Scientists have found a way to make magic using 3D-printed blocks that create acoustic holograms – a single speaker booms out a tone and objects floating on water move in response to the sound. In one scenario, silicone particles arrange themselves in the shape of a dove then disintegrate when the music stops. In another, bubbles are seen floating above the water’s surface.
The experiment, conducted by physicists at the Max Planck Institute in Stuttgart, Germany, is one of several that proves 3D-printed plates can control sound waves and turn them into a “field” that creates images in water or levitates objects.
Peer Fischer, a co-author on the study, describes it by referring to a popular science-fiction franchise.
It’s just like the holograms you’ve seen on Star Trek. Only we don’t generate an image using light — we do it with sound.
Fischer says this is the first time scientists have been able to create acoustic holograms using just one sound source, the Washington Post reports.
Researchers at the University of Bristol in the UK published a paper last year about their own work on an acoustic system that could levitate items. While the mechanics are similar to Fischer’s, the Bristol team required plenty of transducers – devices that converted electrical signals into sound.
Sound waves approach an object from different directions and at varying frequencies and amplitudes. When the sound waves interact, they create a pressure gradient in air or liquid that can cause objects to move or float.
Fischer says that to generate a complex sound field, there should be a large number of sources, which in turn is costly. So he and his team came up with an alternative solution: they used just one transducer and passed the sound through a plate that distorts it into the kind of sound field they need. The field can’t be seen by the naked eye, but it can be visible by arranging objects on the surface of a liquid. They can also manipulate the sound field to control objects, like making a paper boat move around.
The method, which an expert called “impressively simple,” has many uses, too. It could improve acoustic imaging for medical and industrial purposes. It can also be used in labs to move delicate samples around in petri dishes without touching them or to work on sensitive machinery or electronics parts.
The study was published in the journal Nature.
