Video: DIY portable acoustic tractor beam costs £70

Previous tractor beams using soundwaves are more complex and costly

A team of researchers from the University of Bristol have shown it’s possible to create a simplified tractor beam using readily available parts with a total cost of less than £70.

Recently, soundwaves were used to create a working tractor beam that can move heavier objects made of different materials and that operates both in air or water without damaging the trapped objects. 

However, to generate an acoustic tractor beam a phased array of more than 50 channels is required and each channel needs to be composed of a signal generator and an amplifier.

This complexity has delayed the spread of acoustic tractor beams that can be used for contactless handling in biophysics or medical applications. 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. 

In the paper, published in Applied Physics Letters, researchers from the Department of Mechanical Engineering at the University of Bristol, have shown that it is possible to build a simplified tractor beam using only one electrical signal and a passive wave modulator.

The passive wave modulator is a type of acoustic lens that can alter the transmitted or reflected waves. The research team’s passive wave modulator can be made in various different ways. In one example it’s a collection of tubes with different lengths and in another it’s a carefully contoured surface. In both cases it can be 3D printed using an off–the-shelf printer. 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.

Asier Marzo, research assistant and the lead author, said that the technique will reduce the cost and complexity of tractor beams, making a more affordable technology for manipulating and analysing levitated samples. 

The university has released a YouTube video with instructions that show how people can build their own acoustic tractor beam, step-by-step, with components costing less than £70.