Maximizing Resolution: The Power of Minimal Pixels

The transfer of information in our society is becoming increasingly intricate, leading to a higher demand for screens that can transmit images and videos with utmost precision. A group of researchers from Chalmers University of Technology, the University of Gothenburg, and Uppsala University in Sweden have introduced a screen technology featuring the tiniest pixels ever created, achieving the highest resolution discernible by the human eye.

The pixels utilize nanoparticles to reproduce colors, with their size and arrangement controlling how light is scattered. The optical properties of these nanoparticles can be electrically adjusted. This groundbreaking achievement, detailed in a paper published in Nature, sets the stage for creating virtual worlds that are virtually indistinguishable from reality.

“The technology we’ve developed opens up new avenues for interacting with information and our surroundings. It has the potential to enhance creative opportunities, improve remote collaboration, and even accelerate scientific research,” explains Kunli Xiong, Associate Senior Lecturer/Assistant Professor at the Department of Materials Science and Engineering at Uppsala University, the brain behind the project and the lead author of the study.

The resolution of screens, and thus the realism of images and videos displayed on them, is determined by the size and number of pixels. In virtual or augmented reality settings, where the screen is small and close to the eye, the experience is currently limited by the inability to make pixels small enough. For instance, on a micro-LED screen, pixels start performing poorly when they shrink below 1 micrometer in size.

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To address this challenge, the researchers introduce retina E-paper, a novel form of electronic paper or reflective screen. Each pixel measures approximately 560 nanometers, and the total screen area is comparable to the size of the human pupil, boasting a resolution exceeding 25,000 pixels per inch (ppi).

“This implies that each pixel essentially corresponds to a single photoreceptor in the eye, which are the nerve cells in the retina responsible for converting light into biological signals. Humans cannot discern a resolution higher than this,” notes 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 showcase the technology’s capabilities, the researchers recreated an image of Gustav Klimt’s renowned artwork “The Kiss” on a surface area of approximately 1.4 × 1.9 millimeters. For comparison, this means the image was 1/4000th the size of a standard smartphone display.

Similar to previous research led by Dahlin, the screen is passive, meaning it doesn’t have its own light source; instead, the colors of the pixels emerge when ambient light interacts with small structures on the surface. This principle is akin to the dazzling plumage of small birds.

The ultrasmall pixels contain tungsten oxide particles. By manipulating the size and positioning of these particles relative to each other, the researchers have successfully controlled how colors in light are diffused and reflected, resulting in pixels in red, green, and blue, which can be combined to produce all colors. Applying a weak voltage can “turn off” the particles, causing them to appear black.

“This marks a significant advancement in the development of screens that can be miniaturized while enhancing quality and reducing energy consumption. Further refinements are necessary, but we believe that retina E-paper will have a profound impact in its field and eventually influence us all,” states Giovanni Volpe, Professor at the Department of Physics at the University of Gothenburg.