Researchers at MIT have, for the very first time, successfully accessed a biological power source that has been known to exist for several decades. That source is located in the inner ear's cochlea where it provides sufficient current to power an electrochemical signal that originates in the vibration of the eardrum. That mechanical force is converted to a signal that is sent to and processed by our brain.
The cochlea serves as a natural battery chamber filled with ions. There have been ideas to tap this "battery", but scientists did not have a feasible concept to actually do so previously.
"In the past, people have thought that the space where the high potential is located is inaccessible for implantable devices, because potentially it’s very dangerous if you encroach on it," said Konstantina Stankovic, an otologic surgeon at the Massachusetts Eye and Ear Infirmary (MEEI). "We have known for 60 years that this battery exists and that it’s really important for normal hearing, but nobody has attempted to use this battery to power useful electronics."
In experiments, Stankovic and her colleagues tested electrodes in guinea pigs’ ears and attached low-power electronic devices to those electrodes. The researcher said that "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."
Key to success was the development of extreme low-power circuits, MIT said. the voltage provided by the cochlea is "very low" and, in order not to impact general hearing, only a fraction of that power can be used for circuits.
Future applications of the technology may include cochlear implants, diagnostics and implantable hearing aids.
There was no information when commercial devices could be ready to take advantage of the discovery.