Read More: PHYS.Org
Last year Asier Marzo, then a doctoral student at the Public University of Navarre, helped develop the first single-sided acoustic tractor beam—that is, the first realization of trapping and pulling an object using sound waves from only one direction. Now a research assistant at the University of Bristol, Marzo has lead a team that adapted the technology to be, for all intents and purposes, 3-D printable by anyone (with some assembly required, of course). In addition to a fully detailed how-to video that the group produced for the public, the results of the work developing this do-it-yourself, handheld acoustic tractor beam will appear this week as an open access paper in Applied Physics Letters. Sonic levitation is not new, and the use of sound waves to push around macroscopic objects, or create patterns in resting sand and flowing water, is scattered throughout YouTube and has been for years. This technology, however, is not simply sonic levitation, using sound to push objects around. Based on similar fundamental physics used to create optical traps for decades, these tractor beams are true to their name in that they pull objects, trapping small beads—and even insects—at their foci. "The most important thing is that it can attract the particle towards the source," said Marzo. "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." The first versions of the device that proved the concept possible were not much larger than these new, 3-D printable versions. However, their underlying technology was more complex and required expensive electronics.