Even in an increasingly digital world, there's still a need for printed text. But wasting paper could be a thing of the past with new technology under development by a research team from the Lawrence Berkeley National Laboratory; the University of California, Riverside; and China's Shandong University. This new paper is printed with light instead of ink, allowing it to be reused up to dozens of times, Co.Design reports.
The paper, described in Nano Letters, is blue rather than white, and it's covered in a nanoparticle coating that is sensitive to UV light. These titanium dioxide nanoparticles are mixed with Prussian blue pigment (the blue color in blueprints), which becomes colorless when its particles gain electrons. The reaction that occurs when these pigments are exposed to UV light turns the blue clear. After about five days—or 10 minutes at 250°F—the paper fades back to solid blue, erasing the writing.
Image A shows the paper before anything has been printed on it. Images D-F show text 10 minutes, one day, and two days after it has been printed, respectively. Image Credit: Wang et al., American Chemical Society (2017)
A UV light printer can either print white text on a blue background or be programmed to print the background itself instead, resulting in blue text against a white background. The nanoparticle coating can be used over and over again, allowing one sheet of paper to be reprinted 80 times before it has to be thrown away.
The researchers hope to one day be able to print in full color with a similar system. They are currently working on a laser printer compatible with their light-printable paper. Until it hits the market, you’ll have to content yourself with buying notebooks that can be erased in the microwave.