Acoustic Holograms: 3D Sound Shapes Could Help Medical Diagnostics

When most people think holograms, they think of a floating image, a 3D projection of light. But scientists have designed technology that replaces light in the hologram with sound, giving us acoustic holograms that can be used to manipulate small objects. Researchers from the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, have created these acoustic holograms by first printing a hologram plate using a 3D printer, and then transmitting ultrasound waves through it and into another medium, which could be liquid or gas. The uneven surface of the plate causes phase delays in the waves which affect the medium and therefore other objects or particles suspended in or on it. Peer Fischer, who usually works on tiny robots, was "looking for a way to move large numbers of microparticles simultaneously so that we could assemble them into larger more complex structures" when his team came up with acoustic holography, he said in a statement.