One day, the acoustic tractors will make levitate man...

British researchers managed to levitate a 16 mm diameter polystyrene ball with this technology. A crucial step before making the man avoid him.

The human levitation will perhaps be no longer, tomorrow, science fiction. British researchers have successfully levitated "large" objects through an acoustic tractor beam, reports Phys.org. A first.

Concretely, an acoustic tractive beam makes it possible to move or to levitate particles thanks to the sound, more exactly thanks to the ultrasonic waves. The principle is the same as with a magnetic tractor beam, except that the acoustic version allows to keep in the air most solid objects, but also liquids, food or even small insects.

Master the rotation

The problem is that so far researchers have come up against a technical limit they thought insurmountable. As soon as an object exceeded a certain size-around 2 millimeters-the rotation of the sound field ended up being transmitted to the object, making it turn faster and faster and ejecting it from the levitation field.

A solution has just been invented by engineers from the University of Bristol. In their study published in Physical Review Letters on Monday, January 22, they explain that it is possible to control very precisely the speed of rotation of sound field - and thus its stability - by creating some kinds of "sound tornadoes" which they change periodically the direction of rotation.

Drawing illustration of the different vortices used by Bristol researchers to stabilize their acoustic tractor beam. University of Bristol

"By generating short sequences of acoustic vortices rotating in one direction and then in the other, the tractor beam stabilizes," write the scientists. It becomes possible to levitate objects larger than what was thought possible.

The researchers managed to levitate a 16-millimeter-diameter ball of polystyrene, the largest object ever "worn" by an acoustic tractor beam. "By using a more powerful device, our simulations suggest that we could be able to levitate objects up to 20 millimeters," they write, stating that these tests were done using 40 kHz ultrasonic waves, a frequency that only bats can hear.

Tomorrow, the levitation of being human?

"For years, acoustic researchers have been frustrated by the size limit," said Asier Marzo, an engineer in the Bristol Department of Mechanical Engineering and lead author of the study, in a statement from the University of British Columbia. therefore all the more satisfying. "

"In the future, this method would allow even larger objects to be levitated, whereas it was thought that this was only possible by lowering the frequency, which would have made the experience audible, and especially dangerous, for human beings, "adds Professor Mihai Caleap, who developed the simulations. In theory, it might be possible to levitate a human body with the same technique.

Non-contact assembly line and microsurgery

But the concrete applications of this technique will first serve the industry or medicine. "The standard acoustic levitation methods already have many applications in various fields, such as microscopy, spectroscopy, etc., note the engineers in their study.Our technique will expand the scope."

"Acoustic tractors have huge potential for many applications," says Bruce Drinkwater, professor of ultrasonics at the Department of Mechanical Engineering at the University of Bristol, who oversaw the work, "I'm very excited about the idea of ​​lines. non-contact production, where delicate objects could be assembled without being touched. "

"I think [this discovery] opens doors to many applications, such as the ability to create new medical devices: new drug capsules or microsurgery instruments," says Professor Marzo. It will take a few more years to see the Star Trek or Star Wars tractors in act

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