You can now, with some assembly, 3D print your very own tiny sonic tractor beam.
Thanks to the efforts of a research team at Bristol University, technology for a single-sided acoustic tractor beam has now been adapted to be printed and assembled by anyone with the inclination. The publically available specifications are based on the first single-sided acoustic tractor beam, developed last year.
The original technology was developed by Asier Marzo, then a doctoral student at the Public University of Navarre. The tractor beam, rather than using the long-possible sonic levitation to push objects around, functioned true to its name and was able to trap and pull objects using sound waves from only one direction.
Marzo, now a research assistant at the University of Bristol, led his team in changing the technology into something that anyone could produce. Their efforts, beyond adaptation, have resulted in the production of a fully detailed how-to video for the public and an open access paper in Applied Physics Letters that will lay out the results of their development work.
“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 said. “In this paper, we made a simple, static tractor beam that only requires a static piece of matter.”
The principle change from the original technology to the new, more accessible version was the transition from an underlying complex structure that made use of expensive electronics to an architecture that produces the same results structurally rather than electronically. As the sound passes through these elements, the waves are shaped by the internal structure of the 3D printed material.
The sound wave is modulated using a metamaterial which consists of lots of tubes of varying lengths. After passing through said tubes, the sound has the correct phases to create the tractor beam. However, the team face difficulty in optimising this material design to allow common 3D printers to produce the same results as more precise instruments.
Beyond the simple appeal of owning your own tractor beam, the technology may have serious potential for studying low-gravity effects on biological samples. Microgravity research is already an emerging field of interest and the tractor beam may serve as an effective tool for furthering these studies.
“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?” Marzo said. “For instance, they discovered salmonella is three times more [virulent] when it’s levitated. Certain microorganisms react differently to microgravity.”
There are currently three designs of the tractor beam, each with a trapping profile suited to different object sizes as related to the wavelength of sound used. However, the team’s technology is still limited to objects around half the size of the wavelength. For practical frequencies, just above what humans can hear, this limits the current size of trappable objects to a few millimetres.