the stage surface radially. Themanipulations are implemented within a AgNW suspension droplet at the center of the ultrasonicstage. After the droplet dries out by natural evaporation without ultrasound, the spot and radialalignment have little change in the size and pattern. Principle analyses show that the spot formationand radial alignment of AgNWs are caused by the acoustic streaming in the radial direction in thedroplet.