Tractor beam – science fact not fiction

The concept of a tractor beam is familiar from science fiction classics such as Star Wars and Star Trek. Now a team of physicists at the University of Dundee have turned science fiction into science fact by creating a functioning acoustic tractor beam

 
The Dundee researchers – working in collaboration with colleagues at Southampton University and Illinois Wesleyan University - used energy from an ultrasound array to exert force behind an object and pull it towards the energy source.
“This is the first time anyone has demonstrated a working acoustic tractor beam and the first time such a beam has been used to move anything bigger than microscopic targets,” said Dr Christine Demore, of the Institute for Medical Science and Technology (IMSAT) at Dundee.
“We were able to show that you could exert sufficient force on an object around one centimetre in size to hold or move it, by directing twin beams of energy from the ultrasound array towards the back of the object.”
The team used an ultrasound device that is already clinically approved for use in MRI-guided focused ultrasound surgery.
The results of their research have been published in the journal Physical Review Letters.
The Dundee researchers, together with Dr Gabe Spalding at Illinois Wesleyan University, have previously demonstrated that another piece of sci-fi technology – Dr Who’s sonic screwdriver – could be created using a similar ultrasound array, in that instance using the acoustic beam to both push away an object in its path and causing it to rotate.
While their work has caught the interest of sci-fi buffs, it does have significant potential to further develop ultrasound-based clinical techniques.
“Our research could lead to big advances in the application of ultrasound-based techniques in sectors such as healthcare,” said Dr Demore.
The team’s work was carried out as part of the £3.6million ‘Electronic Sonotweezers: Particle Manipulation with Ultrasonic Arrays’ programme initiated by the Engineering and Physical Sciences Research Council (EPSRC).
The programme combines expertise at four UK universities - Bristol, Dundee, Glasgow and Southampton - as well as a range of industrial partners. Their extremely close and highly productive collaboration, supported by the four-year EPSRC grant, has established the UK as a world leader in this fast-growing technology.
Professor Sandy Cochran, of the University of Dundee said, “Our partnership with industry has been vital to developing devices and capabilities that are delivering unprecedented sophistication in the field of ultrasound.”

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