The idea proposed by reseachers at the University of Michigan is to harvest the energy released by a heartbeat to power the pacemaker regulating the same heart:
Piezoelectric materials generate an electric charge when their shape is changed. They are used in some microphones to convert vibrations into an electrical signal.
Researchers at the University of Michigan are trying to use the movement of the heart as a source of electricity.
In tests designed to simulate a range of heartbeats, enough electricity was generated to power a pacemaker. The designers now want to test the device on a real heart and build it into a commercial pacemaker.