Robot-in-a-Capsule to heal stomach wounds

                Scientists have created a tiny origami robot that can unfold itself from a swallowed capsule and crawl across the stomach wall to patch a wound. In the experiments, the robot was to pick up a button battery lodged inside a synthetic stomach and oesophagus model. “It’s really exciting to see our small origami robots doing something with potential important applications to health care,” said researchers.

                “For application 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.” said researcher. The robot can propel itself by using “stick-slip” motion, in which its appendages stick to a surface through friction when it executes a move, but slop free again when irs body flexes to change its weight distribution.

                It consists of two layers of structural material sandwiching a material that shrinks when heated. A pattern of slits in the outer layers determines how the robot will fold when the middle layer contracts. The robot’s envisioned use also dictated a host of structural modifications over an earlier origami robot built by the researchers. Stick-slip only works when, one, the robot is small enough and, two, the robot is stiff enough. However, because the stomach is filled with fluids, the robot does not rely entirely on stick-slip motion.

                20% of forward motion is by propelling water thrust and 80% is by stick-slip motion. In this regard, researchers actively introduced and applied the concept and characteristics of the fin to the body design, which we 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 action on the robot had to be strong enough to cause it to fully unfold. The researchers tested about a dozen different possibilities for the structural material before settling on the type of dried pig intestine used in sausage casings.