German scientists have proposed to use for sun protection sensitive to the ultraviolet dyes that change color depending on the time and intensity of exposure to sunlight. The dyes they put on the bracelets, tattoos, fabric patches, glasses and contact lenses: they can be scanned into a mobile application that tells the user that should move to the shade or to use other means of protection. Article published in Advanced Optical Materials.
Sunlight plays a very important role for human health: under the action of ultraviolet rays, for example, activates production of vitamin D, which, inter alia, responsible for strengthening bone and muscle tissue. However, prolonged exposure to the sun can cause the body great harm from redness and sun strike to burn and the development of melanoma.
It is therefore recommended to apply sun creams that create an effective barrier between UV rays and skin and also wear hats, sunglasses (the retina also may be affected by direct sunlight), and, if possible, chastely. Thus to reliably estimate how the sun could potentially cause harm is difficult.
Specifically for this up with gadgets that tell the user when the UV for it too much (for example, a couple of years ago a small sticker sensor was developed by L’oréal). Wolfgang Kurz (Wolfgang Kurz) from the Munich technical University and his colleagues propose to use more versatile way — paint, which changes color under the action of ultraviolet rays.
The researchers used two photosensitive agent (triphenylsulfonium and diphenyliodonium), which under ultraviolet light cause color change of the dye-based triphenylmethyl when it is oxidized by transfer of the hydride ion. Based on them, they made two of liquid paint and two patches are sensitive to UV light.