Life in 3D: 1mm robot folds, flips and moves with just a spark of power

Cornell University researchers have developed a tiny robot, smaller than 1 millimeter, that starts as a flat hexagon but turns into 3D shapes and moves when given an electric charge.

The robot’s flexibility comes from its unique design using Kirigami, a technique similar to Origami in which cuts in the material allow it to fold, expand, and move.

The Kirigami design helps it to stretch from tiny 10 nm hinges to 100 μm panels, forming a robot about 1 mm in size. The panels are arranged in cells that can expand and contract by 40 percent in just 100 milliseconds.

“By overcoming obstacles associated with miniaturization, we demonstrate microscopic electronically configurable morphing metasheet robots,” said the team in the study abstract.

Shape-shifting robot

The Kirigami robot was inspired by living organisms that can change shape. Traditional robots can move limbs but typically maintain a fixed shape.

This new metasheet robot is made from metamaterials, which consist of numerous building blocks that give the material unique mechanical properties not often found in natural materials.

The robot is built from hexagonal tiling with about 100 silicon dioxide panels connected by more than 200 ultra-thin hinges. These panels are arranged in cells that can expand or contract by 40 percent in 100 milliseconds.

With over 200 hinges, the robot can switch between different shapes. By controlling separate regions with precise timing, the robot creates movements to crawl or shift its form.

When electrochemically activated, these hinges create folds that allow the robot to expand, contract, and change shape. It can even wrap around objects and return to its flat form.

“In Origami, if you wanted to create three-dimensional shapes, usually you have to hide the excess material inside the 3D object that you’re making. But with Kirigami, you don’t have to hide anything,” said Itai Cohen, professor of physics at the College of Arts and Sciences, in a statement .

Tiny robot breakthrough

The creation of this microscale machine was a lengthy and complex process, involving tasks like threading electrical wires through various hinges and finding the perfect balance between flexibility and rigidity to allow the robot to form and maintain its shape.

According to the team, one of the biggest challenges was developing a way for a device with so many moving parts to move on its own. “When you have a Kirigami sheet, you have hundreds of potential contact points with the ground.
And so for the longest time, we were confused about which parts of the robot were contacting the ground to make the robot move,” said Jason Kim, a postdoctoral researcher and co-author of the study.

It was discovered that instead of relying on friction, the robot could move more consistently by swimming through its environment by altering its shape. Swimming at the microscale, however, is very different from typical swimming , resembling movement through thick fluid like honey.

By adjusting the robot’s shape so that different parts were closer to the surface at different points during its motion, fluid drag forces could be used to propel the robot forward. This highlights a unique aspect of designing microscopic robots, as the physics of movement at this scale differs significantly from that of larger, macroscopic robots.

The next phase of metasheet technology involves combining flexible mechanical structures with electronic controllers to create ultra-responsive “elastronic” materials with properties not found in nature.

Researchers highlight potential applications that include reconfigurable micromachines, miniaturized biomedical devices, and materials capable of responding to impacts almost at the speed of light, rather than sound.

By integrating electronics that harvest energy from light, these materials could be programmed to react to various stimuli. Instead of deforming when touched, they could “run” away or push back with more force than they received, offering new possibilities for advanced responsive materials.

“We think that these active metamaterials – these elastronic materials – could form the basis for a new type of intelligent matter governed by physical principles that transcend what is possible in the natural world,” said Cohen.

The details of the team’s research were published in the journal Nature Materials .