A friend of mine was given a pacemaker years ago. While he was grateful for the lifesaving device, he kept telling everyone that he would eventually have to replace the batteries by having a dangerous or complicated operation.
We didn’t know if we should be happy or sad for him. That conundrum may soon be gone forever, now that engineers at Dartmouth College said they have invented “a dime-sized piece of kit that turns the kinetic energy of the heart into electricity that could power a range of implantable devices.”
I’m not exactly sure how to explain this advancement, so I am quoting a post that appeared in Engadget.
They said, “By adding a thin piece of polymer piezoelectric film, called ‘PVDF,’ to existing devices, such as pacemakers, it converts even the smallest motion into electricity, as well as ‘recharging’ an implanted device, the same modules could also be used as sensors to collect real-time health data on patients.” That could possibly mean no more scary operations to recharge internal batteries.
DigiDame 
What a great idea.Surprising it took so long to come up with.