The biological eye is a highly complex organ, and people have spent decades trying to replicate this most delicate organ through technology. Existing prosthetic eyes fall short with low-resolutions and 2D flat image sensors.
Now, an international team of researchers at the Hong Kong University of Science and Technology (HKUST) and the University of California, Berkley, have overcome this shortcoming by making, for the first time, a biomimetic prosthetic eye using a nanowire array that creates a hemispherical artifical retina. I.e., a 3D image sensor.
Publishing in Nature, (paywall) the team at HKUST showcase their “Electrochemical Eye” (EC-Eye). Whilst holding great promise in the field of robotics and for people with visual impairments, in perhaps more tantalizing future applications, the team believes their EC-Eye may actually offer sharper vision than a natural human eye, and include extra functions such as the ability to detect infrared radiation in darkness. This of course is stepping into the realm of transhumanism, and the ethical quagmire this entails. But apart from exciting fans of science fiction, the EC-Eye most certainly has more immediate promise for those whose natural vision is severely impaired.
The key to this new artificial eye is the nanowire array mentioned above. These nanowires are derived from perovskite solar cell technology, and are essentially individual nano-solar cells, and can therefore mimic biological photoreceptors found in the retina. These nanowires were then connected to a bundle of liquid-metal wires, serving as artificial nerves, which successfully channeled the light signals to a computer screen which showed what the nanowire array could “see”.
With electronic-to-nerve interfaces research already well under way, it is hoped that one day these nanowire retinas could be directly implanted and attached to the optic nerves of visually impaired patients. More astonishing still, is that this artificial retina is superior to a natural retina when it comes to the shortcomings that have arisen out of the evolution of the natural retina. All retinas have a blind spot, caused by the fact the bundles of optic nerves have to connect somewhere on the retina to transport information to the brain. This connection point on the retina has no space for photoreceptor cells, and is therefore a blind spot on the retina. Thankfully, your brain “fills in the blanks” of this blind spot so that people with healthy vision don’t see it. However, the effects of this blind spot can be seen if you like to look up at the stars at night. Find a very dim star, and try to look at it directly; it becomes hard to see, but it’s easier to see if you instead look directly around it.
The EC-Eye does not have such a blind spot.
Furthermore, the nanowires are higher in density than the photoreceptor cells in the human retina. Therefore, in theory, the artificial retina can detect more light signals and therefore produce a higher image resolution than even the most healthy retinas of a human with twenty-twenty vision.
The advantages of an EC-Eye over a natural eye are also the fact that using different materials can enable the detection of a higher spectral range, potentially allowing people with such EC-Eye implants to see in the dark, if their artificial retina can detect infrared light.
However, the authors caution that this technology is still in its early stages.
“I have always been a big fan of science fiction,” said Prof. Zhiyong Fan of HKUST in a press release, and lead author of the study, “and I believe many technologies featured in stories such as those of intergalactic travel, will one day become reality. However, regardless of image resolution, angle of views or user-friendliness, the current bionic eyes are still of no match to their natural human counterpart. A new technology to address these problems is in urgent need, and it gives me a strong motivation to start this unconventional project.”