Scientists built a swallowable paper battery that can power medical devices inside the body and then gradually break down after its job is done.So far, the battery has been tested only in pigs, in which it powered devices for up to three days. If proven safe and effective in people, the battery could someday power temporary devices inside the gut while avoiding surgery to retrieve a conventional battery from the body when the device is no longer needed."I'm very excited about this work," said Reza Ghodssi, a professor of electrical and computer engineering at the University of Maryland who was not involved in the study. "The battery is one component that takes up most of the space in an inge...