"One of the main constraints [of the swallowable imaging capsule] is the battery," says Milan Dodig, a gastroenterologist at Cleveland Clinic, who uses the device to treat his patients. "It takes almost 60 percent of the volume of the capsule; it's not steerable [and] can still miss stuff. The angle of the images is also limiting, and you can't see the complete [intestine]."

The ETH team was able to detect how well modules linked together by monitoring changes to the field of each magnet. "With [this] simple method, I can detect if one is connected, which means I can create a picture on the computer," says Nagy.

The next stage of the research will involve making sure that the magnets do not harm tissue when they lock together. This will involve testing the system in a moving artificial stomach or an animal stomach provided by a partner group. The team also needs to find a way to control how the capsules arrange themselves.

"Something like this that could be swallowed, self-assembled, and remotely controlled would be a major advance," says Joseph Murray, a gastroenterologist at the Mayo Clinic, who was not involved in the work. However, he says that it will be a challenge to use the magnets safely.

"There is a large demand from physicians to have a steerable, motion-controlled camera," adds Frank Volke, a project leader at the Fraunhofer Institute for Biomedical Engineering, in Sankt Ingbert, who is helping to develop a technique for steering Given Imaging's pill camera by magnetically controlling it. "I think it is a very interesting scientific research approach which might take longer for practical use," Volke says of the ETH work.

Nagy says that the magnetic linking scheme developed by his team could also be used to build search-and-rescue robots that can slither through rubble and into tight spaces. "You can imagine throwing in a couple of pieces of the robot and it self-assembling," says Nagy.