The human eyes encompass incredible natural abilities, including an exceptionally wide field of view, and high resolution married with low distortion capabilities. Almost impossible to synthetically recreate in their entirety these factors taken together can make the loss of vision or the physical removal of an eye a highly distressing and adaptive life-event.
In situations where the patient’s eyeball must be surgically removed via a technique known as enucleation, there are very limited options, as is the case for some of those people suffering complete vision loss, with patients usually offered an ocular prosthesis for cosmetic purposes. However, historically vision is not restored through the use of these artificial eyes.
The world’s first 3D artificial eye
Now, a study from researchers led by HKUST develops the world’s first 3D artificial eye surpassing the capabilities of pre-existing bionic eyes and in some cases, exceeding those of the human eyes. The team states their electrochemical eye replicates the structure of its natural counterpart to proffer sharper visual acuity in the future, with extra functions such as the ability to detect infrared radiation in darkness. The study is published in the journal Nature.
Previous studies have indicated ocular prostheses mimicking natural eyes are highly desirable, with a view to restoring sight in humans and gifting vision to humanoid robotics. However, the spherical shape and retina of the biological eye pose a mammoth hurdle for biomimetic devices with engineers attempting to replicate the structure and functionality of a biological eye for over a decade.
Existing prosthetic eyes, however, mostly encompass a pair of spectacles attached with external cables, only able to provide flattened 2D vision with poor resolution. Therefore, a new technology to address these problems is urgently needed. The current study manufactures an electrochemical eye comprising a hemispherical retina constructed from a high-density array of nanowires mimicking the photoreceptors found in the human eye.
The current study fabricates a 3D artificial retina consisting of nanowire light sensor arrays mimicking the photoreceptors in the correlating natural version. The nanowire arrays are connected to a bundle of liquid-metal wires serving as nerves behind the artificial retina for the purpose of tests during the experiment.
Data findings demonstrate the nanowires enjoy a higher density than photoreceptors in the human eye meaning the artificial retina can receive more light signals. This means the nanowires can potentially attain a higher image resolution than the biological version. Results show the hemispherical retina is workable as it is capable of replicating visual signals produced by the prosthetic eye onto a computer screen.
A new potential option for eye-loss
The lab explains their biomimetic eye involves an electrochemical process adopted from a type of solar cell, whereby, each photosensor on the artificial retina could possibly serve as a nanoscale solar cell to self-power the prostheses.
They go on to add the potential may also exist to use different materials to boost the sensors’ sensitivity and spectral range to achieve other functions such as night vision.
They conclude these nanowire arrays could be directly connected to the nerves of visually impaired patients. This in turn would eliminate the blind spot found in the human line-of-vision caused by the natural bundle of optic nerve fibers routing through a pore at the back of the eye.
The team surmises they have developed a solar-powered 3D artificial eye outperforming current bionic eyes and their biological variants in certain circumstances. For the future, the researchers state they now plan to improve the performance, stability, and biocompatibility of their device.
Source: Hong Kong University of Science and Technology (HKUST)
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