Inkless Paper Discovered, Printed With Light & Reused 80 Times

Yadong Yin, a professor of chemistry at the University of California at Riverside, along with his team of researchers introduced an innovative and revolutionary type of inkless paper that is printed with light, erased by heating and can be reused 80 times.

The vast majority of the general population depends on wood-based paper to print documents and to jot down notes. Printers use ink cartridges to print out letters, symbols, pictures or illustrations onto a piece of paper and individuals use pens and pencils to create marks on paper.

However, various research initiatives and papers published by institutions including the NY Times revealed that paper can only be recycled four to six times through the traditional recycling process. Once paper is recycled four times, the quality drastically decreases, to the point where it is no longer usable for printers.

The American Forest and Paper Association also noted that only 63.4 percent of paper are recovered for recycling. That means, not only is 36.6 percent of paper left unrecycled but the possibility of the 63.4 percent of paper to be recycled four to six times is substantially low.

Essentially, the type of paper invented by Yin is a coating layer placed on top of a normal piece of paper. The coating is composed of nanoparticles made up of chemical analogues and titanium oxide which reacts to ultraviolet light in a specific way. Once ultraviolet light is shed upon the coating layer, electrons from titanium oxide moves away to the chemical analogues, allowing the blue coating layer to turn white.

Texts or symbols can be printed on top of the coating layer by shedding ultraviolet light into certain shapes. Once light goes through a shape, letters and symbols are immediately printed onto the coating layer.

An interesting element of this revolutionary printing process is that the paper can be reused if heated to 120 Celsius. Unlike the traditional recycling process, the resetting process of the coating takes 10 minutes. As soon as the coating layer is heated and left to cool, it can be reused 80 times to print letters or symbols.

In a study entitled “Photocatalytic Color Switching of Transition Metal Hexacyanometalate Nanoparticles for High-Performance Light-Printable Rewritable Paper,” Yin stated:

“Developing efficient photoreversible color switching systems for constructing rewritable paper is of significant practical interest owing to the potential environmental benefits including forest conservation, pollution reduction, and resource sustainability. This novel system can serve as an eco-friendly alternative to regular paper in meeting the increasing global needs for environment protection and resource sustainability.


As seen in the photograph, a coating layer of nanoparticles can be placed on top of a piece of paper and print letters or symbols using ultraviolet light. If this solution or technology becomes commercialized, people can potentially place the coating layer on certain parts of a piece of paper or a document to print out letters or symbols without having to replicate printed documents.


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