US, WASHINGTON (ORDO NEWS) — Scientists have created a device that simulates the work of the human eye. In a number of parameters, it surpasses its natural counterpart.
The achievement is described in a scientific article published in the journal Nature by a group led by Zhiyong Fan from the Hong Kong University of Science and Technology.
Artificial eyes, performing the functions of a natural organ, could restore sight to blind and visually impaired people. Robots such a miracle of technology would also be useful. And, it seems, experts from China and the USA are already close to giving such a device to both a person and a car.
The artificial eyeball is similar in shape to the human eye and has all its main components. It has a crystalline lens, an iris, a vitreous body, a light-sensitive retina and “nerve fibers” through which the signal is transmitted “to the brain”.
After passing through the lens (lens), the light is additionally focused by the vitreous body, the role of which is played by the ionic liquid . From here, he lands on an artificial retina.
It has the same hemispherical shape as the human retina. This reduces the area of the light spot and helps to better focus the image.
The role of photosensitive cells is played by nanowires of lead formamidine iodide (FAPbI 3). This material belongs to the class of perovskites. The latter are famous for their ability to generate electricity in response to incident light, and therefore are often used in experimental solar panels.
Photocells are located in the pores of an aluminum oxide membrane lining the inner surface of the artificial eye. From them go wires (“nerve fibers”). These are soft elastic tubes filled with a liquid alloy of gallium and indium.
The sensitivity of the artificial retina is not inferior to the natural one: at the lowest measured intensity, each photocell detected an average of 86 photons per second.
The width of the field of view of an artificial eye is also almost human: 100 degrees (for a motionless human eye, it is 130 degrees vertically, but we see only a negligible fraction of this field in color and details).
The used perovskite photoreceptors are almost equally sensitive to photons of different wavelengths. That is, the world seen with such an electronic eye would be black and white.
But in some ways, the new device exceeds the capabilities of human vision. For example, it creates a much more detailed image.
Let’s explain. To distinguish between subtle details, you need to know as precisely as possible which points of the retina the light has hit and which are not. This accuracy depends on two things: the number of photoreceptors per square centimeter and the ability of the system to process the signal of each receptor (or at least small groups of receptors) individually.
The electronic eye is superior to the human in both respects. Firstly, he has 46 times more photoreceptors per square centimeter.
Secondly, the photocells in the new system are combined in pixels of two or three pieces, and a separate wire fits each pixel. In the human optic nerve, there are 120 times fewer individual fibers than there are photosensitive cells on the retina. Therefore, the slogan “each receptor has a separate communication line” is more or less close to life only in the central fossa of the retina with a diameter of 0.2-0.4 millimeters. Only in this tiny area do we distinguish the subtle details of the image. The rest of the retina remains to perceive the world in the form of dim spots of light and shadow.
Electronics once again overtook the human body in speed. The device has enough exposure for 19 milliseconds to generate a signal. And when the flash goes out, the photocell is ready for use again after 24 milliseconds. Our retina, however, requires 40-150 milliseconds for both.
In short, the artificial eye looks very promising. But scientists still have work to do.
First of all, only a hundred pixels are present on the electronic retina. For a full vision, this amount should be increased.
In addition, the resulting device is expensive, and to make such a design is difficult. To make such artificial eyes a mass product, the technology will have to be cheapened.
A separate problem may be the integration of this “organ of vision” with the human nervous system.
Finally, the service life of the new items is also unclear. Long trials are needed to make sure that the system does not degrade soon after it is introduced into the body.
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