New Artificial Retina Made From Solar Cells Can Recognize Handwritten Numbers

Perovskites are a group of materials with a particular crystal structure, and are very adept at absorbing light. The Solar Energy Technologies Office describes them as an ideal material for producing solar cells with, as they have the potential “for high performance and low production costs.”

But it’s not just solar cells that require light-absorbing properties. Our own retinas do so too, and creating artificial retinas with a similar material could lead to some promising results in the realm of sight restoration. 

This is the focus of a paper published by KAUST researchers in the journal Light: Science & Applications. The study details the construction of a device that acts as an electronic retina, supposedly enabling it to “see” the same way a human eye would. 

“Existing systems use photodetectors that require power for their operation and thus consume a lot of energy, even on standby,” explains Khaled Nabil Salama, one of the researchers. “In contrast, our proposed photoreceptors… don’t consume static power for their operation.”

Perovskite nanocrystals were embedded onto a polymer, which was then sandwiched between two electrodes. On the bottom is aluminum, and on the top, indium tin oxide. The latter lets light pass through, hitting the perovskite layer, thanks to it being etched. This setup evokes photoreceptors.

Then all of this was attached to a CMOS sensor and neural network with 100 output neurons, and this resided on a thin layer of polyimide so it would be flexible enough to replicate the human eye. 

When LEDs of different colors were used to light up the device, the team found that the response was similar to that of the human eye. It was sensitive to green light in particular. 

In another test, the device showed extremely promising results: it was able to recognize handwritten numbers with around 72% accuracy, as detailed by New Atlas.

Even after 129 weeks of storage, the photoreceptors didn’t change much in their results, indicating that they’re highly stable.

Despite this, though, the researchers have stated that the photoreceptor array would actually be more suitable in things like cameras and robots, instead of becoming something that can be transplanted into humans with visual disabilities. 

“The ultimate goal of our research in this area is to develop efficient neuromorphic vision sensors to build efficient cameras for computer vision applications,” Salama clarifies. 

[via New Atlas and Tech Xplore, image by Xavier Pita for KAUST]