A group of scientists from the United Kingdom has created a prototype of an “attracting ray,” capable of lifting and moving small objects with the help of sound waves. The very concept of acoustic levitation is not new, but previously scientists could not force objects to levitate with a one-way radiator, so they could not create the beam. The authors published theirresults in Nature Communications .
Acoustic levitation represents a stable position of a weighty object in a standing acoustic wave. Its concept is well known; the expression for the magnitude of the force acting on a solid spherical particle in the field of a standing wave was found back in 1934. However, earlier to obtain the effect, scientists always had to use two-sided sound sources, which made it impossible to create the dream of all fiction lovers – the “attracting ray”.
Marzo and co-authors managed to rework the concept of the device so that only one of the emitters was left. To levitate a polystyrene ball with a diameter of four millimeters, researchers used 64 microdynamics with a total power of nine watts, which created ultrasonic waves of high intensity. By changing the output signal of the speakers, the authors are able to manipulate “suspended on the waves” objects.
The team demonstrated acoustic fields of three different shapes. The force acting on the suspended object in the first case resembles forceps, in the second field it is an acoustic vortex that locks objects in its center, and in the third field represents a “bottle” fixing the position of the body in space.
One of the promising applications of acoustic levitation is the production of amorphized biologically active substances with high bioavailability.
At the moment the team is working on scaling technology: according to their plans, the big version should be able to levitate a soccer ball at a distance of up to ten meters, and a small one – to manage particles inside the human body.