Scientists at the University of Illinois at Urbana-Champaign have develop a tiny, patch-like battery that uses the natural movement of organs, like the heart or lungs, to generate electricity inside the human body. The device works on the principle of piezoelectricity, where a metal or metal composite generates electricity under mechanical stress. The device is made up of a metal nanoribbion embedded in an ultra-thin, flexible material that clings to the surface of an organ. The scientists say it generates more electricity than needed by conventional implants like pacemakers or nerve stimulators. The scientists are currently testing out the reliability and safety of long-term use of the battery.