Scientists create a Star Trek like tractor beam

Since Star Trek, tractor beams have been the staple of space based science fiction. However, a group of researchers belonging to the Universities of Sussex and Bristol, in collaboration with ultrasound technology startup Ultrahaptics, have actually created a sonic tractor beam using a single emitter made up of tiny speakers.

Acoustic levitation, the ability of sound waves to levitate objects, has been known to science for some time, However, this is the first time that high amplitude ultrasonic sound waves, which aren't even audible to the human ear, have been used to levitate a small polystyrene bead. Also, acoustic levitation requires extremely bulky equipment including multiple speaker banks and/or sound reflectors. On the other hand, the current sonic levitation technique demonstrated by researchers only utilized a single emitter made up of 64 miniature loudspeakers.

“We all know that sound waves can have a physical effect,” said Bruce Drinkwater, professor of ultrasonics at the University of Bristol. “But here we have managed to control the sound to a degree never previously achieved.”

Ultrasonic levitation. Video credit: Nature Video

The researchers led by Asier Marzo, have published their technique in the journal Nature Communications on 27 October, 2015. They have developed an algorithm which utilizes three different types of force fields as tractor beams. The first mimics a pair of fingers or tweezers which can hold and rotate the object. The second is an acoustic vortex which traps the object within its core and the last is a high intensity cage-like force field which surrounds the object from all sides and holds it in place.​​

Sriram Subramanian, Professor of Informatics at the University of Sussex and co-founder of Ultrahaptics, explained: "In our device we manipulate objects in mid-air and seemingly defy gravity. We can individually control dozens of loudspeakers to tell us an optimal solution to generate an acoustic hologram that can manipulate multiple objects in real-time without contact.”

The researchers believe that their technique could be adapted for use in numerous applications in various fields. For example, this technique could be used to create a a sonic levitation based production line which would assemble delicate parts without any human contact. The technique could also be used to create industrial and home appliances with invisible but tactile control knobs which would be controlled by sound.  

Acoustic Holograms that Levitate Particles. Video credit: BristolIG

​​“My main target for the future is in vivo levitation,” Marzo says. Since ultrasonic waves are gentle with the body, Marzo expects that this technique will play a big role in future surgeries and drug delivery systems.For example, a microscopic version of this technique could be potentially used to remove kidney stones, clots and deliver drugs directly inside human tissue.

Many of the researchers are associated with the ultrasound technology company Ultrahaptics, which is involved in commercializing this technology for various consumer and industrial uses.

​Levitation using sound waves. Video credit: University of Sussex 

The research team now plans to create different variations of their technique. A smaller version, focusing on "in-vivo levitation", designed specifically to work inside the human body and a larger version which aims to levitate a soccer ball placed 10 meters (32.8 feet) away.

References:

• "Holographic acoustic elements for manipulation of levitated objects​" – Asier Marzo et al. – October 27, 2015. Nature Communications   6,   Article number:   8661   doi:10.1038/ncomms9661

Featured image credit: University of Sussex