Printer manufacturers will happily sell us very cheap printers because they profit many times over from also selling us very expensive ink cartridges. But what if your printer no longer required ink and in return the paper it used was a little more expensive? More expensive paper may sound like a negative, but what if each sheet of paper could be erased and reused 80 times?
That's what a team of researchers at the University of California at Riverside managed to create: a printer that replaces ink with light, and paper that contains the dye it needs to form print, but which can also be erased and reused many times over.
The research is led by Yadong Yin, a Professor of Chemistry at UC Riverside. The key to the process of printing without ink is the construction of the paper. It's a mix of nanoparticles formed from Prussian blue dye and titanium oxide applied to a sheet of standard paper.
The titanium oxide and blue dye are separate in each nanoparticle. However, with exposure to ultraviolet light the oxide in each particle moves to the dye and it turns white. So, for example, exposing the paper to a set pattern of ultraviolet light can form a character of the alphabet, making it appear printed on the page. The color print can be flipped so it's white on blue or blue on white.
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The printing system is accurate to a resolution of 5 microns, meaning it should be more than capable of competing with inkjet printers.
One limitation is the fact anything printed on this paper isn't permanent. It remains legible for at least 5 days, but then starts to fade and ultimately disappears. That process can be sped up by applying heat (250 degrees Fahrenheit for 10 minutes), and a sheet of paper can be reprinted at least 80 times. So it has the potential to save a considerable amount of money on ink and paper purchases, but isn't suitable for any document that needs to form a permanent record.
Yin's invention is not a commercial product yet, but could certainly find a market in the business sector where document printing is still a common task. How successful it can be depends on the price of the printers and just how much of a cost premium the paper carries.