Princeton Engineers Develop “Metabot” That Is Both a Material and a Robot

This material can expand, change shape, move, and respond to electromagnetic commands like a remotely controlled robot, even though it has no motor or internal gears.

In a study that echoes scenes from the Transformers movie franchise, engineers at Princeton University have developed a material capable of expanding, changing shape, moving, and responding to electromagnetic commands like a remotely controlled robot even though it lacks any motor or internal gears.

“You can transform between a material and a robot, and it is controllable with an external magnetic field,” said Glaucio Paulino, the Margareta Engman Augustine Professor of Engineering at Princeton.

In a study recently published in Nature, the researchers explain how they took inspiration from origami, the art of paper folding, to design a structure that bridges the gap between robotics and materials science. The result is a metamaterial, a type of engineered material whose unique properties stem from its physical structure rather than its chemical makeup.

The team created it using a blend of basic plastics and specially designed magnetic composites. By applying a magnetic field, they could alter the material’s structure, enabling it to expand, move, and bend in various directions, all without direct contact.

Origami-inspired metabot invention

The team called their creation a “metabot” – a metamaterial that can shift its shape and move.

“The electromagnetic fields carry power and signal at the same time. Each behavior is very simple but when you put them together the behavior can be very complex,” said Minjie Chen, an author of the paper and an associate professor of electrical and computer engineering and Andlinger Center for Energy and the Environment at Princeton. “This research has pushed the boundaries of power electronics by demonstrating that torque can be passed remotely, instantaneously, and precisely over a distance to trigger intricate robotic motions.”

Princeton scientists have created a magnetic, shape-shifting metamaterial, part robot, part origami, that could revolutionize fields from robotics to medicine. Credit: Princeton University

The metabot is a modular conglomeration of many reconfigurable unit cells that are mirror images of each other. This mirroring, called chirality, allows for complex behavior. Tuo Zhao, a postdoctoral researcher in Paulino’s lab said the metabot can make large contortions — twisting, contracting, and shrinking — in response to a simple push.

Xuanhe Zhao, an expert in materials and robotics who was not involved in the research, said the “work opens a new and exciting avenue in origami design and applications.”

“The current work has achieved extremely versatile mechanical metamaterials by controlling the assembly and chiral state of the modules,” said Zhao, the Uncas and Helen Whitaker Professor at MIT. “The versatility and potential functionality of the modular, chiral origami metamaterials are truly impressive.”

Promising uses across fields

Davide Bigoni, a professor of solid and structural mechanics at the Universita’ di Trento in Italy, called the work groundbreaking and said it could “drive a paradigm shift across multiple fields including soft robotics, aerospace engineering, energy absorption, and spontaneous thermoregulation.”

Exploring the technology’s robotics applications, Tuo Zhao, an author of the paper, used a laser lithography machine at the Princeton Materials Institute to create a prototype metabot that was 100 microns in height (a little thicker than a human hair). The researchers said similar robots could one day deliver medicines to specific parts of the body or help surgeons repair damaged bones or tissue.

The researchers also used the metamaterial to create a thermoregulator that works by shifting between a light-absorbing black surface and reflective one. In an experiment, the researchers exposed the metamaterial to bright sunlight and were able to adjust the surface temperature from 27 degrees Celsius (80 degrees Fahrenheit) to 70 C (158 F) and back again.

Another possible use lies in applications for antennae, lenses, and devices that deal with wavelengths of light.

Kresling pattern and magnetic control

Geometry holds the key to the new material. The researchers built plastic tubes with supporting struts arranged so the tubes twist when compressed, and compress when twisted. In origami, these tubes are called Kresling Patterns. The researchers created the building blocks of their design by connecting two mirror-image Kresling tubes at the base to make one long cylinder. As a result, one end of the cylinder folds when twisted in one direction and the other end folds when twisted in the opposite direction.

This simple pattern of repeating tubes makes it possible to move each section of the tube independently using precisely engineering magnetic fields. The magnetic field causes the Kresling tubes to twist, collapse, or pop open, creating complex behaviors.

Paulino said that one consequence of chirality – the mirror-image sections – is that the material can defy the typical rules of actions and reactions in physical objects. “Usually, if I twist a rubber-beam clockwise and then counter-clockwise, it returns to its starting point,” Paulino said. The group created a simple metabot that collapses when twisted clockwise, then reopens when twisted counterclockwise – a normal behavior. However, if twisted in the opposite sequence – counterclockwise then clockwise – the same device collapses, then collapses further.

Paulino said this asymmetrical behavior simulates a phenomenon called hysteresis, in which a system’s response to a stimulus depends on the history of changes within the system. Such systems, which are found in engineering, physics, and economics, are difficult to model mathematically. Paulino said the metamaterial offers a way to directly simulate these systems.

A more distant use for the new material would be to design physical structures that mimic the performance of logic gates made with transistors in a computer.

“This gives us a physical method to simulate complex behavior, such as non-commutative states,” Paulino said.

Reference: “Modular chiral origami metamaterials” by Tuo Zhao, Xiangxin Dang, Konstantinos Manos, Shixi Zang, Jyotirmoy Mandal, Minjie Chen and Glaucio H. Paulino, 23 April 2025, Nature.
DOI: 10.1038/s41586-025-08851-0

Support for the project was provided in part by the National Science Foundation, the Princeton Materials Institute, the Princeton Council on Science and Technology, and the Andlinger Center for Energy and the Environment.

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