Gyricon Electronic paper was first developed in the 1970s by Nick Sheridon at
Xerox's
Palo Alto Research Center. The first electronic paper, called
Gyricon, consisted of polyethylene spheres between 75 and 106 micrometers across. Each sphere is a
Janus particle composed of negatively charged black plastic on one side and positively charged white plastic on the other (each bead is thus a
dipole). The spheres are embedded in a transparent silicone sheet, with each sphere suspended in a bubble of oil so that it can rotate freely. The polarity of the voltage applied to each pair of electrodes then determines whether the white or black side is face-up, thus giving the pixel a white or black appearance. A benefit of this type of e-paper is that the contents are retained even after the voltage have been stopped. At the FPD 2008 exhibition, Japanese company Soken demonstrated a wall with electronic wall-paper using this technology. In 2007, the Estonian company Visitret Displays was developing this kind of display using
polyvinylidene fluoride (PVDF) as the material for the spheres, dramatically improving the video speed and decreasing the control voltage needed.
Electrophoretic An
electrophoretic display (
EPD) forms images by rearranging charged pigment particles with an applied
electric field. In the simplest implementation of an EPD,
titanium dioxide (titania) particles approximately one micrometer in diameter are dispersed in a
hydrocarbon oil. A dark-colored dye is also added to the oil, along with
surfactants and charging agents that cause the particles to take on an electric charge. This mixture is placed between two parallel, conductive plates separated by a gap of 10 to 100
micrometres. When a voltage is applied across the two plates, the particles migrate
electrophoretically to the plate that bears the opposite charge from that on the particles. When the particles are located at the front (viewing) side of the display, it appears white, because the light is scattered back to the viewer by the high-index titania particles. When the particles are located at the rear side of the display, it appears dark, because the light is absorbed by the colored dye. If the rear electrode is divided into a number of small picture elements (
pixels), then an image can be formed by applying the appropriate voltage to each region of the display to create a pattern of reflecting and absorbing regions. EPDs are typically addressed using
MOSFET-based
thin-film transistor (TFT) technology. TFTs are often used to form a high-density image in an EPD. A common application for TFT-based EPDs are e-readers. Electrophoretic displays are considered prime examples of the electronic paper category, because of their paper-like appearance and low power consumption. Examples of commercial electrophoretic displays include the high-resolution
active matrix displays used in the
Amazon Kindle,
Barnes & Noble Nook,
Sony Reader,
Kobo eReader, and
iRex iLiad e-readers. These displays are constructed from an electrophoretic imaging film manufactured by
E Ink Corporation. A mobile phone that used the technology is the
Motorola Fone. Electrophoretic Display technology has also been developed by SiPix and
Bridgestone/Delta. SiPix is now part of E Ink Corporation. The SiPix design uses a flexible 0.15 mm Microcup architecture, instead of E Ink's 0.04 mm diameter microcapsules.
Bridgestone Corp.'s Advanced Materials Division cooperated with Delta Optoelectronics Inc. in developing Quick Response Liquid Powder Display technology. Electrophoretic displays can be manufactured using the
Electronics on Plastic by Laser Release (EPLaR) process, developed by
Philips Research, to enable existing
AM-LCD manufacturing plants to create flexible plastic displays.
Microencapsulated electrophoretic display ] In the 1990s another type of electronic ink based on a microencapsulated electrophoretic display was conceived and prototyped by a team of undergraduates at MIT as described in their Nature paper. This used tiny microcapsules filled with electrically charged white
particles suspended in a colored
oil. In early versions, the underlying
circuitry controlled whether the white particles were at the top of the capsule (so it looked white to the viewer) or at the bottom of the capsule (so the viewer saw the color of the oil). This was essentially a reintroduction of the well-known
electrophoretic display technology, but microcapsules meant the display could be made on flexible plastic sheets instead of glass. One early version of the electronic paper consists of a sheet of very small transparent capsules, each about 40
micrometers across. Each capsule contains an oily solution containing black dye (the electronic ink), with numerous white
titanium dioxide particles suspended within. The particles are slightly negatively
charged, and each one is naturally white. These are commercially referred to as Active Matrix Electrophoretic Displays (AMEPD).
Reflective LCD This technology is similar to common
LCD while the
backlight panel is substituted by a reflective surface. A comparable technology is also obtainable in backlight LCDs by software or hardware deactivating the backlight control.
