In experiments involving a simulation of the human esophagus and stomach, researchers at MIT, the University of Sheffield, and the Tokyo Institute of Technology have demonstrated a tiny origami robot 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. The new work, which the researchers are presenting this week at the International Conference on Robotics and Automation, 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. "It's really exciting to see our small origami robots doing something with potential important applications to health care," Rus said. Developed by an international team of researchers from MIT, the University of Sheffield in the UK and the Tokyo Institute of Technology in Japan, the origami robot is the latest developed by MIT Computer Science and Artificial Intelligence Laboratory director Daniela Rus, who has been building and researching origami robots for years. "For applications inside the body, we need a small, controllable, untethered robot system," Rus explained in a statement. It’s really difficult to control and place a robot inside the body if the robot is attached to a tether.�? It uses what the team calls a "stick-slip" motion, whereby its pointed corners, designed for traction, will stick to surfaces using friction when it moves, but then slip free when the robot flexes. Slits in the two outer layers allow the robot to fold like a small concertina when the inner material contracts. "In our calculation, 20 percent of forward motion is by propelling water -- thrust -- and 80 percent is by stick-slip motion," said first author Shuhei Miyashita, formerly a postdoc at CSAIL, now a lecturer in electronics at the University of York in the UK. In the center of one of the forward accordion folds is a permanent magnet that responds to changing magnetic fields outside the body, which control the robot’s motion. When deployed in this environment in a capsule made of ice that melts in the warm environment, the robot made its way to a button battery and picked it up using its attached magnet. It's constructed of two layers of structural material that maintain the robot's shape, sandwiching a layer of material made from dried pig intestine (the kind used in sausage casings) that shrinks when heat is applied. To assess the robot's suitability for this task, the scientists bought a pig's stomach and modeled a cross-section of it using silicon. The team built a synthetic stomach out of silicone rubber, modelled on the mechanical properties of a pig's stomach, and filled it with a mixture of water and lemon juice to simulate stomach fluids. In the US every year, over 3,500 incidents of swallowed button batteries are reported in the US, and most cases of battery swallowing involve toddlers. Frequently, the batteries are digested normally, but if they come into prolonged contact with the tissue of the esophagus or stomach, they can cause an electric current that produces hydroxide, which burns the tissue. The next step, says Rus, is to "add sensors to the robot and redesign [it] so it's able to control itself without the need of an external magnetic field."
– The stat is remarkable: Every three hours in the US, a child swallows a battery and risks potentially lethal consequences, per the Washington Post. Now, however, a clever fix is in sight, thanks to origami. MIT researchers have unveiled a tiny robot that, once ingested, unfolds inside the body to retrieve batteries or other foreign objects. They've demonstrated how it works in a synthetic stomach, with tests on live animals on deck. Research on the device is still in the early stages, but it could theoretically be used to patch wounds inside the stomach as well, the scientists say in a press release. "It's really exciting to see our small origami robots doing something with potential important applications to health care," says MIT's Daniela Rus. The Post notes that the robot's structural material had to be highly safe, meaning "sharp chips" were out. "We spent a lot of time at Asian markets and the Chinatown market looking for materials," says one researcher, and they ended up going with dried pig intestine. (The Verge wonders about a vegan version.) The robot is encapsulated in ice; upon being swallowed and melting, it opens up to move along like an "inch-worm," explains CNET. Scientists are able to control its movement via magnetic fields, and it can "swim" in the stomach's fluids—"20% of [its] forward motion is by propelling water," per the release. In the demonstration, the robot's attached magnet allowed it to latch onto a battery and remove it. (The concept of origami holds the promise of creating inexpensive robots.)