A class of robots made from thin sheets of PET material can snap into any of hundreds of stable shapes. Credit: Zhou et al 2025, Science Advances
Researchers have constructed a new class of robots from sheets of thin material that can bend into hundreds of different structures to move across surfaces and grasp objects.
The team from North Carolina State University in the US suggest their creation could have broad applications across the fields of medicine, space exploration and soft robotics.
“Our goal was to bridge metamaterials and robotics, and we think the results are promising,” says author of the study and professor of mechanical and aerospace engineering, Jie Yin.
“We start out with simple polymer sheets that have holes into 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.”
The team used the polymer polyethylene terephthalate (PET) to create the metabots. They then cut out a H-shape in each of the polymer sheets and added a ‘piezoelectric’ PVDF film to allow them to remotely control the material.
“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,” says first author Caizhi Zhou, a PhD student at NC State.
The researchers found they were able to create 20 stable states with a single sheet. They then connected as many as 4 sheets together to create an even larger number of stable states.
“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 Zhou.
“For example, if we connect 4 sheets, you have a metabot that can lie as flat as a sheet of paper, but fold into 256 different stable states.”
As the results published in Science Advances show, these metabot networks were not only able to move across a surface, but also transformed into a gripper capable of picking up objects.
The researchers demonstrated their metabot was able to gently handle picking up objects like tofu, glass bottles, conical caps and balls. The gripper could even dig through and pick up sand.
“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.
“We can have a metabot rotate left or right while staying in one place.”
The team is optimistic that the metabot’s simple structure and low energy barriers needed for shape transformation will allow it to smoothly integrate into the world of soft robotics.
However, there are still some limitations.
Many of the metabot’s configurations are only symmetrical. The researchers suspect that further studies into asymmetrical shapes will need to be conducted before their metabots are expanded into the design field.
“This is early-stage, proof of concept work,” says Yin.
“But it demonstrates that this approach to robotics is both inexpensive and highly adaptable.”