Electrowetting Electrowetting display (
EWD) is based on controlling the shape of a confined water/oil interface by an applied voltage. With no voltage applied, the (colored) oil forms a flat film between the water and a hydrophobic (water-repellent) insulating coating of an
electrode, resulting in a colored pixel. When a voltage is applied between the electrode and the water, the interfacial tension between the water and the coating changes. As a result, the stacked state is no longer stable, causing the water to move the oil aside. This makes a partly transparent pixel, or, if a reflective white surface is under the switchable element, a white pixel. Because of the small pixel size, the user only experiences the average reflection, which provides a high-brightness, high-contrast switchable element. Displays based on
electrowetting provide several attractive features. The switching between white and colored reflection is fast enough to display video content. It is a low-power, low-voltage technology, and displays based on the effect can be made flat and thin. The reflectivity and contrast are better than or equal to other reflective display types and approach the visual qualities of paper. In addition, the technology offers a unique path toward high-brightness full-color displays, leading to displays that are four times brighter than reflective LCDs and twice as bright as other emerging technologies. Instead of using red, green, and blue (RGB) filters or alternating segments of the three primary colors, which effectively result in only one-third of the display reflecting light in the desired color, electrowetting allows for a system in which one sub-pixel can switch two different colors independently. This results in the availability of two-thirds of the display area to reflect light in any desired color. This is achieved by building up a pixel with a stack of two independently controllable colored oil films plus a color filter. The colors are
cyan, magenta, and yellow, which is a subtractive system, comparable to the principle used in inkjet printing. Compared to LCD, brightness is gained because no polarisers are required.
Electrofluidic Electrofluidic display is a variation of an electrowetting display that place an aqueous pigment dispersion inside a tiny reservoir. The reservoir comprises less than 5-10% of the viewable pixel area and therefore the pigment is substantially hidden from view. Voltage is used to electromechanically pull the pigment out of the reservoir and spread it as a film directly behind the viewing substrate. As a result, the display takes on color and brightness similar to that of conventional pigments printed on paper. When voltage is removed liquid surface tension causes the pigment dispersion to rapidly recoil into the reservoir. The technology can potentially provide greater than 85% white state reflectance for electronic paper. The core technology was invented at the Novel Devices Laboratory at the
University of Cincinnati and there are working prototypes developed by collaboration with
Sun Chemical,
Polymer Vision and Gamma Dynamics. It has a wide margin in critical aspects such as
brightness,
color saturation and
response time. Because the optically active layer can be less than 15 micrometres thick, there is strong potential for
rollable displays.
Interferometric modulator (Mirasol) The technology used in
electronic visual displays that can create various colors via
interference of reflected light. The color is selected with an electrically switched light
modulator comprising a
microscopic cavity that is switched on and off using
driver integrated circuits similar to those used to address
liquid-crystal displays (LCD).
Plasmonic electronic display Plasmonic nanostructures with conductive polymers have also been suggested as one kind of electronic paper. The material has two parts. The first part is a highly reflective metasurface made by metal-insulator-metal films tens of nanometers in thickness including nanoscale holes. The metasurfaces can reflect different colors depending on the thickness of the insulator. The standard RGB color schema can be used as pixels for full-color displays. The second part is a polymer with optical absorption controllable by an electrochemical potential. After growing the polymer on the plasmonic metasurfaces, the reflection of the metasurfaces can be modulated by the applied voltage. This technology presents broad range colors, high polarization-independent reflection (>50 %), strong contrast (>30 %), the fast response time (hundreds of ms), and long-term stability. In addition, it has ultralow power consumption (10000 dpi). Since the ultrathin metasurfaces are flexible and the polymer is soft, the whole system can be bent. Desired future improvements for this technology include bistability, cheaper materials and implementation with TFT arrays.
Retina E-paper In 2025, researchers at Uppsala University introduced a "retina electronic paper" — a reflective display technology that reaches the resolution limit of the human eye. Unlike emissive displays such as LEDs or OLEDs, which lose brightness and contrast as pixel sizes shrink, retina E-paper employs electrically tunable nanostructures made of
WO₃ that reflect ambient light efficiently. Each color "metapixel," composed of nanoscale WO₃ disks, can be dynamically modulated through an electrochemical insulator-to-metal transition, enabling color tuning and video-rate operation (>25 Hz). The resulting display achieves pixel densities above '25,000 pixels per inch', with high reflectance (~80%) and optical contrast (~50%), while consuming very low power. The approach combines the visual comfort of paper-like viewing with the precision of nanophotonic control, and has been described as a potential platform for future ultra-high-resolution, energy-efficient VR/AR systems enabling fully immersive visual experiences.
Other technologies Other research efforts into e-paper have involved using
organic transistors embedded into
flexible substrates, including attempts to build them into conventional paper. Simple color e-paper consists of a thin colored optical filter added to the monochrome technology described above. The array of pixels is divided into
triads, typically consisting of the standard cyan, magenta and yellow, in the same way as
CRT monitors (although using subtractive primary colors as opposed to additive primary colors). The display is then controlled like any other electronic color display. ==History==