Researchers from the Department of Mechanical Engineering at University of Bristol, UK, offer step-by-step instructions for building your own acoustic tractor beam. All you need is an off-the-shelf printer and components that can be purchased on the Internet for less than £70 ($86).

The portable tractor beam uses one electrical signal and a passive wave modulator, which is a type of acoustic lens that can alter transmitted or reflected waves.

Researcher Asier Marzo with the portable acoustic tractor beamThe research team’s passive wave modulator can be fabricated in different ways. In one example it’s a collection of tubes with different lengths. In another it’s a contoured surface. Using a single waveform, a static tractor beam can be created. If two waveforms are used, then up and down manipulation of objects can be achieved.

Previous work on tractor beams using sounds waves has opened up applications for contactless handling. For instance, samples of blood could be levitated for visual inspection without any obstruction; chemical compounds could be merged without being contaminated and kidney stones could be removed from the body without the need for incisions.

However, to generate an acoustic tractor beam a phased array of more than 50 channels was required and each channel needs to be composed of a signal generator and an amplifier. These complex electronics have delayed the spread of acoustic tractor beams into the biophysics or medical applications. The University of Bristol technique reportedly will help reduce the cost and complexity of tractor beams and render them a more affordable technology for manipulating and analyzing levitated samples.