Super bionic eyes come out, some performance surpasses human eyes, and complete replacement is still far away
After testing, the photosensitivity effect of the artificial retina is almost equivalent to that of the human retina. At the same time, its photoreceptor cells have a much shorter response and recovery time than the retina of the human eye.
Such scenes often appear in science fiction movies: intelligent robots with bionic eyes can achieve long-range precision strikes on targets; blind people with visual impairments can fully restore their eyesight by implanting bionic eyes... don’t think that this is just a screenwriter. Imagination, in fact, scientists have been committed to creating an ideal bionic visual installation as in the movie, and have made some progress.
High-performance bionic eyes must be based on excellent artificial retinas. Recently, scientists from Hong Kong, China and the US scientific research team have developed a high-density hemispheric artificial retina. The researchers said that the EC-EYE bionic eye assembled by the artificial retina successfully imitated the human eye for the first time in appearance, and some indicators can theoretically be comparable to the human eye. Not long ago, the result was published in the form of a paper in the international academic journal Nature.
The retina is the key to the human eye seeing the world
The eye is an important sensory organ for most living things on the earth, especially for human beings. It is understood that about 80% of the environmental information obtained by humans comes from the eyes.
Light enters the eyeball from the outside, passes through the cornea, lens, and vitreous, and then focuses on the retina. The retina converts the obtained information into a bioelectrical signal, which is transmitted to the cerebral cortex through the optic nerve. The brain automatically analyzes the signal to generate an image. This is the entire visual formation. process.
The wide field of view, high resolution and high sensitivity of the human eye greatly benefit from the retina. It is understood that although the retina area of the human eye is less than 5 square centimeters, there are 137 million photoreceptor cells on it, of which 130 million are rod-shaped rod cells to sense low light and black and white images; 7 million The cone-shaped cone cells are used to sense strong light and color vision.
Huang Yan, deputy director of the Department of Ophthalmology and Optics, School of Medical Technology and Engineering, Fujian Medical University, pointed out that from a medical point of view, if the human eyeball is compared to a camera, the cornea is the lens, and the retina is like a film. The image signal on the retina is transmitted to the brain, which can form the visual impression in the human mind.
However, the human eyeball is different from the camera, and the image in the human eye and the external environment are not as simple as the mirror relationship. The left and right eyes of a normal person are regulated by the brain and can maintain a certain positional relationship. It can obtain different image fragments from all directions and multiple angles, and then generate a unified surround stereo image through brain fusion; in a dynamic environment, even in a fast running state, The human eye can still obtain a stable image; in addition, the human eye also has the ability to adapt to light, regardless of the light intensity, it can automatically adapt to the brightness.
Concave hemisphere shape solves the problem of bionic eye image focusing
The current main cause of blindness in most patients is retinal degenerative disease. Once the retina is damaged, the human eye cannot receive light information and cannot produce visual signals. One of the keys to whether the bionic eye can help people "see the world" is whether it can simulate the precise human retina structure.
The retinal structure of the human eye is very complex, especially the concave hemispheric shape of the retina, which has always been a major problem in the development of bionic eyes.
The lens of the human eye is curved, and the light will bend after passing through the lens. The image formed in this way is usually curved. The retina of the human eye can perfectly capture the curved image, but the conventional visual device uses a planar sensor to capture the curved image , The image cannot be fully focused, and some areas will be blurred.
The hemispherical artificial retina invented by Chinese and American researchers has successfully solved the problem that the image cannot be focused by making it into a concave hemispherical shape.
In the manufacturing process, they used a perovskite photosensitive nanowire to act as a "photoreceptor cell", which was closely arranged on a hemispherical substrate to simulate the composition of the human eye's retina.
After testing, the photosensitivity effect of the artificial retina is almost equivalent to that of the human retina. At the same time, it can also respond within 19.2 milliseconds after receiving light stimulation, and return to its original state within 23.9 milliseconds, which is much shorter than the response and recovery time of the photoreceptor cells in the human eye retina in 40-150 milliseconds.
There is still a long way to go to fully replace the human eye
Can this kind of bionic eye perfectly replace the human eye? the answer is negative.
Huang Yan pointed out that about 1 million light-emitting points can be felt by the photoreceptor cells of the normal human eye, and these light-emitting points can form a clear image. Although the artificial retina can achieve the corresponding performance index, its stability is still difficult to guarantee.
Although the sensational bionic eye's ability to acquire images has been greatly improved, the electronic signal transmitted by the bionic eye is not completely consistent with the biological signal of the human eye. The two cannot be fully converted, and have a central nervous system stimulation effect. Different. The current research has not completely solved the working mechanism of the brain to process biological signals, so it is still unknown when the artificial retina can completely replace the human eye retina.
In addition, because the performance of the electrochemical device will decline over time, the artificial retina also needs more tests to improve in order to extend the service life.
Although it cannot completely replace the human eye, "without considering volume and power consumption, some of the performance of the bionic eye can far exceed the human eye, such as extreme visual distance, microscopic vision capabilities, infrared observation capabilities," Chinese Academy of Sciences Zhang Xiaolin, director of the Bionic Vision Laboratory at the Shanghai Institute of Microsystems and Information Technology, said that although the artificial retina cannot fully restore vision to blind patients, it can at least allow them to recognize objects with blurred shapes, etc., to a certain extent, which is convenient for patients' daily lives.
At the same time, Zhang Xiaolin pointed out that although the application of bionic eyes in the medical field has yet to be vigorously promoted, in the development of intelligent robots, the combination of bionic eyes and artificial intelligence chips has been successfully applied. For example, a robot on an industrial assembly line can accurately grab items on a fast-moving conveyor belt. In addition, the Bionic Eye is also expected to be used in fields such as unmanned driving, drone navigation, and automatic tracking of sports events, so that future robots will be more intelligent.
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Artificial visual devices are not suitable for all blind people
Scientists have developed a visual device that simulates the function of the human eye. The cornea, lens, and vitreous are not required. Instead, the camera is used to obtain image information, and then the image is transmitted by the wireless transmitter to the artificial retina on the surface of the eyeball, and converted into The electrical pulse signal stimulates the optic nerve through the electrode to send a signal to the brain.
For example, in 2010, a company called "Second Vision" implanted an artificial vision device called "Argus II" into the right eye of 68-year-old retired British engineer Eric Selby. Previously, the patient had been blind for nearly 20 years due to severe damage to the retina. After the operation, the patient could vaguely "identify" some sidewalk scenes and other scenes.
But it is worth noting that blind people with congenital visual impairment and long-term blindness that cause visual atrophy are not suitable for installing such devices.
In addition, the effect achieved by this technology is only to allow patients to have a simple sense of light, seeing a black and white world similar to a "mosaic", lacking vivid natural colors, and unable to achieve the image quality captured by normal human eyes. "After a certain amount of training, patients can distinguish some simple objects from the background. For example, if they see 3 points and can move at the same time, it may mean that the thing in front of them is a triangle." Huang Yan said.
Our reporter Xie Kaifei correspondent Zhang Qiao