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Scientists develop acoustic levitation, could enable the eventual levitation of humans

понедельник, 22. июля 2013 - 17:44

For the first time, researchers have succeeded in levitating and moving arbitrarily shaped objects using acoustic (sound) waves. The researchers, from the Swiss Federal Institute of Technology (ETH) in Zurich, have already used their new-found magical powers of levitation to collide a granule of coffee and water to create instant coffee in midair — and more excitingly, a droplet of water and a piece of sodium (the explosively awesome video is embedded below). The same approach could potentially work on humans, though, without further refinements to the technology, we would probably explode or suffer catastrophic internal bleeding.

Acoustic levitation is desirable because, unlike magnetic levitation, it can be used on any object — not just materials and liquids that are magnetic. Likewise, buoyancy can be used to “levitate” some liquids, but again there are strict limitations on what liquids can be used (they must be immiscible, as with water and oil). The only limitation with acoustic levitation is that the object’s diameter must correspond to half the wavelength of the acoustic waves. As you can see, the team have no issues levitating a toothpick — something that would be impossible with both magnetic and buoyancy levitation.

Acoustic levitation has been performed before, but with very limited control of the object’s movement (video below). The breakthrough here is that researchers are able to move their acoustically levitated objects up and down, as well as side to side. The levitation effect is created by standing waves — static (standing) waves that are held in place by a reflector that bounces the same wave back upon itself, causing interference. Whereas waves usually oscillate up and down as they move through the air, a standing wave is essentially static, with the waveform forced to stay in one place. This standing wave creates a consistent upwards pressure that, if it has a strong enough amplitude (volume), can cancel out the gravity of an object placed in the standing wave.

In short, if you have enough power, you could levitate just about anything with acoustic waves — including a human. The power required would be immense, though, and at this point it isn’t clear if a human would even survive the acoustic forces. Furthermore, before you start dreaming of a portable levitation device (a jet pack!), the power requirements would probably be well beyond the capabilities of today’s lithium-ion battery packs. (Levitating a water drop requires around 160 dB).

In reality, this new development — being able to levitate multiple objects and manipulate them in a 3D space — is much more likely to find use on a smaller scale. There are many chemical and biological processes that can be disrupted by contact with a surface, and acoustic levitation is the perfect solution for such situations. Not being confined to magnetism or buoyancy as a means of levitation is also a massive boon for science: Instead of being confined to purely magnetic objects, scientists can now react anything with levitation. This might be as straight forward as reacting water and sodium, as per the video above, or it might be as complex as introducing foreign DNA into other cells using DNA transfection.

Sebastian Anthony

Источник: 
www.extremetech.com
Тэги: 
acoustic levitation