Trapping Large Objects with Sound

Acoustic traps use sound waves to capture and move an object remotely. But, to date, these traps have only worked for objects smaller than half the wavelength of the trap’s sound waves—about 4 mm for the most common trapping wavelengths. Now researchers have gone beyond this size barrier with a new type of acoustic trap. Their approach could be used in applications that require the careful positioning and manipulation of both millimeter- and centimeter-sized objects, such as medical procedures like removing kidney stones.