A Retinal Prosthetic Powered by Light: The device, designed by researchers at Stanford University in Palo Alto, California, combines infrared video-projection goggles with a small, wire-free chip implanted inside the retina.
A camera on the goggles transmits video to an image processor, which sends a signal back to infrared projection screens inside the goggles. Other researchers have tried to develop photovoltaic retinal implants in the past, but it didn't work. "The light that you get into the back of the retina at the equator on a sunny day is not enough to power a retinal implant," says James Loudin, a researcher at Stanford. So the Stanford system doesn't rely on the light that comes into the eye; it uses a projection system to make much more intense signals...
The infrared image is picked up by a compact array of photovoltaic pixels implanted right where the light-sensing cells would be in a healthy eye. Each pixel contains three infrared-sensitive diodes facing the inside of the eye. The diodes convert light into electricity that's pulsed out to the nerve cells by electrodes facing the back of the eye.
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