Austrian scientists working to perfect acoustic levitation have broken through a critical barrier by using electrical charges, allowing them to lift several objects simultaneously while maintaining their separation.
The researchers behind the breakthrough suggest that their new approach will offer researchers in micro robotics, materials science, and other emerging fields that rely on creating dynamic structures from small building blocks an unprecedented capability of simultaneously manipulating several objects in mid-air without them clumping together.
Scott Waitukaitis, now an assistant professor at the Institute of Science and Technology Austria (ISTA), began evaluating acoustic levitation in 2013 when the technology was still in its nascent phases.
“While acoustic levitation was being used in acoustic holograms and volumetric displays, it was essentially geared toward applications,” the professor explained in a statement detailing the ISTA team’s work. “I had the impression that the technique could be used for much more fundamental purposes.”
A central limitation to expanding acoustic levitation beyond these applications is a phenomenon the team called “acoustic collapse.” Although individual particles can be levitated and manipulated in mid-air with sound, the ISTA team said that when researchers tried to levitate multiple particles simultaneously, they tend to “snap together like magnets in mid-air.”
“This ‘acoustic collapse’ occurs because the sound scattering off the particles creates attractive forces between them,” they explain.
When hunting for solutions, Sue Shi, a PhD student in the Waitukaitis group and the first author of the study, said they initially tried to separate levitated particles individually so they would form into repetitive patterns.
“Originally, we were trying to find a way to separate levitated particles so that they would form crystals,” Shi explained.
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