Innovation
Low-power chip keeps cochlear implants out of sight
By using the ear as a natural microphone, this new cochlear implant doesn't require any external hardware.
Now, MIT researchers have developed a low-power signal-processing chip, which could lead to a cochlear implant that doesn’t require any exterior hardware.
Rather than use an external microphone to gather sound, the new implant would use the natural microphone of the middle ear. Okay, a quick anatomy lesson, from the MIT News Office:
Delicate bones in the middle ear, known as ossicles, convey the vibrations of the eardrum to the cochlea, the small, spiral chamber in the inner ear that converts acoustic signals to electrical. In patients with middle-ear implants, the cochlea is functional, but one of the ossicles -- the stapes -- doesn’t vibrate with enough force to stimulate the auditory nerve.
A middle-ear implant uses a tiny sensor to detect vibrations of the ossicles and an actuator to drive the stapes accordingly. The new cochlear implant would use the same type of sensor, but the signal generated travels to a microchip implanted in the ear -- which then converts it to an electrical signal, passing it on to an electrode in the cochlea.
To do away with the skull-mounted hardware, the team had to lower the power requirements of the converter chip. MIT News explains:
The key was to specify a new waveform -- the basic electrical signal emitted by the chip, which is modulated to encode acoustic information -- that is more power-efficient to generate but still stimulates the auditory nerve in the appropriate way.
The implant would be wirelessly recharged and could run for about eight hours on each charge. The researchers also have a prototype charger that plugs into a cellphone and can recharge the chip in two minutes.“The idea with this design is that you could use a phone, with an adaptor, to charge the cochlear implant, so you don’t have to be plugged in,” says study coauthor Anantha Chandrakasan of MIT. “Or you could imagine a smart pillow, so you charge overnight, and the next day, it just functions.”
The work was presented at the International Solid-State Circuits Conference this week.
[Via MIT News Office]
Image: cochlea from Gray’s Anatomy via Wikimedia
This post was originally published on Smartplanet.com