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Sunday 5 January 2014

Sound wave 3Dvolution: Japanese scientists move objects using acoustic levitation

I love anything to do with FREQUENCY, VIBRATION. My formwe career was as a high school Music Teacher and Private piano and trumpet teacher for many years. So I hope you enjoy this interesting article.


http://rt.com/news/3d-japan-objects-levitation-102/ 



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.

“We considered extended acoustic manipulation whereby millimeter-sized particles were levitated and moved three-dimensionally by localized ultrasonic standing waves, which were generated by ultrasonic phased arrays,” the study stated.

The experiment machine is comprised of audio speakers capable generating inaudible high frequencies sound waves that intersect inside a restrained space. The waves then generate a “moveable ultrasonic focal point,” frequency noise greater than 20kHz, where crossover creates standing waves. Some waves are kept in constant position, serving as a suspending force, while other waves are used to support a floating object jammed in the standing waves.

“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,” the study said.

The practice of moving tiny objects acoustically along the fixed axes is not new, but it was previously applied to 2D, starting from 1975.

“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,” Yoichi Ochiai from University of Tokyo said.

Currently, acoustic levitators are used mostly in industry and for researchers of anti-gravity effects such as at NASA.

Potential energy distribution of ultrasonic standing wave (Image from arxiv.org)Potential energy distribution of ultrasonic standing wave (Image from arxiv.org)
Published on 31 Dec 2013
Three-Dimensional Mid-Air Acoustic Manipulation (2013,2014-)

Yoichi Ochiai / 落合陽一(The University of Tokyo / 東京大学)
Takayuki Hoshi / 星貴之(Nagoya Institute of Technology / 名古屋工業大学)
Jun Rekimoto / 暦本純一 (The University of Tokyo / Sony CSL)

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, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that various materials could be manipulated by our proposed method.

Yoichi Ochiai, Takayuki Hoshi, Jun Rekimoto: Three-dimensional Mid-air Acoustic Manipulation by Ultrasonic Phased Arrays arXiv:1312.4006 [physics.class-ph]
http://arxiv.org/abs/1312.4006