A group of scientists from the Hong Kong University of Science and Technology developed a prototype of a bionic eye so precise that it even surpasses its human simile in several tests.
The article was published in the journal Nature and details how this device mimics the structure of the human eye, making it more sensitive to light and giving it a faster reaction time than a real eyeball.
“In the future, we can use this to improve vision prosthetics and humanoid robotics,” said engineer and materials scientist Zhiyong Fan of the Hong Kong University of Science and Technology about this artificial eye.
The team in charge of Fan had the biggest challenge that was creating a bionic retina capable of imitating the difficult dome-shaped curvature of the real one. For that, they used a curved aluminum oxide membrane, with nano-sized sensors made of a light-sensitive material called perovskite, which served to mimic that architecture in their synthetic eyeball. Cables connected to the artificial retina send readings from those sensors to external circuits for processing, just as nerve fibers transmit signals from a real eyeball to the brain.
In this way, this robotic eye registers changes in illumination faster than human eyes, within about 30 to 40 milliseconds, instead of 40 to 150 milliseconds. The device can also see dim light, since its 100-degree field of view is not as wide as the 150-degree a human eye can capture, it’s better than the 70-degree visible to ordinary flat-image sensors.
The artificial retina created by Fan has around 460 million light sensors per square centimeter. An actual retina has around 10 million light-detecting cells per square centimeter. 100 of these cables wrap around the back of the bionic retina, creating images that are 100 pixels.
One of the detractors of this technique from the Hong Kong University of Science and Technology is Hongrui Jiang, an electrical engineer from the University of Wisconsin-Madison whose commentary on the study appears in the same issue of Nature. “Working a few hundred nanowires is fine, but how about millions?” Engineers will need a much more efficient way of manufacturing large sets of small cables on the back of the artificial eyeball to give it a superhuman vision, “he concluded.