Original source: Physics World
An artificial device that closely mimics the structure and function of the human eye has been unveiled by Leilei Gu and colleagues at The Hong Kong University of Science and Technology. The team based its design around a hemispherical arrangement of light-sensitive nanowires, which imitate photoreceptor cells in the human retina. Their device has the potential to produce images at higher resolutions than the human eye and could lead to significant new advances in robotics.
Our eyes provide us with around 80% of the information we perceive from our environment. They give us a field of view as wide as 160°; quickly adapt to different lighting and visibility conditions; and resolve details as small as 30 cm from 1 km away. This is possible thanks to our retinas – concave hemispheres that contain 10 million photoreceptor cells in every square centimetre.
While some other parts of the body have been successfully mimicked by technology, the eye has proven far more difficult to copy. At the heart of the problem are the flat configurations of today’s most advanced image sensors, which make them all but impossible to integrate into hemispherical structures to create artificial retinas.
Gu’s team circumvented this issue by mimicking the eye’s photoreceptor cells using perovskite nanowires, which served as light-sensitive electrodes. The wires were deposited onto the inside surface of a porous, hemispherical shell of aluminium oxide, and attached to liquid-metal wires which simulated the nerve fibres behind the retina.
An opposite-facing, tungsten-coated aluminium hemisphere then acted as the countering electrode to the nanowires; while the space between the hemispheres was filled with an ionic fluid electrolyte, comparable to the vitreous fluid found in human eyes. Finally, a lens and adjustable aperture were placed over a hole in the second hemisphere.
Gu and colleagues have built a prototype of their design with a nanowire arrangement that creates 100 pixels – enough to reconstruct images of different letters projected onto the device’s lens. Although this is far from the capabilities of the human eye, the researchers calculate that the nanowires they use could be packed in densely enough to allow for images with resolutions ten times higher than those that our eyes produce.
Applications for a fully functional artificial eye could include human-like robots that carry out autonomous tasks and excel at interacting with humans. In addition, the design could inspire the development of prosthetic eyes that entirely reconstruct the sight of visually impaired people. Gu’s team now aims to realize the full potential of their device, and hope to produce biomimetic eyes that outcompete our own eyes in the near future.
The artificial eye is described in Nature.