Professor Andrew Mills and Dr Michael McFarlane, from the University of Stratchclyde, Scotland has come up with an ingenious invention with this colourful paper bracelet that changes from yellow to pink when UV rays have reached safe limits. The acid in the paper degrades and changes colour. There is a range of bands depending on skin tones and their limits. Swedish-based Intellego Technology is commercializing it with a launch for spring 2013. The simplest ideas are often the best, after all.