Noncontact Transportation of Planar Object in an Ultrasound Waveguide

This paper investigates acoustic levitation and noncontact transportation techniques for use with planar objects. An acoustic levitation system was developed which consists of a 1-mm-thick and 400-mm-long bending plate along with two bolt-clamped Langevin-type transducers (BLTs) that have stepped horns. A plane reflector was installed parallel to the vibrating plate to generate an ultrasound standing wave between the reflector and the plate. The sound pressure distribution in the ultrasound waveguide was calculated via finite-element analysis to investigate the effects of levitation of a planar object in the standing-wave field. A 1-mm-thick polystyrene plate was levitated along the nodal line of the acoustic standing wave in the waveguide. By controlling the driving phase difference between the two BLTs, the position at which flexural vibration occurs on the vibrating plate could be shifted along the length direction, and the trapped planar object could be moved by 9 mm along the same direction when the phase difference was varied from 0° to 360°.