Acoustic levitation is a method for suspending matter in a medium by using acoustic radiation pressure from intense sound waves in the medium. It’s possible because of the non-linear effects of intense sound waves. Lately, a team of Japanese scientists from the University of Tokyo and the Nagoya Institute of Technology, has successfully levitated and moved objects using ultrasound waves.
Acoustic levitation is usually used for containerless processing which has become more important of late due to the small size and resistance of microchips and other such things in industry. This method is harder to control than other methods of containerless processing such as electromagnetic levitation, but has the advantage of being able to levitate nonconducting materials. However, there’s no known theoretical limit to what acoustic levitation can lift given enough vibratory sound, but since long time scientists have kept themselves busy in discovering the answer.
On the other side, earlier researchers levitated and moved objects using ultrasound waves, but in a two-dimensional space. But this time, some Japanese scientists have successfully levitated and moved objects in a three-dimensional space through a complex system of acoustic levitation using ultrasound waves. In order to move expanded polystyrene particles of 0.6 mm and 2 mm in diameter, the Japanese scientists placed the objects inside a complex set-up of four arrays of speakers. Then, using a refinement of the existing technology of sound wave management, they lifted bubbles, a screw and a tiny piece of wood in the air and moved around in all direction within the experiment’s confines. Here’s the video.
The study researchers said, “Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its center is also utilized. The other is the manipulation principle by which a localized standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays.”
Researcher Yoichi Ochiai from University of Tokyo said, “The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes.”
Here’s another video.