Researchers at Cornell University have developed a tiny robot less than a millimeter in size. The robot is printed from two-dimensional hexagonal “metasheets,” but when electricity is applied, it can transform into a pre-programmed three-dimensional shape and crawl.
The robot’s versatility is due to a new design based on Origi’s cousin, Kirigami, which allows it to cut, fold, unfold, and move Origi’s materials.
The team’s paper, “Electronically Configurable Microscopic Metasheet Robots,” was published on September 11. Natural materials. The paper’s co-authors are postdoctoral researchers Ching-Kun Liu and Wei Wang. The project was led by physics professor Yitai Cohen, whose lab has previously produced microrobot systems that can actuate limbs, pump water through artificial cilia, and walk autonomously.
In a sense, the origins of the Kirigami robot were inspired by “creatures that can change shape,” Ryu said. “But when people make robots, once they’re made, they can move their limbs, but their overall shape is usually fixed. That’s why we made the metasheet robot. ‘Meta’ means metamaterial, meaning that it’s made up of many components that work together to give the material mechanical motion.”
The robot is a hexagonal tiling of about 100 silicon dioxide panels, each about 10 nanometers thick, connected by more than 200 actuated hinges. When activated electrochemically via external wires, the hinges form mountain and valley folds, unfolding and rotating the panels, allowing the robot to change its range of applications and locally expand and contract by up to 40 percent. Depending on which hinges are activated, the robot can adopt different shapes, potentially wrapping itself around other objects, and then unfolding back into a flat sheet.
Cohen’s team is already thinking about the next step for metasheet technology. They envision combining flexible mechanical structures with electronic controllers to create ultra-responsive “elastic” materials with properties never before possible in nature. Applications could range from reconfigurable micromachines to miniaturized biomedical devices and materials that can respond to shocks approaching the speed of light rather than the speed of sound.
“Because the electronics in each individual building block can harvest energy from light, we can design the material to respond in a programmed way to different stimuli. Instead of deforming when stimulated, these materials might ‘run away’ or push back with a greater force than they were used to,” Cohen said. “We think that these active metamaterials—these elastic materials—could form the basis for a new class of intelligent materials governed by physical principles that go beyond what is possible in the natural world.”
