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6 hours ago
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As the transfer of information in our society becomes more complex, so the demand increases for screens that transmit images and video with precision.
‘The technology that we have developed can provide new ways to interact with information and the world around us. It could expand creative possibilities, improve remote collaboration, and even accelerate scientific research,’ says Kunli Xiong, Associate Senior Lecturer/Assistant Professor at the Department of Materials Science and Engineering at Uppsala University, who conceived the project and is the lead author of the study.
Electronic paper
It is the size and number of pixels that determine the resolution, and thereby how realistic images and films displayed on screens can be. In virtual or augmented reality, where the screen is small and close to the eye, the experience is limited by the fact that today’s pixels cannot be made small enough. On a micro-LED screen, for example, pixels work poorly when they become smaller than one micrometre in size. However, in the article Video‐rate tunable colour electronic paper with human resolution published in the scientific journal Nature, researchers present retina E-paper, a new type of electronic paper, or reflective screen. Each pixel is approximately 560 nanometres and the overall screen area is comparable to the size of the human pupil, with a resolution of beyond 25,000 ppi (pixles per inch).
Illustration of a pupil-sized display inspired by the human retina, packed with ultrahigh-resolution submicrometre pixels.
Photo: Nature
Millimetre-art
‘This means that each pixel roughly corresponds to a single photoreceptor in the eye, i.e. the nerve cells in the retina that convert light into biological signals. Humans cannot perceive a higher resolution than this,’ says Andreas Dahlin, Professor at the Department of Chemistry and Chemical Engineering at Chalmers.
The retina E-paper can be placed very close to the eye. To demonstrate the technology's performance, researchers recreated an image of Gustav Klimt’s famous artwork ‘The Kiss’ on a surface area of approximately 1.4 × 1.9 millimetres. By way of comparison, this means that the image was 1/4000th that of a standard smartphone.
Tungsten oxide
As in previous research led by Andreas Dahlin, the screen is passive, meaning that it does not contain its own light source; instead, the colours of the pixels appear when ambient light hits small structures on a surface. The same principle can be found in the magnificent plumage of small birds. The ultrasmall pixels contain particles of tungsten oxide. By adjusting the size of the particles and how they are positioned in relation to one another, the researchers have succeeded in controlling how the colours in light are diffused and reflected, thereby creating pixels in the colours red, green and blue, which can then be used to generate all colours. By applying a weak voltage, the particles can be ‘switched off’ and they will turn black.
‘This is a major step forward in the development of screens that can be shrunk to miniature size while improving quality and reducing energy consumption. The technology needs to be fine-tuned further, but we believe that retina E-paper will play a major role in its field and will eventually have impact on us all,’ says Giovanni Volpe, Professor at the Department of Physics at the University of Gothenburg.
Scientific article in Nature: Video‐rate tunable colour electronic paper with human resolution
Contact information: Giovanni Volpe, Professor at the Department of Physics at the University of Gothenburg, Sweden +46 (0)766-22 91 37, [email protected]
