Electronic paper

Jing Wei

These images were created on the paper of the future

Digital media may be prevalent in today’s society, but sometimes an electronic screen just won’t do. The average office employee still prints thousands of pages of paper each year, and large posters and banners remain the norm at conferences and trade shows. In an effort to reduce the environmental impact of making and shipping reams of paper, researchers have developed a rewritable paperlike surface that can be printed and erased 40 times without a loss in resolution. The flexible membrane is made of tungsten oxide—used in “smart windows” that modulate the amount of sunlight and heat passing through—and a water-soluble polymer. The surface is “printed” by selectively exposing it to ultraviolet (UV) light, which causes the colorless tungsten oxide to turn blue. The color change takes just a matter of seconds, far more rapid than previous experiments with rewritable surfaces. The printed pattern (example pictured) naturally fades over time in the presence of oxygen but remains visible for several days in normal atmospheric conditions. The membranes can also be bleached colorless in less than about half an hour by exposing them to either ozone or heat, the team reports in Applied Materials & Interfaces. Commercializing this technology would be relatively straightforward, the researchers propose. The raw materials necessary to make the membranes are all industrially available, and UV lamps are commonly used to sterilize food and equipment. An immediate application, the scientists suggest, is to incorporate these membranes into fabric to create the ultimate in customizable clothing: a new logo or advertisement every time you go out.