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...