Scientists have made levitation a reality using a rather unexpected tool – sound. An Anglo-American research team experimented with sound-based levitation and succeeded in suspending small bits of plastic in mid-air. Their results will contribute to the field of soft robotics, which uses similar plastic materials to create flexible robots.

The researchers also believed that their findings may shed light on the mysterious earliest stage of planet formation. They investigated how materials came together and formed a cluster on a surface that was not hard or flat. They received support from their home institutes, the University of Bath and the University of Chicago.

For their experiment, the researchers acquired tiny pieces of a widely used type of plastic called polyethylene. An individual particle measured just one millimeter in diameter.

They used sound waves to levitate small groups of six to seven particles and control them in mid-air. They observed the 2D interactions between the plastic pieces in each set.

The researchers discovered that groups with five or fewer particles always assembled in a certain way. But once the number increased to six or more, the particles gained the ability to configure their group into more than one shape.

Sound waves not only levitate particles – they also influence the shapes of clustered pieces

The researchers used high-speed cameras to take snapshots of the floating particles. They also evaluated the shapes available to groups of six or seven plastic pieces.