cylonlover writes "Our ears work by converting the vibrations of the eardrum into electrochemical signals that can be interpreted by the brain. The current for those signals is supplied by an ion-filled chamber deep within the inner ear – it's essentially a natural battery. Scientists are now looking at using that battery to power devices that could be implanted in the ear, without affecting the recipient's hearing. The 'battery chamber' is located in the cochlea. It is internally divided by a membrane, some of the cells of which are designed to pump ions. The arrangement of those specialized cells, combined with an imbalance of potassium and sodium ions on opposite sides of the membrane, are what creates the electrical voltage. A team of scientists from MIT, the Massachusetts Eye and Ear Infirmary, and the Harvard-MIT Division of Health Sciences and Technology have recently succeeded in running an ultra-low-power radio-transmitting chip using power from these battery chambers – in guinea pigs' ears."