Re-Writable Paper: Light Can Be The New Ink
Campaigns on ‘Save trees’ would get a break if this invention of ‘Re-writable Paper’ comes into global usage. Being ‘re-writable’, this can reduce loads of waste that is generated annually entirely from the paper industry.
Re-writable paper is another significant invention in the context of improving conditions of pollution and excessive deforestation. This can be reused for about 20 times. Instead of using ink or graphite, ultraviolet light is used to print down content as well as images.
In Nature Communications, released on 2 December, 2014 Yadong Yin, University of California, Riverside has explained about new re-writable paper. Despite increased popularity as well as utilization of digital gadgets, Yin believes in convincing future of re-writable paper technology.
HOW DOES THIS WORK?
This re-writable paper works on chemical reactions of reduction and oxidation. The paper initially has the dye which is colored being oxidized. Paper is covered with nano-sized crystals of titanium dioxide — each around a billionth-of-a-meter in size. This colored paper is covered with words or images printed on a translucent base- like a stencil. To print the data, this paper surface is exposed to ultraviolet (UV) light. The UV light causes initiation of reduction reaction on the parts that are not covered by printing; hence decolorizing those portions. Thus, the segments that were covered by stencil remain colored.
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In this procedure dye is chemically reduced using ultraviolet light. It is the appreciable small size of nano-particles on the surface of paper that allow effective and easier movement of electrons; accelerating redox (Reduction-Oxidation) reactions. The electrons lost by other organic parts of this re-writable paper occupy holes, preparing the nano-crystals work again.
For reusing, the paper has to be made colored again. This is done by oxygen present in air. Oxygen attracts electrons and the paper becomes ready for using again. To avoid this process during or soon after the printing, special cellulose is added. It tends to reduce interaction of oxygen and dye. The printed stuff can remain intact for two or more days.
To reuse the paper at that instant, heating process is used. Oxidation can be activated at particular temperatures bringing back the entire paper in color in less than five minutes.
Research is still going on improving features and making this re-writable paper usable in ordinary lives. Advantages associated with using re-writable paper are its low cost and environmental benefits of course. Within few years of research and modifications, re-writable paper is expected to serve efficiently.
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“Many people would prefer to read news on conventional newspapers rather than tablet PCs,” says Yin. “Also, one does not need to worry about charging and maintaining batteries for re-writable paper. I believe there would be a strong demand for it.”
We all want such revolutionary inventions to perform effectively and alter choices at global levels. Comment down your views.
