text: 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,�? says Rus, who also directs MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL). “For applications 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.�? 
   
   Joining Rus on the paper are first author Shuhei Miyashita, who was a postdoc at CSAIL when the work was done and is now a lecturer in electronics at the University of York, in England; Steven Guitron, a graduate student in mechanical engineering; Shuguang Li, a CSAIL postdoc; Kazuhiro Yoshida of Tokyo Institute of Technology, who was visiting MIT on sabbatical when the work was done; and Dana Damian of the University of Sheffield, in England. 
   
   Although the new robot is a successor to one reported at the same conference last year, the design of its body is significantly different. Like its predecessor, it can propel itself using what’s called a “stick-slip�? motion, in which its appendages stick to a surface through friction when it executes a move, but slip free again when its body flexes to change its weight distribution. 
   
   Also like its predecessor — and like several other origami robots from the Rus group — the new robot 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. 
   
   Material difference 
   
   The robot’s envisioned use also dictated a host of structural modifications. “Stick-slip only works when, one, the robot is small enough and, two, the robot is stiff enough,�? says Guitron. “With the original Mylar design, it was much stiffer than the new design, which is based on a biocompatible material.�? 
   
   To compensate for the biocompatible material’s relative malleability, the researchers had to come up with a design that required fewer slits. At the same time, the robot’s folds increase its stiffness along certain axes. 
   
   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. 
   
   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. The forces applied to the robot are principally rotational. A quick rotation will make it spin in place, but a slower rotation will cause it to pivot around one of its fixed feet. In the researchers’ experiments, the robot uses the same magnet to pick up the button battery. 
   
   Porcine precedents 
   
   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. “We spent a lot of time at Asian markets and the Chinatown market looking for materials,�? Li says. The shrinking layer is a biodegradable shrink wrap called Biolefin. 
   
   To design their synthetic stomach, the researchers bought a pig stomach and tested its mechanical properties. Their model is an open cross-section of the stomach and esophagus, molded from a silicone rubber with the same mechanical profile. A mixture of water and lemon juice simulates the acidic fluids in the stomach. 
   
   Every year, 3,500 swallowed button batteries are reported in the U.S. alone. 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. Miyashita employed a clever strategy to convince Rus that the removal of swallowed button batteries and the treatment of consequent wounds was a compelling application of their origami robot. 
   
   “Shuhei bought a piece of ham, and he put the battery on the ham,�? Rus says. “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.�? 
   
   “This concept is both highly creative and highly practical, and it addresses a clinical need in an elegant way,�? says Bradley Nelson, a professor of robotics at the Swiss Federal Institute of Technology Zurich. “It is one of the most convincing applications of origami robots that I have seen.�? ||||| Researchers from MIT have designed a new ingestible "robot" that could one day be used to patch internal wounds, deliver medicine, or remove accidentally swallowed objects from the stomach. The design consists of a specially folded sheet of dried pig intestine (usually used in sausage casing) and a tiny magnet. Folded up, this capsule can be swallowed by a patient. It then hits the stomach and unfolds in the acidic juices, where it can be guided to complete certain tasks using external magnets. 
   
   The design is very much a work-in-progress, but its creators think it offers a promising model for the future. Daniela Rus, the director of MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and co-creator of bot, said it could be useful in health care one day. "For applications inside the body, we need a small, controllable, untethered robot system," said Rus in a press release. "It’s really difficult to control and place a robot inside the body if the robot is attached to a tether." 
   
   The origami capsule could be used to remove swallowed batteries from the stomach 
   
   It's also difficult to steer something precisely around the body using only external magnets, but Rus had a relatively simple first task for the robot: removing a swallowed battery from the stomach. MIT says that every year in the US there are more than 3,500 reports of swallowed batteries. If left in the stomach or esophagus these can burn the tissue. The researchers suggest that the origami meat robot could be deployed in these scenarios to find the magnet, pulling it free from the tissue and guiding it toward the colon for evacuation. 
   
   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. They filled the model with water and lemon juice to mimic the acidic fluids of the stomach, and carried out test runs, finding and removing a battery using their origami bot. 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." Maybe they'll design a vegan version, too. ||||| Enlarge Image Melanie Gonick/MIT 
   
   A pill that unfolds into a little robot could one day give parents everywhere a little more peace of mind. Once swallowed, it can open up inside a person's stomach, crawling across the stomach wall to retrieve a single-cell button battery, and even patch wounds. 
   
   This is no small thing. 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. Although most of these batteries are safely digested, sometimes they can leak and cause tissue burns, bleeding, and death. 
   
   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. 
   
   An ingestible robot, however, poses some significant challenges. 
   
   "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." 
   
   The robot has a magnet attached, and its movements are controlled using magnetic fields that are applied externally. 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. Slits in the two outer layers allow the robot to fold like a small concertina when the inner material contracts. 
   
   This allows it to move along a surface a little like an inch worm. 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. 
   
   And, because stomachs contain liquid, the robot can swim, too. 
   
   "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. 
   
   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. 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 really exciting to see our small origami robots doing something with potential important applications to health care," Rus said. 
   
   The team will be presenting their research at the IEEE International Conference on Robotics and Automation in Stockholm, Sweden that runs from May 16-21.
target: – 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.)