So these people have developed a tiny implantable device that generates electrical current when it's bent back and forth, turning the energy of motion into electricity.
So not only could you recharge a cell phone with the movement of your limbs (if the device were implanted into your clothes) but also you could recharge a pacemaker battery with the movements of your lungs and diaphragm.
The technology is similar to these little lights placed on the ends of airplane wings that charge up by the vibrations of the wings in flight.
Again similar to technology where larger devices are placed under or within sidewalks and the mechanical energy of millions of footstep-vibrations power overhead lights in subways and what not.
Could the vibrations of passing traffic in a busy intersection power the LED lights in traffic signals?