It is not the first time that the development of a smart paper has been announced that, once used, can be erased on the spot and used again. Thus, at the end of 2014, the University of California, Riverside, presented a system that used chemical dyes and ultraviolet light to highlight the text that had been written on a special colored sheet. When it was heated, the message disappeared.
Three years earlier, the Taiwan Industrial Technology Research Institute had already shown an electronic paper that made it possible to easily remove content and reprint another one easily up to 260 times . Other techniques, like the one published in 2017 by Chinese and American scientists in Nano Letters , use photosensitive sheets that can be printed directly on with light. Over time, the message fades and the surface can be used again.
One of the problems with these technologies is, precisely, that the texts and images that are captured on these supports tend to fade in a short time. Another, which, in general, only allow the inclusion of monochrome motifs. Well, a group of researchers from different Chinese technology centers, coordinated by Qiang Zhao, an expert in organic electronics from Nanking University of Post and Telecommunications, has designed a new type of paper and a special ink that, when used together , not only make it possible for images and color texts to be displayed several times on the same sheet, but they also last for more than six months.
Cheaper and ecological
As explained in a study in the journal Nature Communications , after reusing one of these sheets eight times – a job that they consider conservative – they have estimated that the cost per printing of their system is approximately one fifth of that of inkjet that today They use a lot of printers .
The support they have developed is a multilayer sheet composed of several polymers on which a chemical substance has been applied that reacts with the metal salts used by the ink. When this happens, seven different colors are produced. During the process, Zhao and his colleagues used a conventional inkjet printer. Images and texts can be erased simply by adding another compound to the spread.
This same team of experts has presented another type of reusable paper that uses water as ink . The system, still in its early stages of development, only allows printing in one color, but reduces printing costs to a tenth of what is usual with the aforementioned injection system.
In their essay, the authors explain that, for centuries, paper has been the most important means of preserving data and extending civilization. “Although in the last two decades different electronic media have broken into our day to day, continues to be essential in the communication and dissemination of information. However, its use has a significant environmental impact,” they add. Now, they hope their advance will help alleviate the ecological footprint of current printing systems.
Reference: Dynamic metal-ligand coordination for multicolour and water-jet rewritable paper . Yun Ma et al. Nature Communications (2017). DOI: 10.1038 / s41467-017-02452-w
Image: Dean Hochman via Flickr / CC
