The laser-based approach differs significantly from conventional cochlear implants, which use electric fields to stimulate auditory nerves. The problem with this method is the challenge of stimulating a single auditory nerve in the cochlea, due to the fact that the auditory portion of the inner ear is tiny and crams lots of nerves into a closed space — meaning-less focused electric fields, and worse sound quality. Lasers, on the other hand, are much more efficient at targeting specific areas of the ear.
“[We’ve built] a prototype of a cochlear implant based on opto-acoustic stimulation,” Dr. Mark Fretz, a physicist and project manager at the wiss Center for Electronics and Microtechnology, told Digital Trends. “We use laser light in the infrared range to generate a sound wave in the fluid inside the cochlea. The process is somewhat similar to the thunder following lightning. In both cases, the sound is the result of rapidly heated fluid, with the distinction that in our device the light is actually generating the sound by heating up the liquid, whereas in the case of the lightning, a strong electric current quickly heats up the air, consequently generating both the light and the thunder.”
Over the past three years, the team has demonstrated its theories about using laser light to stimulate auditory nerves using guinea pigs. They have also created a device (not yet tested in vivo), comprising a palm-sized box containing the necessary electronics components and two ultrathin implantable lasers.
Going forward, the main challenges are to turn this into a finished product, while finding a way to deal with the issue of energy consumption, as well as increasing the number of lasers per device and looking at different stimulation patterns.
Should all go to plan, however, it may not be long before focused laser light is a crucial part of helping people who are deaf or hard of hearing to register sound again.
