Japanese scientists have been successful in moving an object in a three-dimensional space through a complex system of acoustic levitation, surpassing previous research endeavors that lifted the objects in two dimensions.
In order to move expanded polystyrene particles of 0.6 mm and 2 mm in diameter, the Japanese scientists at the University of Tokyo and the Nagoya Institute of Technology had to place the objects inside a complex set-up of four arrays of speakers. Using a refinement of the existing technology of sound wave management, bubbles, a screw and a tiny piece of wood were airlifted and moved around in all direction within the experiment’s confines.
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 and, so far, this method has been used to levitate lightweight particles, small creatures, and water droplets.
The acoustic axis of the ultrasound beam in these previous studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, researchers considered extended acoustic manipulation whereby millimeter-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays.
Source from: http://rt.com/news/3d-japan-objects-levitation-102/