Using the Inner Ear's Biological Battery

Scientists have harvested energy from a guinea pig's inner ear and used it to power a small wireless transmitter. With further design work, researchers could harvest this biological battery to power implanted devices near the human ear, such as molecular sensors and drug delivery vehicles for hearing loss and other disorders, according to a study to be published today in Nature Biotechnology.

It has been known for decades that the inner ear contains this biological battery, but until now, no one has harvested it. The authors of the paper, led by Anantha Chandrakasan at Massachusetts Institute of Technology and Konstantina Stankovic at Massachusetts Eye and Ear Infirmary, succeeded without damaging the guinea pigs' hearing. 

http://spectrum.ieee.org/tech-talk/biomedical/devices/using-the-inner-ears-biological-battery