We can’t argue that cochlear implants have transformed the lives of thousands of people affected by deafness. However, like many medical devices at some point in their existence, the limitations of current technology don’t put cochlear implants at the top of the list in terms of convenience. The primary issues stem from the fact that a good deal of the implant’s circuitry, such as the microphone, processor, and transmitter, are external.
For kids, it makes things inconvenient when doing physical activities, such as swimming (although this fortunately is changing). For adults, having wires coming out of their head isn’t in style (yet), and the implant can give off the perception of being handicapped. On the engineering end of things, the delicate wires that connect the microphone to the transmitter coil are not always designed to withstand the rigors that our heads endure.
Researchers from the University of Utah have succeeded in designing a key component of the cochlear implant that they hope will someday make them more durable and kid-friendly (and fashionable too). The component of interest is the microphone, which picks up sound waves. Cochlear implants need to have the microphone behind the ear or somewhere on the side of the head where there’s a clear path for sound to travel, as sound waves physically vibrate a membrane or diaphragm to generate an electrical signal. The U of U device places the microphone in the middle ear and uses accelerometer technology instead of a membrane to detect sound. Specifically, the device is attached to the umbo (eardrum) and detects its vibrations, which are converted to electrical signals and sent directly to electrodes in the cochlea. In this system, everything formerly external is now implanted into a package currently the size of a pencil eraser; the only visible evidence of a cochlear implant will be the wireless battery charger worn while sleeping.
It’s no small feat, and researchers want to further reduce the size of the device by a third. However, they’re facing challenges in improving the sound quality, as the current output sounds something akin to an AM radio.
Article from the University of Utah: A Middle-Ear Microphone
Study abstract in IEEE Transactions on Biomedical Engineering: MEMS Capacitive Accelerometer-Based Middle Ear Microphone