What e-ink is and how it works: present and future of electronic ink

The technology ofelectrostatic ink dates back to the mid-90s and was created to imitate the paper, sacrificing – compared to other types of displays – fluidity and color management in favor of readability, with very low consumption. It is no coincidence that it is commonly used for e-books. As much as it may appear to be an “outdated” technology, it continues to resist the advance of modern technologies OLED. Let’s find out what the e-link is, how it works and how it is used.

What is e-ink, how it works and why it was born

If we want to understand how we arrived at modern times e-books and their screens, we must take a big step back, looking at the first patents on electronic paper by Xerox in the 1970s with the Gyricon project.

This technology was based on two-color spheres (white/black) microscopic, between 70 and 120 nm, equipped with a charge dipole, that is, one face with a positive charge and a negative one. The spheres, immersed in oil-filled cavities between two plastic membranes, if subjected to an electromagnetic field they could be oriented in order to reproduce images or texts.


The generated drawings could remain imprinted on the screen until further modifications, maintaining the imposed orientation even with the screen turned offand thanks to the materials used the product was flexible and foldable. The screen, not backlitcould only be used in the light, with the advantage however of in a less strain on the eye compared to traditional monitors.

The current state of electronic paper: color on e-paper

In the following decades, progress was impressive: with the introduction of electrophoretic ink (composed of hundreds of tiny charged particles dispersed in dielectric liquids) and the progressive miniaturization of electronicsit is possible to have today several electrodes per pixelallowing the use of nuances compared to the initial black/white limitation.


As for the lighting, i Modern e-readers are often illuminated to allow reading in dark environments: theintensity some reflected light still remains much less compared to common backlit screens, thanks to the natural contrast between the pigments.

The most recent developments have also focused on finally bringing color to electronic paper, using RGB filters (red, yellow and blue) under the transparent film to “color” the light reflected by the white pigments, or particles of different colors for each pixel. This last technology is the one chosen, for example, for electronic labels which indicate the prices of goods in many supermarkets.

The most “exotic” uses of e-ink

If in the first decades electronic inks remained relegated to the screens of readers or small electronic instruments, today we can find this technology in very distant areas.

A reality that has been established for years is that of electrically tinted windows smart glassespanels that are increasingly widespread in offices and homes for reasons that can range from search for privacy todarkening of solar radiation in the summer months to reduce the internal temperature. With a simple click, it is possible to switch from transparent to opaque glass, often if possible keep the configuration choice even without electricity consumption.


A possible future application is that shown by BMW, which in 2022 showed a prototype with wrap film capable of change color on request. The company highlights how, in addition to aesthetic value and “personal” color of the car, the possibility of switch from light to dark colors can increase the efficiency of the vehicle reducing the absorption of energy and heat on summer days and allowing, especially in the case of electric vehicles, a greater autonomy due to lower consumption by air conditioning systems.