Not too long ago the idea of artificial vision was little more than science fiction. The concept has been portrayed time and time again in movies and on T.V. From the cyclopean eye of the HAL 9000 in Stanley Kubrick's epic 2001: A Space Odyssey to the visor of Geordi La Forge in Star Trek, the idea of being able to enhance machines and return sight to the blind has captured our imagination for decades.However, mimicking human vision, a sense that took nature millions of years to perfect, is no easy task. In the year 2000 a man was fitted with the first functional electronic eye. A camera sent images to a brain implant, via a computer, allowing the man, identified only as Jerry, to perceive black objects against white backgrounds. Composed of a mere hundred sensors, this limited vision allowed Jerry to discern a two inch tall letter E and navigate the New York subway. A useful visual aid perhaps, but not yet approaching the sophistication of human vision.
One of the major stumbling blocks in the quest for artificial vision is the shape of the retina, the light sensitive inner layer of the eye. The retina contains millions of photoreceptors which capture light and transmit it as electrical signals along the optic nerve to the brain. In animals the retina is curved in order to better sense the 3D world in which we live. Until recently however, scientists were unable to place such a large number of artificial photoreceptors on a curved surface. Now, new research may point the way to true artificial sight.
Scientists at the University of Illinois and Northwestern University have constructed a device which weaves a network of photoreceptors into a flexible mesh. The mesh is laid across a curved rubber membrane to produce a device roughly the size and shape of a human eye. "This approach allows us to put electronics in places where we couldn't before," said Professor John Rogers, who led the research group. Up until now artificial vision systems have been limited by flat silicon based image sensors. Silicon is brittle and shatters when bent, restricting cameras and other imaging equipment to flat receptors, which distort images.
Professor Rogers and Professor Yonggang Huang overcame these limitations by linking tiny silicon light sensors together with minute flexible wires that are capable of bending by up to 40 percent. A curved array of detectors is "much better suited for use as retinal implants," Rogers said.
It's hoped that the breakthrough research, which was published in the science journal Nature, will herald the advent of new classes of imaging devices and work is already underway to examine other potential applications for the technology.
