Nanowires harnessing the power of a human heartbeat to charge smartphones with kinetic energy? It could happen within a decade--the technology need only grow smaller. An electronic chip powered by the ear? We're already there. As reported by The Verge, an MIT research project has tapped into the electrochemical signal that travels between the ear and the brain, siphoning off a tiny portion of that power to run an embedded chip.
The concept is simple. As an eardrum vibrates, that mechanical force is turned into an electrochemical signal by the ear and transmitted to the brain, which interprets what you're hearing. MIT explains that the cochlea houses a "biological battery" that produces that current:
...the battery chamber is divided by a membrane, some of whose cells are specialized to pump ions. An imbalance of potassium and sodium ions on opposite sides of the membrane, together with the particular arrangement of the pumps, creates an electrical voltage.
Although the voltage is the highest in the body (outside of individual cells, at least), it’s still very low. Moreover, in order not to disrupt hearing, a device powered by the biological battery can harvest only a small fraction of its power.
The MIT team implanted a chip with an ultra low-power radio transmitter in the ear of a guinea pig and were able to power it off that biological battery. But it wasn't easy: since the chip can only draw on a fraction of power without disrupting hearing, it builds up charge in a capacitor and can take up to four minutes to produce enough charge to power the radio.
The radio transmitter is the whole point, of course. With it, the chip could eventually be used to "monitor biological activity in the ears of people with hearing or balance impairments, or...deliver therapies themselves." To get there, the chip will have to be viable for human ears--guinea pigs are just a start. Achieving that could have major repercussions for future hearing aids and studies on hearing loss, allowing us to better understand and possibly fix damage to our ears.