A number of research groups are working on developing electronic ink but so far, the screens cannot switch from one image to the next quickly enough to display video. Robert A. Hayes and B.J. Feenstra of Philips Research Eindhoven in the Netherlands overcame this hurdle by manufacturing an electronic-paper prototype based on a process known as electrowetting. In the new design, each pixel is a tiny chamber that has a water-repelling base over a white background. These containers are filled with colored oil and topped off with water. Left alone, the oil forms a flat film between the bottom and the water. But when a voltage is applied to the base, the oil film contracts and moves aside, allowing light to reflect off of the white background and changing the appearance of the pixel. Full color displays can then be achieved by combining subcells of yellow, cyan and magenta.
Because the voltage required for the transformation is quite low, the scientists envision portable electronic paper that won't require a prohibitively large power source. In addition, the pixel changes occur in less than ten milliseconds--a speed compatible with showing videos--and the picture is four times brighter than conventional reflective liquid-crystal displays.
