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In the latest case of science fiction turning to science fact, researchers from the Universities of Bristol and Sussex in the UK have invented the world’s first sonic tractor
A perennial favourite in old-school sci-fi like Star Trek, the tractor beam in science fiction is essentially an invisible ray that’s used to grab and tow items in outer space.
As with so many ideas first seen in sci-fi, the idea of a tractor beam quickly fascinated real scientists and now a British team reckons they’ve come up with the answer in the form of sound waves.
" It 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's brilliant," Asier Marzo, PhD student and the lead author, enthused in a statement.
The research team has created three-dimensional acoustic fields with shapes such as fingers,... [+]
The researchers, whose study was published in Nature Communications, have built a working tractor beam that uses high-amplitude sound waves to generate “an acoustic hologram”, which can grab and move objects.
The days when the International Space Station will be able to tow in asteroids for study are still pretty far off though. This tractor beam takes the holographic shape of fingers or a cage in order to manipulate small objects, rather than huge spacecraft or space rocks.
While it won’t be much use in space, the team does believe that the technique could be quite useful here on Earth. They suggested that the holograms could be employed on a production line to handle and assemble delicate objects that shouldn’t be touched or a miniaturised version could be used to move drugs or microsurgical instruments through the human body.
The scientists developed the technique in collaboration with Ultrahaptics, a firm set up in 2013 based on technology originally developed at the University of Bristol. The company’s tech allows users to get tactile feedback without wearing or touching anything, through ultrasound projections.
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To take this idea further and turn it into a tractor beam that can move physical objects, the team used an array of 64 miniature loudspeakers to project high-pitch, high-intensity sound waves to create a force field that can “hold” an object. Then, careful control of the output from the speakers allows them to move or rotate the object as well.
"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," explained Sriram Subramanian, professor of informatics at the University of Sussex and co-founder of Ultrahaptics.
So far, the tractor beam works in three holographic configurations – a pair of fingers or tweezers, a twister that traps the object at its core and a cage that surrounds the object and holds it in place. The next step for the team is to try to build different variations of the systems for different applications. The scientists are working on a bigger version that will try to levitate a football from ten metres away and a smaller version aimed at manipulating particles in the human body.
