Minuscule MIT Implant Powered By Ear’s Biological Battery

Our pockets and backpacks are full of technology that would barely fit inside a room a few short decades ago. As technology becomes more efficient, the gadgets we love and depend on continue to shrink. The ability to create powerful devices that can fit in tiny spaces allows technology to solve problems in ways that would have been dangerous or logistically impossible in the past.

For many years, scientists have been aware of a biological battery buried deep within our own auditory system. The ear converts a mechanical force — the vibration of the eardrum — into an electrochemical signal that can be processed by the brain; the biological battery is the source of that signal’s current. Although experts have long wondered if this battery might be able to power a tiny hearing implant, such a procedure was seen as too risky. Always up for a challenge, the scientists at MIT wanted to prove that today’s technology was up to the task. They created a tiny chip that’s powered by the ear’s own electrical plant without affecting hearing.

MIT Ear Implant on a Penny

Image via Patrick P. Mercier/MIT

For the study, published in the most recent edition of Nature Biotechnology, researchers implanted electrodes in the biological batteries of a guinea pig’s ears. Attached to the electrodes were low-power electronic devices developed by MIT’s Microsystems Technology Laboratories. After the implantation, the guinea pigs responded normally to hearing tests, and the devices were able to wirelessly transmit data about the chemical conditions of the ear to an external receiver.

“The fact that you can generate the power for a low voltage from the cochlea itself raises the possibility of using that as a power source to drive a cochlear implant,” said Cliff Megerian, chairman of the otolaryngology department at Case Western Reserve University. “Imagine if we were able to measure that voltage in various disease states. There would potentially be a diagnostic algorithm for aberrations in that electrical output.”
