Portland, Ore. -- Swiss researchers have found a way to directly make any color that can be perceived by the human eye on a computer screen. Instead of mixing red, green and blue, as is done today, electrical engineers at the Swiss Federal Institute of Technology (Zurich) have crafted an electrically controlled, flexible diffraction grating that can be tuned in real-time to any possible color. Though they have so far made only a single pixel, the EEs say that displays based on their technology could one day emit a unique color at each pixel by sending the appropriate electrical voltage to its deformable diffraction grating.
Creating a spectrum of colors on a computer display is now accomplished by mixing RGB subpixels. But mixing three primary colors can represent only a fraction of the color space that the human eye can perceive.
Now, the Swiss team believes it has found a way around the problem. Its electrically deformable diffraction grating is fabricated by sandwiching an electroactive-polymer dielectric--also called an artificial muscle--between two flexible conductors. The diffraction grating separates white light into a spectrum of colors in the same way that prisms do. When a voltage is applied, the conductors are attracted to each other, thereby squeezing the sandwiched polymer, which causes it to spread out.
Diffraction grating bends
By attaching a flexible diffraction grating atop the structure, it will deform too, thus changing the angles of the color spectrum it emits. A hole is then fabricated atop the diffraction grating so that only a single color is emitted from that pixel location. By sending different voltages to each pixel's deformable diffraction grating, any possible color can be emitted through the hole. The group's polymer was demonstrated to cover the entire visible spectrum.
Next, the team will try to reduce the volts needed to deform the diffraction grating to the low voltages used on chips today.