Tiny ‘Tractor Beam’ Moves Objects With Acoustic Holograms

By Janine Anderson | October 27, 2015 11:00 am
Scientists created acoustic holograms with shapes such as tweezers, twisters and cages that exert forces on particles to levitate and manipulate them.

Scientists created acoustic holograms with shapes such as tweezers, twisters and cages that exert forces on particles to levitate and manipulate them. (Credit: Asier Marzo, Bruce Drinkwater and Sriram Subramanian)

It’s a classic science fiction scene: A large vessel moves near a smaller one, captures it in a so-called tractor beam, and pulls it inside.

Now imagine bringing that technology to life, but instead of moving meddlesome space ships, terrestrial tractor beams would perform touchless assembly, microsurgery or deliver drugs directly to the body part that needs them. You may not have to imagine for long: A British research team is making early strides toward developing small-scale tractor beams, using high-amplitude sound waves to create invisible force fields they can adjust in real-time.

Patience, Patience, Patience

It took months to get right.

“When the experiments were not working (for about six months) they were some of the most dispiriting you could think of,” stated Bruce Drinkwater, a professor of ultrasonics at the University of Bristol. “Imagine repeatedly dropping small polystyrene spheres and watching them fall, or fire off in the
wrong direction. So, when Asier (Marzo) showed us it working, we were speechless.”


He shook the hands of everyone present, then said “This will get us into Nature.

And, it did.

Their research, published today in the journal Nature Communications, was a collaboration between the universities of Bristol and Sussex, and Ultrahaptics, a company developing technology that uses acoustic waves to create a virtual sense of touch.

The team set up an array of 64 miniature loudspeakers, each sending out sound beyond the range of human hearing, to create an acoustic hologram that could surround objects and hold them in place. By changing the speakers’ output, they could set up various acoustical force fields that functioned like fingers, twisters or cages, and then use them to manipulate the objects.


Big Things, Small Package

The method won’t work in the vacuum of space where sound can’t travel, but they have plenty of ideas on where to go next. Drinkwater stated they are working to miniaturize the system, making it capable of working with incredibly small particles.

“We have in mind cells and drug-holding micro-capsules,” Drinkwater stated in an email. “If we could manipulate these within the body, e.g. to deliver drugs to tumors, this would be hugely important.”

The waves could theoretically be used to manipulate blood clots, kidney stones, microsurgical instruments or to move cells inside the body without any incisions, wrote Marzo, a PhD student at the Public University of Navarre. He also sees viability for the technology in space, controlling floating objects
in zero-gravity environments in which astronauts work.

“The possibility of holding and manipulating objects from a distance and without physical contact is intrinsically exciting,” Marzo stated in an email. “It can be something mundane like levitating the remote control from the table to your hand, or something incredibly sophisticated like tangible displays composed of millions of levitating particles acting as pixels.

And why not? I like the ultimate vision of rearranging asteroids or building things atom by atom.”

CATEGORIZED UNDER: Technology, top posts
  • Maedhros1978

    Now I want my sonic screwdriver!

  • Matthew Skay

    This is neat!! :)

  • Austin Buchla

    Wow, go John Rosser! :^)

  • Kirk

    Now all they have to do is reverse the effect to have a propulsion unit.

  • Van Snyder

    It’s “interesting” that Taylor Wang and the experiments he made for containerless processing on the Space Shuttle were not mentioned.

  • Adam T. Wildeman

    build it so it can manipulate photon particles to create hard light VR holographs there’s your hallodeck. LOL

  • Andy

    “For He spoke, and it came to be; He commanded, and it stood firm.” (Psalm 33:9)

  • Rodney Bartlett


    Astronomers say, radial velocity measures a star’s movement as an orbiting planet pulls on it. Combining Newtonian interpretations of gravity with relativistic ones allows construction of Star Trek’s Tractor Beam, which lets starships tow other objects around in space.

    We start with Einstein’s idea that gravitation – and the gravitational waves which compose it – is a pushing force, where objects aren’t pulled towards e.g. the centre of Earth but are pushed in that direction by the curvature of space-time. The star can be thought of as the primary focus of gravitational waves from deep space while the orbiting planet is regarded as a secondary focus (think of how lenses and mirrors create different foci inside telescopes). Recalling Einstein’s 1919 paper that asks if gravitation plays an essential role in formation of elementary particles (and believing the paper is not a mistake), the star would have the greatest mass since it’s the primary focus while the planet’s mass is secondary.

    As the planet goes round the star, there would be shifts in the relative positions of the primary and secondary focus. This could be viewed in the classical sense of the planet pulling on the star and causing it to wobble. Not only does Newton’s maths describe this situation well, but the situation could be the origin of Newton’s describing gravity as a pull (the planet seems to pull on the star and make it wobble).

    Translating all this to starships and whatever they’re towing thru space-time, relative shifts in the primary and secondary foci (even tertiary and more foci) permit exquisite control over the placement of the cargo being towed. Control of placement is possible in time as well as space if time is regarded as merely the motions of particles in space, thus unifying space and time in the inseparable union of space-time. Control of placement in time as well as space can only be further regarded as a possibility if 1) we accept that gravitation plays an essential role in formation of elementary particles, and 2) if we accept the Wheeler-Feynman absorber theory’s proposal that gravitational waves travelling back and forth in time is not just a mathematical device.


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