Researchers from the Universities of Bristol and Sussex, in collaboration with Ultrahaptics, have built the world’s first sonic tractor beam that can lift and move objects using sound waves.

Details of the device, published in Nature Communications, describe how the tractor beam uses high-amplitude sound waves to generate an acoustic hologram that is capable of picking up and moving small objects. The technique comes straight from the pages of a science-fiction novel.

“It was an incredible experience the first time we saw the object held in place by the tractor beam,” said Asier Marzo, PhD student and the lead author of the study.

The tractor beam works by using 64 miniature loudspeakers to create high-pitch and high-intensity sound waves. The resulting waves surround the object with sound and this creates a force field that keeps the object in place. By carefully controlling the output of the loudspeakers the object can be either be held in place, moved or rotated.

Sriram Subramanian, professor of Informatics at the University of Sussex and co-founder of Ultrahaptics, which is also working on using ultrasound to bring touch to virtual reality, explained: “In our device we manipulate objects in mid-air and seemingly defy gravity. Here we 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 researchers hope the tractor beam can be developed to serve a wide range of applications. They describe how the current device could be used to transport delicate objects and assemble them, without the need for physical contact, or a miniature version could grip and transport drug capsules or microsurgical instruments through living tissue.

Depending on the desired application the research team have developed three different shapes of tractor beams. The first is an acoustic force field that resembles a pair of fingers or tweezers. The second is an acoustic vortex, the objects becoming stuck-in and then trapped at the core and the third is best described as a high-intensity cage that surrounds the objects and holds them in place from all directions.

Although the concept of an acoustic force field has long been envisioned by scientists, engineers and science-fiction writers, this breakthrough represents the first realised version of a sonic tractor beam that can lift and move objects using sound waves.

Previous work on acoustic studies had to surround the object with loudspeakers, which limits the extent of movement and restricts many applications.

Last year, the University of Dundee presented the concept of a tractor beam but no objects were held in the ray.