Researchers at MIT, the University of Sheffield, and the Tokyo Institute of Technology have showed a small origami robot that can unfold itself from a swallowed capsule and creep across the stomach wall to remove a swallowed button battery or patch a wound.

The new work builds on a long sequence of papers on origami robots from the research group of Daniela Rus, the Andrew and Erna Viterbi Professor in MIT’s Department of Electrical Engineering and Computer Science.

Rus said: "For applications inside the body, we need a small, controllable, untethered robot system.

"It’s really difficult to control and place a robot inside the body if the robot is attached to a tether."

The new robot features two layers of structural material sandwiching a material that shrinks when heated.

A pattern of slits in the outer layers decides how the robot will fold when the middle layer contracts.

It will use a stick-slip motion, in which its appendages stick to a surface through friction when it executes a move, but slip free again when its body flexes to change its weight distribution.

The robot doesn’t rely entirely on stick-slip motion, as the stomach is filled with fluids.

The researchers had to come up with a design that required fewer slits to compensate for the biocompatible material’s relative malleability.

Image: An example of a capsule and the unfolded origami device. Photo: courtesy of Melanie Gonick/MIT.