Acoustic traction rays use the power of sound to capture particles directly in the air and, unlike the same technology of magnetic levitation, are able to capture most liquids and solids. Engineers at the University of Bristol were the first to prove the possibility of stable control of relatively large objects by an acoustic traction beam, which in theory can be used, for example, to move drugs within the body. Their invention opens the way to man’s levitation.
Earlier it was believed that acoustic traction beams are capable of capturing and moving only small objects, since all previous attempts to catch larger particles than the wavelength failed and led to their uncontrolled rotation. This was due to the transmission by the sound field of rotational movements to objects that began to spin faster and faster until eventually they were thrown away, reports EurekAlert.
The invention of scientists from the University of Bristol, described in the journal Physical Review Letters, uses a different approach – rapid oscillations of acoustic funnels, sound vortices created from loud sounds surrounding the silent core.
Researchers have found that the speed of rotation can be controlled by rapidly changing the direction of the twisting motion of the funnels, thereby stabilizing the traction beam. Thanks to this approach, scientists were able to increase the size of the silent core, which ultimately allowed to retain larger objects.
Using ultrasound at a frequency of 40 kHz (they only hear bats, they are safe for humans), scientists were able to lift two-centimeter polystyrene balls into the air. The size of these objects was equal to two acoustic wavelengths, that is, more than all the objects that could be lifted by a traction beam until now. According to the researchers, in the future this way it will be possible to control the movement of much larger objects.
“Acoustic research for a long time could not overcome the limit of the permissible size of the substance used for levitation. We are very glad that we were able to overcome this barrier. I think this opens the door to many areas, “commented the author of the article, Dr. Asir Marzo of the Faculty of Mechanical Engineering at the University of Bristol.
“In the future, with a higher acoustic power, it will be possible to keep even larger objects in the air. Now it is considered possible only with the use of lower tones, which makes such experiments audible and dangerous for people, “added Dr. Mihail Kaleap, who created the simulation models for the study.
“Sound traction rays have a huge potential in many areas. Personally, I particularly welcome the idea of using a contactless production line where very fragile objects can be collected without touching them, “concluded Bruce Drinkwater, professor of ultra-acoustics, who directed this scientific project.