UK researchers have developed technology that can bend sound waves around an obstacle to levitate an object above it.
Ultrasonic waves have previously been used to create levitation, but could not bypass obstacles. SoundBender, developed by Professor Sriram Subramanian, Dr Gianluca Memoli and Dr Diego Martinez Plasencia at the University of Sussex, is a new technology capable of producing dynamic self-bending beams that enable both levitation of small objects and tactile feedback around an obstacle.
“This is a significant step forward for ultrasound levitation and overcomes a significant drawback that has been hampering development in this field,” said Memoli, a lecturer in novel interfaces and interactions at the university. “We have achieved incredibly dynamic and responsive control, so that realtime adjustments are just one step away."
To do this, the team developed a hybrid system combining the versatility of phased arrays of transducers (PATs) with the precision of acoustic metamaterials. This helped mitigate against the limitations on sound field resolution and variability that hampered previous approaches.
With SoundBender, the metamaterial provides a low modulator pitch to help create sound fields with high spatial resolution while the PAT adds dynamic amplitude and phase control of the field.
The technology allows users to experience haptic feedback beyond an obstacle; to levitate around an obstacle and to manipulate non-solid objects such as changing the direction of a candle's flame.
The development opens up new potential for ultrasound levitation technology, which is more versatile than techniques such as magnetic or electric levitation as it doesn’t require any special properties in the object to be levitated. It could be applied to materials such as liquid and food.
"Following our breakthrough, the potential now is for a device that can bend around larger objects, potentially even as the obstacle is moving,” said Subramanian, professor of informatics at Sussex and emerging technologies chair at the Royal Academy of Engineering. “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."