Researchers from University of Michigan announced that they have developed a new device that could power an implanted pacemaker

Amin Karami, who is with the university’s Department of Aerospace Engineering, said that the device makes use of the ambient vibrations of the heart beat which briefly expands a special “piezoelectric” ceramic material and converts it into electricity.
The researchers said that the amount of power generated by the device is eight times more than what is needed to operate a typical implanted pacemaker. “The idea is to use ambient vibrations that are typically wasted and convert them to electrical energy. If you put your hand on top of your heart, you can feel these vibrations all over your torso”, Karami said.
Source-Medindia