Cochlear implants have helped over a million people worldwide by providing a sense of sound to those who are deaf or hard of hearing.
However, these devices currently require external hardware, which can be cumbersome and limit activities like swimming, exercising, or even sleeping.
A team of researchers from MIT, Massachusetts Eye and Ear, Harvard Medical School, and Columbia University is working on a game-changing solution: an implantable microphone that could make cochlear implants fully internal.
This new microphone performs as well as commercial external hearing aid microphones, overcoming one of the biggest obstacles to fully internal cochlear implants.
The innovative microphone is made from a special piezoelectric material that generates an electric charge when it moves.
This tiny sensor, called the UmboMic, measures minuscule vibrations on the underside of the eardrum.
To ensure the best performance, the team also created a low-noise amplifier to enhance the signal without adding extra noise.
Developing this implantable microphone wasn’t easy. The sensor needed to be biocompatible, meaning it wouldn’t harm the body, and it had to withstand the body’s humid environment.
The UmboMic, about the size of a grain of rice, is designed to be placed against the umbo, a part of the middle ear that vibrates with sound.
The researchers used a clever design to reduce noise: the sensor’s layers produce opposite charges when bent, and by taking the difference between these charges, they cancel out the noise.
However, working with the piezoelectric material was tricky because it loses its properties at high temperatures, which are needed to apply other materials to it.
The team solved this by cooling the sensor during the process.
Testing the UmboMic in human ear bones from cadavers showed that it could effectively pick up sounds within the range of human speech. The microphone and amplifier together can distinguish very quiet sounds from background noise.
The team is now preparing to test the UmboMic in live animals to see how it works when implanted.
They are also exploring ways to package the sensor so it can last in the body for up to 10 years while remaining flexible enough to capture vibrations. Traditional packaging materials like titanium would be too rigid, so they need to find alternatives.
This research, funded by organizations including the National Institutes of Health and the National Science Foundation, shows great promise.
If successful, the fully internal cochlear implant could significantly improve the quality of life for people with hearing loss, allowing them to enjoy more activities without the limitations of external hardware.
Source: MIT.
