A Tractor Beam Made of Sound
A device uses sound pressure to make virtual tools
Now Bruce Drinkwater, a Professor of Ultrasonics in the Department of Mechanical Engineering at the University of Bristol, and his colleagues, have taken this one step further. Using an array of small speakers, they've produced complex patterns of sound they're calling "acoustic holograms." They then use these to make tools from sound that can hold, and manipulate small objects, allowing them to move them in three dimensions, and rotate them as well.
They think this technology could be useful in "touch-less" manufacturing, and also possibly as a medical device allowing invisible fingers of sound to manipulate things inside the human body.