Engineering news
The team, from the University of Bath and the University of Chicago in Illinois, investigated how materials ‘cluster’ together when they are not on a hard, flat surface.
The researchers used sound waves to levitate roughly 1mm-diameter particles of polyethylene. The pieces then interacted with each other in mid-air, in small two-dimensional groups of six or seven.
Five particles or fewer clustered in just one configuration, but the particles formed a number of different shapes when six or more were present. The scientists captured the configurations using high-speed cameras during levitation, finding three distinct shapes – parallelogram, chevron and triangle. Adding one more particle gave four shapes – flower, turtle, tree or boat.
By changing the sound frequency, the team manipulated the clusters and influenced the emergent shape. They found that rearranging the shapes often depended on one particle acting as a ‘hinge’, swinging around the others to reconfigure. This could be “very useful” in a range of potential applications including soft robotics – where scientists and engineers use soft, manipulable materials to create robots with more flexibility and adaptability than those made from rigid materials.
“We've found that, by changing the ultrasound frequency, we can make the particle clusters move about and rearrange,” said Dr Anton Souslov from the University of Bath. “This opens up new possibilities for manipulating objects to form complex structures. Maybe these hinges that we observe could be used to develop new products and tools in the fields of wearable technology or soft robotics.”
Soft robot demonstrators are frequently hailed for their ability to change shape to fit through tight gaps, making them useful for search-and-rescue operations and other applications where safe co-operation with humans is vital. Adding levitation could create even more flexible, useful devices.
The team now wants to combine greater numbers of particles for more complex structures.
The study was published in Nature Physics.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.