Scientists have harnessed bio-electrical impulses deep within the human ear to create what they are describing as a “natural battery” that could one day soon be used to power implantable electronic devices without impairing hearing.
Such devices could be used to monitor biological activity in the ears of people with hearing or balance impairments, the effectiveness of treatments, or even be refined to deliver therapies themselves.
In an article published in the journal Nature Biotechnology, researchers — from Massachusetts Institute of Technology, the Massachusetts Eye and Ear Infirmary and the Harvard-MIT Division of Health Sciences and Technology — said studies involving guinea pigs allowed them to tap into electrical signals found deep in the inner ear of mammals.
"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," said Konstantina Stankovic, a surgeon who helped conduct the new experiments. "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."
The new research involved implanting electrodes in the biological batteries in guinea pigs' ears that were attached to low-power electronic devices. 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.
Researchers explained that the ear converts 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.
The research was funded, in part, by the National Institute on Deafness and Other Communication Disorders.