Now you can 3D-print your own sonic tractor beam
Tractor beams sound like science fiction straight out of “Star Trek,” but one U.K.-based researcher is showing off how you could make your own using a 3D printer. Short for “attractor” beams, the popular concept refers to a system enabling one distant object to be pulled towards another.
Last year, Asier Marzo, then a doctoral student at the Public University of Navarre, developed the first single-sided acoustic tractor beam that could trap and pull in an object — things like small beads or even insects — by way of sound waves emitting a single direction. Now at the University of Bristol, Marzo has found a way to make this technology more accessible to the average person, according to a press release from the American Institute of Physics.
Marzo has created something of a how-to guide to making tractor beams, with a soon-to-be-published open access paper in Applied Physics Letters as well as a video posted to YouTube that explains his process.
“The most important thing is that it can attract the particle towards the source,” Marzo said in the release. “It’s very easy to push particles from the source, but what’s hard is to pull them toward the source; to attract the particles. When you move the tractor beam, the particle moves, but otherwise the trap is static. It can levitate small plastics — it can also levitate a fly and small biological samples. It’s quite handy.”
In the past, expensive equipment was required to create these tractor beams.
“Previously we developed a tractor beam, but it was very complicated and pricey because it required a phase array, which is a complex electronic system,” Marzo added. “In this paper, we made a simple, static tractor beam that only requires a static piece of matter.”
Basically, the sound waves are shaped by the internal design of the 3D-printed machine, modulated by what Marzo called “metamaterial,” or a “piece of matter with lots of tubes of different lengths.”
As the sound waves travel through all these tubes, they are essentially molded into the correct “phases” that waves need to be in to generate the tractor beam.
Marzo acknowledged that, initially, it wasn’t easy to find a way to create such a complex structure from an at-home 3D printer.
“We needed to engineer the tubes very well to allow them to be 3D-printed with a normal 3D printer,” he said. “A normal 3D printer has a lot of limitations.”
For home-based hobbyists who want to create their own space-age tractor beam, they can buy the necessary components easily from Amazon for less than about $70, Marzo said.
Of course, this technology’s potential is more scientifically significant than just a fun hobby. For example, tractor beams could be used by biologists who are looking to see how certain biological samples act in low-gravity situations. Marzo’s technology is essentially a jumping off point for other researchers to use in their own work.
“Recently there have been several papers about what happens if we levitate an embryo, how does it develop? Or what happens if we levitate bacteria?” he said. “For instance, they discovered salmonella is three times more [virulent] when it’s levitated. Certain microorganisms react differently to microgravity.”
Right now, there are three designs for the device that can work with different object sizes and sound wavelengths. Marzo did stress that even researchers with a full lab at their disposal have difficulty trapping heavier objects and liquids by the tractor beams. He said that trapping objects that are larger than half the wavelength of sound remains a big challenge, and be extremely difficult for the tractor beam rookie at home. Due to these limitations, the most feasible size of an object that could be caught in a tractor beam’s path at home would be just a few millimeters.
