Have you ever wondered how the mechanical forces of sound was converted into a signal your brain can understand? Within the ear is the cochlea which contains a chemical battery; a membrane separating two ion-containing fluids. When needed, the membrane pumps ions from one side to the other, creating an electric potential to signal the brain. Now researchers at MIT, the Massachusetts Eye and Ear Infirmary, and the Harvard-MIT Division of Health Sciences and Technology have developed an implant that can draw on that battery for power.
Obviously the challenge for creating such an implant is making sure it uses so little power that the subject's hearing is not disrupted. This required using an ultra-low power antenna and control circuits, but even then, there was not enough power. To address that the researchers added a capacitor that builds up the charge needed for operation over time. The circuitry was also designed in such a way that once it got enough power to start operating, it would be able to keep operating, with the limited energy from the battery.
The potential of this implant is quite impressive as it could be used to drive hearing aids and diagnostic systems for monitoring the health of the inner ear. It is even possible that such an implant could deliver some kind of therapy to the ear when needed.