A team of Australian researchers has created a safe paper sensor capable of measuring sun exposure while taking into account the wearer’s skin tone and sunscreen use. The investigators used an inkjet printer to layer titanium dioxide and a food dye onto strips of paper. Titanium dioxide is safe and already used in sunscreen lotions, and when light hits it, it makes the dye next to it change color proportionally to the exposure. Sticking a flexible neutral density filter onto the paper that reflects one’s skin tone and the kind of sunscreen used, allows the device to provide personalized results.
