Whenever we hear the word tractor beam the first thing that pops into our mind is some kind of sci-fi movie in which a spacecraft uses a light beam to tow an alien or an object inside it. Recently this idea has gathered a lot of attention from researchers and scientists.
The engineers at The University of Bristol have created the world most powerful tractor beam which uses sound waves to stably levitate objects larger than the wavelength of the sound.
Before this invention, it was believed that acoustic tractor beams are not practical as they were only able to contain small objects similar to the size of sound wavelength. Stability was also an issue with larger objects which caused them to orbit rapidly and uncontrollably.
According to the discovery published recently in the journal ‘Physical Review Letters’, the researchers have come up with a new technique. Now instead of using the spinning field of sound waves to keep the object steady, the scientists have developed an instrument which uses rapidly fluctuating acoustic vortices which they describe as ‘mini tornadoes of sound’.
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This technology helps in controlling the rate of rotation and keeps the object steady. Once it is all stabilized, the scientists can then increase the size of the silent core which will allow to levitate and control even bigger objects.
“Acoustic researchers had been frustrated by the size limit for years, so it is satisfying to find a way to overcome it. I think it opens the door to many new applications”, lead author Dr. Asier Marzo said.
The Engineers at Bristol University were able to hold the largest object yet it the acoustic tractor beam, a two-centimeter polystyrene sphere using the ultrasonic waves at a pitch of 40 kHz( a similar pitch that only bats can hear) to make up the acoustic vortices.
This technology is going to open up the doors to many new applications like manipulating individual cells, separating diseased cells from the healthy ones and breaking up things like gallstones, cysts, or tumors. It can also be used to move fragile objects and will help in preserving them.
The Professor of Ultrasonics from the Department of Mechanical Engineering, who supervised the work, said he’s “particularly excited by the idea of contactless production lines where delicate objects are assembled without touching them.”
However, it is still not possible to levitate humans as this experiment involves using lower pitches which make the experiment very loud and dangerous for humans. Though it doesn’t mean that it is not possible to levitate an object larger than a two centimeters sphere. What the study shows is that more acoustic power is required to levitate larger objects stably.
This research is progressing and the only way to go from here is up, who knows soon our sci-fi dreams come true and acoustic hoverboards might become the real thing.