Brainy Quote of the Day

Wednesday, July 17, 2013

Sound Levitation...

A new approach to contact-free manipulation could be used to combine lab samples while also
preventing contamination

By Josh Howgego and Nature Magazine

Water droplets, coffee granules, fragments of polystyrene and even a toothpick are among the items that have been flying around in a Swiss laboratory lately — all of them kept in the air by sound waves. The device that achieves this acoustic levitation is the first to be capable of handling several objects simultaneously. It is described today in the Proceedings of the National Academy of Sciences.

Typically, levitation techniques make use of electromagnetism; magnetic forces have even been used to levitate frogs. It has long been known that sound waves could counter gravity, too, but so far the method has lacked practical application because it could do little more than keep an object in place.

To also move and manipulate levitating objects, Dimos Poulikakos, a mechanical engineer at the Swiss Federal Institute of Technology (ETH) in Zurich, and his colleagues built sound-making platforms using piezoelectric crystals, which shrink or stretch depending on the voltage applied to them. Each platform is the size of a pinky nail.


Scientific American: Sound Waves Levitate and Move Objects

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