Levitation is often thought of as the realm of magicians or The Jetsons, but it is technically possible. That said, the tech seems to be moving pretty slowly. Now, researchers at the University of Sussex have developed SoundBender, a technology that bends sound waves around obstacles to acoustically levitate objects above them.

The SoundBender is a hybrid system, combining phased arrays of transducers (PATs) and acoustic metamaterials. PATs are made up of a series of small transducers that each give off pulses of ultrasound waves, which can be directed by changing the order they pulse in. These are arranged in a rectangular plate, above which sits a circular metamaterial designed to guide the sound waves up and around, creating a "hollow" space in the middle.

This combination allows small objects to hover above obstacles placed in the center of the sound field, which the team demonstrated by levitating a particle over the top of a Lego figure. The process could also be used to generate haptic feedback when someone places their hand in the beam, or to move non-solid objects – controlling a candle's flame, for example, or moving clouds of particles to create visible "holograms."

"This is a significant step forward for ultrasound levitation and overcomes a significant drawback that has been hampering development in this field," says Gianluca Memoli, co-creator of SoundBender. "We have achieved incredibly dynamic and responsive control, so real-time adjustments are just one step away."

As for what you might one day be able to do with this technology, the team has a few ideas. SoundBender could be put to work in interactive museum displays, directing smells from diffusers to targeted spots or rooms, or sculpting shapes out of fire or fog. That last bit sounds like it begins to cross over with the team's previous work in fog screens like MisTable and MistForm.

"Following our breakthrough, the potential now is for a device that can bend around larger objects, potentially even as the obstacle is moving," says Sriram Subramanian, co-creator of SoundBender. "We are also pursuing how to make the device broadband so it can work for all frequencies of sound. This would allow, for instance, sending the music of a radio behind a corner or creating zones of silence in the middle of a dance floor."

The research was presented at the ACM User Interface Software and Technology Symposium in Berlin this week.

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