Printing Paper With Light Instead of Ink

Researchers from Shandong University, the University of California, Riverside and the Lawrence Berkeley National Laboratory have developed a UV light printable paper, which can be used by large-scale printers.

uv light

Do you still remember being a child and sharing your secrets with your best friends in invisible ink so that nobody else could read them? A new method developed by researchers from Shandong University, the University of California, Riverside and the Lawrence Berkeley National Laboratory seems to be quite similar to this approach. Their UV light printable paper, which can be used by large-scale printers, could save money and reduce pollution.

UV Light: The New Ink

The rewritable paper works quite easily, because the only secret to print with light lies in the color switching property of nanoparticles called redox dyes. The used nano-coating consists of Prussian blue, a non-toxic blue pigment that loses its color when it gains electrons, and titanium dioxide, a photocatalytic material that interacts with UV light. When ultraviolet light shines on paper, the titanium dioxide releases electrons that are absorbed by the Prussian blue. This causes the pigment to change its colors from solid blue to clear. The scientists are then able to use targeted UV light to write blue text on a clear background, which is easier to read than the other way round.

Printing With UV Light: Easy, Cheap and Sustainable

Once printed the paper retains its look for at least five days with high resolution. Through oxidation, it then slowly fades back to solid blue. To erase the content more quickly, the paper can be heated to 120°C for about 10 minutes. Light printable paper that has the same look and feel as conventional paper addresses the pain points in conventional paper production. The low material costs and the given possibility to rewrite the paper make it a sustainable substitute to traditional paper. Thus, this method is even more resource-efficient than the re-usable paper that can be printed on with water instead of ink we already presented on the blog.

Now, the scientists are taking the next steps. They are about to reduce its costs for commercial scale use and constructing a laser printer to work with this rewritable paper to enable fast printing. Further, they want to make this technology available for broader applications, because it might be useful for those involving temporary information such as newspapers, product life indicators and oxygen sensors.

What do you think: For which other industry could this new printing technology be a groundbreaking solution?