An origami robot that can be swallowed in a pill and sent on missions inside the body promises a revolution in internal treatment of the digestive system, scientists claim.
A team from the Massachusetts Institute of Technology (MIT), Sheffield University, and the Tokyo Institute of Technology trialled the fold-up device in a mock stomach and found it was able to dislodge and remove foreign objects such as batteries.
The researchers also believe the robot could be modified to deliver drugs and perform targeted surgery in otherwise inaccessible regions of the stomach and gut.
The device folds into a pill made of ice, pictured above left. When swallowed, the casing melts and the robot unfolds in the stomach and rolls around the stomach lining, controlled by magnetic fields outside the body.
Approximately 3500 batteries are accidentally swallowed in the US each year, according to the research team.
Although the batteries are often digested normally, if they come into prolonged contact with the tissue of the oesophagus or stomach they can cause an electric current that produces hydroxide and burns a hole in the tissue. Small and circular lithium batteries are a particular risk for small children.
The NHS holds no specific figures on the number of UK cases, but swallowing batteries is known to have caused the deaths of some children.
In trials conducted by the MIT-led team, the robot rolled towards the lithium battery before attaching itself. With the help of external magnets, the robot was then able to drag the battery away.
The scientists say the robot, and any foreign objects it is tasked with removing, can leave the body by being dragged towards the gut where it can be passed naturally.
"It's really exciting to see our small origami robots doing something with potential important applications to healthcare," said Daniela Rus, professor of electrical engineering and computer science at MIT.
Rus said she was initially sceptical about the importance of ensuring the robot could remove batteries until Shuhei Miyashita, now a lecturer at York University, gave her a crude demonstration.
"Shuhei bought a piece of ham and he put the battery on it," she said.
"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."
The robot is made from the same type of dried pig intestine used in sausage casings. Rus said the ultimate aim was to develop sensors on the device so it could perform tasks automatically, without an external controller.
Dr Miyashita said the next stage would be to test the robot in the stomachs of animals such as cows before moving on to human trials.
It is hoped the device will be available for clinical use in six to eight years, he said.