A tiny self-propelled drug-delivery device might someday make taking antibiotics safer and more efficient. Think of it as a tiny submarine scooting around inside your stomach, fueled by the acid there. The swallowable device reacts with stomach acid release of tiny hydrogen bubbles. The bubbles scoot it around the stomach, and a magnesium core reduces acidity as it goes. The tiny device is covered by a special polymer, like a jacket, that is sensitive to changes in the acidity. Once the acid in the stomach is neutralized, the polymer dissolves and the submarines unload their antibiotic payload.
http://health.wusf.usf.edu/post/tiny-submarine-cruises-inside-stomach-deliver-drugs#stream/
