https://engineer.fabcross.jp/archeive/200608_electrochemical-eye.html
2020-6-17Technical News, International News, Electrical and Electronics EC-EYE (ElectroChemical Eye), Nature, perovskite nanowire array, artificial eyeball, artificial retina, medical robot, academic, aluminum oxide membrane, Hong Kong University of Science and Technology
A research team at the Hong Kong University of Science and Technology has developed a spherical visual system that mimics the human eyeball. High resolution is achieved by densely integrating perovskite nanowire arrays into an artificial retina, which is expected to have applications in robotics and artificial eyes. The research results were published in Nature on May 20, 2020.
Because the human eye has extraordinary image sensing capabilities, such as a wide field of view and high resolution, there is a great need for devices that mimic it. However, it is very difficult to reproduce the spherical shape of the human retina, and “the artificial vision currently used in hospitals can only mimic a part of the retina because it uses a flat IC chip, so the vision is not clear,” noted Professor Zhiyong Fan, who led the research team. In 2012, I came up with the idea of using nanowires and external electronic circuits to integrate a high-density sensor into a spherical surface,” he said, explaining the starting point of the research.
The team fabricated an artificial retina by embedding nanowires made of perovskite material densely embedded in an aluminum oxide film fabricated into a hemisphere. Perovskite is a material also used in solar cells, where it functions as an optical sensor that converts light energy into electricity. The number of sensors in the prototype is 30 times that of the human eye, and the distance between the sensing rods was kept to 3 μm. Signals from the sensors are transmitted to an external circuit via liquid metal wires.
It was further combined with an aluminum hemispherical shell to form a spherical shape, filled with ionic liquid to allow charged particles to travel inside, and a lens was placed in front of the device. In other words, the lens is the lens, the ionic liquid is the vitreous body, the nanowires are the photoreceptor cells, and the liquid metal is the optic nerve.
Tests of the artificial eyeball, dubbed “EC-EYE (ElectroChemical Eye),” showed that each nanowire captured 86 photons per second under the darkest conditions. The device's responsiveness and recovery were equal to or better than that of the human eye. The letters “E,” “I,” and “Y” could also be projected onto the artificial eyeball and reproduced. The resolution is still only 10 x 10 pixels, but higher resolution can be achieved by processing each sensor individually.
According to the research team, the robot can be used in medical robots that care for patients, and they also hope that it can be used for the visually impaired by combining appropriate biocompatible materials.
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PROF. ZHIYONG FAN LED HIS TEAM TO CRAFT A “SUPER HUMAN EYE” THAT WORKS LIKE THE REAL ONE
A biomimetic eye with a hemispherical perovskite nanowire array retina
Translated with DeepL.com (free version)
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