Actuation force characteristics of ultrasonic suspension for minute object

In near-field levitation, an object can be levitated vertically upward above vibrating surface of an ultrasonic transducer. On the other hand, it has been reported that an object can be suspended vertically downward under the vibrating surface in the air. We call this phenomenon ultrasonic suspension. When an object is suspended, there is restoring force, which attracts the object to the center of the vibrating surface. By using ultrasonic suspension in handling minute objects, we have some merits such as non-contact, easy release, material independence, possibility to approach above the object and so on. Actuation force of the ultrasonic suspension, however, has not been investigated precisely yet. Therefore, in this research, characteristics of the forces acting vertically and horizontally were investigated experimentally. A servo type measuring mechanism was composed to measure vertical and horizontal direction forces simultaneously. This paper reports fabrication of the measuring mechanism and actuation force characteristics based on measurement results.