Development of soft robotics could hinge on clusters of levitating particles

The research team, from Bath University and the University of Chicago, used sound waves to levitate polyethylene particles of around 1mm in diameter to see how they interact with each other in 2D in groups of six or seven.

When there are five particles, or fewer, the particles cluster in only one configuration.  When there are at least six particles, there are several different shapes they could assemble into.

By levitating the particles and using high-speed cameras the researchers were able to capture these various configurations. They found that groups of six particles can form parallelogram, chevron, and triangle shapes. Adding one more particle meant that particles clustered together in one of four shapes, each resembling a flower, a turtle, a tree, or a boat.

By changing the sound-wave frequency, the team realised it could manipulate the clusters and influence the emergent shape. They found that rearranging the shapes often depends on one particle acting as a “hinge” and swinging around the others to reconfigure, which could be useful in a range of potential applications.