Alex Mariakakis et al. 2020
Colour-changing stickers and hair dye that react to ultraviolet light could help people gauge when they’re at risk of sunburn.
Alex Mariakakis at the University of Washington in the US worked with a team at Microsoft to develop printable stickers that change colour from purple to light pink throughout the day to indicate cumulative exposure to UV light.
The patches resemble contain a reference colour scale to indicate UV exposure, as measured by UV Index hours, a standard measure of UV radiation.
The patches …
source: newscientist.com