A small polystyrene ball held in the air entirely by sound

Tractor beam moves objects using sound waves

A science-fiction like technology that can move objects using sound waves has been developed by British researchers. 

Described as the world’s first sonic tractor beam, the system developed by a team from the University of Sussex, University of Bristol and Ultrahaptics, can so far only handle very small and lightweight items but the scientists believe it can already find applications in many fields.

"In our device we manipulate objects in mid-air and seemingly defy gravity,” said Sriram Subramanian, professor of informatics at the University of Sussex. “We can individually control dozens of loudspeakers to tell us an optimal solution to generate an acoustic hologram that can manipulate multiple objects in real-time without contact.”

The tractor beam, described in the latest issue of the journal Nature Communications, uses high-amplitude sound waves to trap the objects and keep them airborne above a platform consisting of 64 miniature loudspeakers.

The tractor beam surrounds the object with high-intensity sound that creates a force field capable of keeping the objects in the air. By manipulating the output of the loudspeakers, the object can be held in place, moved or rotated.

In a video published on YouTube, a small polystyrene ball is seen levitating above the sound beam-generating platform.

"We all know that soundwaves can have a physical effect,” said Bruce Drinkwater, Professor of Ultrasonics in the University of Bristol's Department of Mechanical Engineering, who cooperated on the research. “But here we have managed to control the sound to a degree never previously achieved."

In future tractor beams could form a basis for sonic production lines, transporting and manipulating tiny objects and assembling them without physical contact.

The researchers envision the technology could be used for targeted drug delivery inside the body or to transport microsurgical instruments through living tissue.

“Acoustic waves can penetrate through flesh, vessels and bones,” explained Asier Marzo, PhD student at the University of Sussex and lead author of the study. “With this technology you may be able to trap a particle [of a medicine] and move it around so that it can affect only a certain part of the body.”

The team is already working on a smaller more precise version of the system that would be able to manipulate particles inside the body. They also want to develop a more powerful system capable of levitating a soccer ball from 10 metres away

In the video below, a tiny polystyrene ball is seen held in the air by the sound-based system:


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