Abstract: The present invention teaches an ultraviolet active wristband. The ultraviolet active wristband is made of the same materials as any wristband already in the market. However, the present wristband has the intriguing propriety of changing color reversibly from clear to any visible color (violet, blue, red, orange, yellow . . . ) when exposed to an ultraviolet source. The wavelength interval of the ultraviolet source is ?250 nm-400 nm!. Therefore, it is also sensitive to the spectrum of ultraviolet sunlight that is ?290 nm-400 nm!. The active chemical is a photochromic substance such as spiropyrans, spiroxazines.

Abstract: An Ultraviolet detector based on the propriety of a photochromic composition in changing its color upon exposure to UV rays is described. The said photochromic composition contains a spiropyran or a spiroxazine molecule previously dissolved in a non-polar solvent such as toluene, cyclohexane, then mixed to clear plastics to be incorporated in any item e.g. watch, credit card, sunscreen bottle cap. The present UV sensor can also be used as a sun shading technique on a windshield of an automotive vehicle.