The 3,500 people who swallow button batteries each year may soon have the option to chase the tiny hazards with origami robots, programmed to push them to the exits.

While most people pass button cell battery with no consequence, there's still a high risk that the foreign object could get lodged in the stomach walls and react with stomach acid to produce hydroxide — and hydroxide burns through tissue.

Shuhei Miyashita, a postdoc at CSAIL at the time, convinced his colleague Daniela Rus that button battery retrieval and internal wound treatment were both compelling use cases for the origami robot, which they'd been working on in collaboration with other researchers from MIT's Computer Science and Artificial Intelligence Laboratory, the University of Sheffield, and the Tokyo Institute of Technology.

"Shuhei bought a piece of ham, and he put the battery on the ham," said Rus, MIT professor and CSAIL director. "Within half an hour, the battery was fully submerged in the ham. So that made me realize that, yes, this is important. If you have a battery in your body, you really want it out as soon as possible."

The team's origami robot is an iteration of previous research done with the concept. However, the latest origami robot differs from its predecessor because it uses biocompatible material — and that material is dried pig intestine, the same type used as casing for sausage.

Like the previous origami robot, the latest one uses a "stick slip" motion to move around the stomach after they've been ingested and have unfolded. The "stick slip" motion leverages the robot's rigidity and friction to stick to a surface, while using its flexibility to "slip" forward.

The robot uses "stick slip" about 80 percent of the time it's moving forward, and propels itself through water the other 20 percent of the time, according to Miyashita.

Right now, the robot is directed to its target via an external magnetic field, but that could change soon.

"Next we would like to do in vivo experiments. We would also like to add sensors to the robot and redesign the robot so that it's able to control itself without the need of external magnetic field," said Rus in the video below.

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