Out of the realm of 'Star Wars': Scientists develop sonic tractor beam
Researchers create a sonic tractor beam, capable of lifting small objects.
The research team has created three-dimensional acoustic fields with shapes such as fingers, twisters and cages. These acoustic fields are the first acoustic holograms that can exert forces on particles to levitate and manipulate them.
Courtesy of Asier Marzo, Bruce Drinkwater and Sriram Subramanian
Tractor beams may seem like the stuff of science fiction, but in recent years, they have moved out of the realm of "Star Trek" and "Star Wars." Last year, physicists created a long-distance optical tractor beam that can repel and attract objects. Now, an international team of scientists has developed a sonic tractor beam that can actually lift small objects.
Using high-amplitude sound waves, the researchers generated an acoustic hologram that can pick up small objects, as described聽in聽聽in the journal聽Nature Communications.听
"I think it is important to explore all the different technologies for contactless manipulation," study lead author and PhD student Asier Marzo . "In the past, our hands were our main tool to manipulate objects but we need new tools for solving today鈥檚 challenges."
"Using sound waves has several advantages: sound waves have the best ratio of input power to exerted force. Sound can travel through air, water and human tissue." he said.
Study co-author Bruce Drinkwater, a mechanical engineer, , 鈥漌e've all experienced the force of sound 鈥� if you go to a rock concert, not only do you hear it, but you can sometimes feel your innards being moved.鈥� He said, "It's a question of harnessing that force."
The frequency of the sound waves determines what the mysterious ray can pick up.听
"The lower the frequency, the larger the object," Mr. Marzo explained. "So for instance if you want to levitate a soccer ball, the necessary sound waves will be dangerous for human hearing."
He also , 鈥淭o pick up a beach ball-sized object would require 1,000 Hz. But that enters the audible range, which could be annoying or even dangerous to the human ear.鈥�
Fictitious tractor beams can carry people and even spaceships. But this sonic tractor beam likely doesn鈥檛 have the same abilities.
鈥淭he power required to lift a human would probably be lethal,鈥� said Marzo. 鈥淚f you apply too much ultrasound power to a liquid, you will create microbubbles.鈥� As most of a human body is water, this method likely won鈥檛 be safe.
Still, this creation could be groundbreaking.听
鈥淗ere we have managed to control the sound to a degree never previously achieved,鈥� Dr. Drinkwater said in .听
Marzo said: "It was an incredible experience the first time we saw the object held in place by the tractor beam. All my hard work has paid off, it's brilliant."