Scientists built a swallowable paper battery to power medical devices

Researchers created a paper battery that powers devices inside the body and gradually dissolves afterward. In pig tests it ran for up to three days, delivering 1.77–1.84 V and up to 3.5 mAh.

• The battery uses a magnesium anode, molybdenum trioxide cathode and cellulose nanofibrils
• The small version fits a gelatin capsule and delivers 1.77 V and 2 mAh/cm²
• A beeswax coating slows degradation in stomach acid
• In pigs it powered an RFID tag and a capsule that stimulated the stomach