: Although sound has already been used to levitate objects, researchers have now found a way
to do so at ultrasonic frequencies and with just one bank of speakers, rather than two. To keep a given object floating in the air and also be able to manipulate it, they developed an algorithm that calculates sonic interference patterns, creating a kind of sonic scaffolding, which they call an “acoustic hologram.” The hologram can assume various spatial configurations, such as a pair of tweezers that pinches the object, a tornado-like vortex that entraps the object, and a bottle-like shape in which the object can be contained. Using the acoustic holograms, the researchers were able to move a floating object both vertically and laterally and rotate it. Such a device could have many uses, particularly in medicine, for removing kidney stones, delivering drugs to various parts of the body, and manipulating microsurgical instruments.