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Scientists create acoustic 'tractor beam'

A team of engineers from the Universities of Sussex and Bristol built a sonic tractor beam that uses sound waves to remotely manipulate objects.

By Mike Tokars, Staff

A team of engineers from the Universities of Sussex聽and Bristol built a device that uses sound waves to remotely lift and move objects 鈥 just like a UFO-abduction tractor beam, but without the aliens and malice.

鈥淚n our device we manipulate objects in mid-air and seemingly defy gravity,鈥澛爏aid Sriram Subramanian, professor of informatics at University of Sussex 鈥 formerly of Bristol 鈥 in a press release.聽

But there is nothing supernatural about the sonic tractor beam.

In a paper published Tuesday in the聽Nature Communications, Dr.聽Subramanian and his colleagues explain that it works using聽by surrounding an object with high-pitched, high-intensity sound produced by 鈥64 miniature loudspeakers (driven at 40Khz with 15Vpp, around 9 Watts of power)鈥 that create an acoustic hologram, or force field, in which the object can be immobilized, levitated, moved and rotated by carefully controlling audio output.

In testing, scientists controlled a spherical bead made of expanded polystyrene and聽measuring 1.98mm in diameter. Researcher Asier Marzo said, 鈥淚t was an incredible experience the first time we saw the object held in place by the tractor beam. All my hard work has paid off, it鈥檚 brilliant.鈥

Professor Bruce Drinkwater, of Bristol University鈥檚 Department of Mechanical Engineering, said, 鈥淲e all know that sound waves can have a physical effect. But here we have managed to control the sound to a degree never previously achieved.鈥

The team discovered three shapes of acoustic force fields capable of working as a tractor beam. The first, 鈥渞esembles a pair of fingers or tweezers;鈥 the second is an 鈥渁coustic vortex鈥 that traps an object at its core; and the third is 鈥渂est described as a high-intensity cage,鈥 that holds an object in place from all directions.

The team is working on variants of the technology, including a larger beam, 鈥渨ith a different working principle,鈥 that will hopefully levitate a soccer ball from 30 feet away; and a scaled down version, for 鈥渕anipulating particles inside the human body,鈥 which could aid in microsurgery. The engineers also believe their sonic tractor beam carries the capacity for a wide array of applications, such as a 鈥渟onic production line,鈥 that could assemble delicate products without physical contact.

The sonic tractor beam was created in a partnership with Ultrahaptics, a company co-founded by Professor Subramanian聽in 2013 with technology originally developed at Bristol, which employs ultrasound for projection of sensations, 鈥渢hrough the air and onto the user鈥 鈥 enabling one to 鈥渞eceive tactile feedback without needing to wear or touch anything.鈥

With Ultrahaptics, users are able to 鈥溾檉eel鈥 touch-less buttons and get feedback for mid-air gestures or interact with virtual objects.鈥 The company is currently courting commercial customers from multiple markets.