In the race to develop mass-market, color e-ink displays, researchers from the University of Cincinnati have developed a new technology that uses ambient light and pigments used in commercial printing that can make thin electronic displays with vibrant, glossay images, according to IEEE Spectrum writer Rosaleen Ortiz, who quoted research reported in Nature Photonics.
Over the past two years, Ortiz reported in “Ohio Engineers Ink New Electronic Paper Technology,” University of Cincinnati’s Novel Devices Laboratory has developed electrofluidic display (EFD) technology in collaboration with Sun Chemical, an ink and pigments manufacturer. Sun Chemical also funded the work and has applied for a patent on the technology with the university. To expedite commercialization, the partnership spun off a new company, Gamma Dynamics, with John Rudolph as president (formerly with Corning) and U.C. Professor Jason K. Heikenfield as principal scientist.
An EFD display comprises two sheets of plastic. Polymer structures are printed on one sheet to form pixels. For each pixel, a tiny hole (roughly 50 micrometers) is formed in the polymer and filled with a droplet of pigmented fluid. A trench cut into the polymer that contains air or oil surrounds the pixel. Topping the pixels, another plastic sheet contains a transparent electrode, leaving a 3-µm gap between it and the polymer pixel.
When there’s no charge between the plastic sheets, the pigment stays inside the hole, essentially invisible. But when voltage is applied, the pigment is pulled out of the hole and spread out along the glass, revealing its color to the viewer. The air or oil that surrounds the pixel prevents the pigment in one pixel from spilling into another. Switching off the power lets the pigment recoil back into the hole.
Heikenfeld, who led the research and is director of the Novel Devices Laboratory, said electronic paper would be only one of many possible applications. There is also potential for rollable displays, adaptive camouflage and even color-changing cellphone cases.
Prototypes may roll out in about three years, he said, followed by the commercialization of some of the simpler applications.