Metamorphosis: The Incredible Transformation of Metabots

Researchers have created a class of robots made from thin sheets of material that can snap into hundreds of stable shapes, allowing them to execute a wide variety of actions despite the fact that they have no motor and are made of a single, flat material. These “metabots” essentially resemble animated sheets of plastic, capable of moving around a surface or grasping objects.

“We start out with simple polymer sheets that have holes in them, but by applying thin films to the surface of the polymer we’re able to incorporate materials that respond to electricity or magnetic fields,” says Jie Yin, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University. “These films serve as actuators, allowing us to change the shape of the sheet remotely.”

“By connecting multiple sheets, we create structures that lie flat initially, but can then bend and fold themselves into a wide variety of stable configurations,” says Caizhi Zhou, first author of the paper and a Ph.D. student at NC State. “For example, if we connect four sheets, you have a metabot that can lie as flat as a sheet of paper, but fold into 256 different stable states.”

The research appears in Science Advances.

These flat robots have multiple modes of movement, capable of jumping or crawling at multiple speeds.

“The robots can change their shape and gait to adapt to different terrains or to perform a variety of functions, such as gripping and lifting objects,” says Zhou. “And when we incorporate piezoelectric materials into the thin films, we can cause controlled vibrations in the metabots by varying the voltage and hertz, giving us additional control over their movement. For example, we can have a metabot rotate left or right while staying in one place.”

“This is early-stage, proof-of-concept work, but it demonstrates that this approach to robotics is both inexpensive and highly adaptable,” says Yin. “Our goal was to bridge metamaterials and robotics, and we think the results are promising.”

The paper was co-authored by Haitao Qing, Haoze Sun and Fangjie Qi, who are Ph.D. students at NC State; and by Yaoye Hong, a former Ph.D. student at NC State.