Design of a Junction for a Noncontact Ultrasonic Transportation System

A junction for noncontact ultrasonic transportation paths in which small objects can be manipulated is proposed. The junction consists of a vibrating disc and a reflector. The reflector is installed parallel to the vibrator to generate an acoustic standing wave in the cavity between the vibrating disc and the reflector. The resonance modes of the acoustic field in the disc cavity between the two plates are calculated theoretically. The distributions of the sound pressure amplitude and the acoustic radiation force in air are calculated using finite element analysis. The flexural vibration modes with one nodal circle and four nodal lines at 45.4 kHz and two nodal circles and three nodal lines at 58.1 kHz are used to trap and eject small objects, respectively. The transportation velocity and the thrust force in the radial direction for a polystyrene particle with a diameter of 2 mm and a weight of 0.3 mg are 812 mm/s and 24 mu N, respectively. The ejection direction of the trapped object can be controlled by the driving condition of the vibrating disc.