Daniel Oberhaus; Motherboard; Thu, 20 Dec 2018
"Acoustic levitation," the ability to move particles using only sound waves, has been explored by researchers for years, but until now it has only been able to move small objects along one axis at a time.
In a study published this week in Proceedings of the National Academy of Sciences, the researchers dubbed their technique "holographic acoustic tweezers" in homage to its likely use cases. They say their device could be used to manipulate tiny biomedical devices inside the human body without invasive surgery or to do advanced manufacturing at incredibly small scales.
Published on Dec 18, 2018
Paper: Holographic Acoustic Tweezers. PNAS. 2018. Asier Marzo, Bruce W. Drinkwater. https://www.pnas.org/content/early/20...
This interference results in the wave having a number of fixed points. Acoustic levitation works when an acoustic system produces a standing wave and objects are trapped in these fixed points, or nodes. Here's what a standing wave looks like, with the nodes marked in red below:
These nodes can then be manipulated to form a desired arrangement of particles, or to perform complex maneuvers using algorithms which subtly change the way the ultrasonic waves are produced by the array.
According to the study, the researchers were able to use their device to manipulate up to 25 millimeter-scale objects in three dimensions.