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An ingestible origami robot designed to patch wounds, deliver medicine or remove foreign objects from a person's stomach has been developed by researchers from MIT, the University of Sheffield and the Tokyo Institute of Technology.

The robot is swallowed in a capsule and unfolds once in the stomach as its container dissolves. Unlike its creators' previous ingestible robots, the new device is made largely of meat in the form of a type of dried pig intestine used in sausage casings.


In a video demonstration of the robot's capabilities, the team uses a mock-up of a stomach, moulded from that of a pig and made of silicone rubber, with a mixture of water and lemon juice to simulate stomach acid. The robot is sent down the oesophagus in a capsule made of ice and tasked with removing a button battery that's become embedded in the stomach wall.

In the USA alone, 3,500 button batteries are ingested every year, according to the researchers. While most pass harmlessly through the stomach, some leak, reacting with the stomach's acid, and become embedded in the wall of the stomach. The demonstration shows that the robot can grab an embedded battery and lift it free, allowing both robot and battery to then pass through the stomach and be excreted normally.

The robot is currently controlled using an external magnetic field, although MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) director Daniela Rus said the team plans to add sensors and "redesign the robot so that it's able to control itself without the need of an external magnetic field."

Currently, the robot has a magnet at its centre, which responds to magnetic fields outside the body, allowing it to be rotated in order to steer it. The magnet also allows it to pick up the offending battery in the demonstration.


The robot is built with two layers of structural material – the dried pig intestine – sandwiching a layer of biodegradable wrap called Biolefin, which shrinks when it's heated, allowing it to be compressed like an accordion into an easy-to-swallow form. The robot primarily uses a 'stick-slip' motion, where its appendages cling to a surface, such as the stomach wall, through fiction, but are released when the robot's body flexes.

Because it has to move in liquid, as well, the robot also generates forward motion by moving water. "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," said first author Shuhei Miyashita.

To demonstrate the usefulness of a battery-removing robot, Miyashita presented his colleagues with an unusual practical illustration."Shuhei bought a piece of ham, and he put the battery on the ham," said Rus. "Within half an hour, the battery was fully submerged in the ham. So that made me realise that, yes, this is important. If you have a battery in your body, you really want it out as soon as possible."