Researchers Use Sound Waves To Levitate Small Objects

Thursday, 20 December 2018 - 2:16PM
Weird Science
Physics
Thursday, 20 December 2018 - 2:16PM
Researchers Use Sound Waves To Levitate Small Objects
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In a study published earlier this week in Proceedings of the National Academy of Sciences, a team of researchers from Spain and the UK presented a new technique of acoustic levitation that, for the first time, allows for the independent movement of objects along more than one axis using sound waves. 

According to Motherboard, standing waves are sounds waves that are reflected off of a surface and back onto themselves forming fixed points (nodes) instead of peaks and valleys. In acoustic levitation, those waves are used to trap and push objects back and forth. The new technique, called holographic acoustic tweezers, uses an array of 250 small loudspeakers that creates nodes capable of suspending objects and moving them individually. Algorithms were used to make the objects appear as if they were being moved around by invisible hands in a choreographed dance.



Beyond creating a trippy science lab trick, the researchers say that the new technique could be useful for the medical field, specifically as a tool for surgery. Instead of cutting a patient open with a laser to implant a small device, doctors could (in theory) use sound to control the movement of a biomedical device inside of the body. "Optical tweezers are a fantastic technology, but always dangerously close to killing the cells being moved," Bruce Drinkwater told University of Bristol News. "With acoustics we're applying the same sort of forces but with way less energy associated. There's lots of applications that require cellular manipulation and acoustic systems are perfect for them." In the study, the system worked on objects up to 25mm (0.98 inch) which would limit its uses, but its possible that the technique could be further developed to move slightly larger things. 

To show off the accuracy of the movements allowed by the new technique, the researchers demonstrated the ability to use two tiny spheres attached to thread to sew a piece of fabric. They also showed that up to 25 spheres can be individually moved at once. "Now we have more versatility," Drinkwater said of the new technique. "Multiple pairs of hands to move things and perform complex procedures, it opens up possibilities that just weren't there before."
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