A study of levitation principle in ultrasonic levitation

Abstract

Ultrasonic levitation is technology that can levitate small objects with ultrasonic. In this technology, levitated objects do not have any material restrictions, and not only a solid substance but also liquid substance can be levitated. Therefore, this technology is expected to have various industrial applications, for instance, drop mixing experiment and material experiment in zero gravity. Although there are some methods of ultrasonic levitation, in this study, we use method of using Langevin-type transducer. This method is simple and inexpensive, consequently we can easily apply it to industrial use. This paper describes consideration of levitation principle according to the theory of acoustic radiation force on spheres suggested by L.V.King. In particular, we calculated acoustic radiation force and natural frequency of levitation object when it vibrates freely, using actual specifications. In order to verify the theory of King, we compared the theoretical value of natural frequency with the experimental value of it. Furthermore, we calculated two-dimensional sound pressure distribution in the sound field to determine where levitated objects will be trapped.