The miniature bots could have the potential to carry out different types of surgery – like patch wounds, remove objects and take samples.
Researchers at MIT, the University of Sheffield, and the Tokyo Institute of Technology have demonstrated a tiny origami robotA that can unfold itself from a swallowed capsule and, steered by external magnetic fields, crawl across the stomach wall to remove a swallowed button battery or patch a wound.
But because the stomach is filled with fluids, the robot doesn't rely entirely on stick-slip motion. "In our calculation, 20 percent of forward motion is by propelling water — thrust — and 80 percent is by stick-slip motion," says Miyashita. "In this regard, we actively introduced and applied the concept and characteristics of the fin to the body design, which you can see in the relatively flat design."
It also had to be possible to compress the robot enough that it could fit inside a capsule for swallowing; similarly, when the capsule dissolved, the forces acting on the robot had to be strong enough to cause it to fully unfold. Through a design process that Guitron describes as "mostly trial and error," the researchers arrived at a rectangular robot with accordion folds perpendicular to its long axis and pinched corners that act as points of traction.