Scientists come up with light ink that can be applied and washed up to 50 times

A team at UC Riverside University in California has created a unique light ink based on microscopic titanium crystals. When exposed to UV rays, they darken, and when in contact with oxygen, the ink oxidizes and disappears.



The developers themselves believe that their invention will help reduce paper waste. Ink is based on three components. The main component of the material is titanium dioxide TiO2. This semiconductor substance begins to darken after exposure to ultraviolet radiation due to charge separation and reduction of metal crystals. In this case, the darkening is eliminated due to oxygen, which oxidizes titanium and produces a reaction in the opposite direction. Using these properties, the scientists extended the darkening of TiO2, so they were able to maintain the color change.



As a dopant, the specialists used nitrogen from urea, and diethylene glycol was also added to the crystals, which kept the titanium dioxide in a darkened form. To obtain the inscription, the researchers needed only thirty seconds of exposure to ultraviolet light with a wavelength of up to 400 nm. It is noted that to obtain, you need not so much a powerful light source as you need its correspondence to the required wavelength. As a result, specialists were able to obtain a high-contrast image that disappears only when heated or oxidized. To extend the life of the print, you can use a special polymer film that protects against oxidation.

The ink is designed for fifty write and erase cycles without compromising color contrast. The development can be useful in areas where there is a need for reusable surfaces or you need to rewrite something many times, for example, for printing tickets for public transport, coupons and information screens.