We've all done it - spent a day in the sun and sought shelter before we're burnt - only to develop a lobster-esque sheen long after we're safely in the shadows.
In response to this most common of summer sun mishaps, students at Michigan Technological University have developed a patch that warns you when you're going to get burnt.
The skin adhesive patch is UV-sensitive. An image slowly disappears as it is exposed to more and more damaging rays.
Too much UV exposure causes ageing and contributes towards cancer
The developers have even taken into account different skin types, producing three different versions.
Crucially the patch is designed to be exposed to the same levels of sun cream and shadows as the wearer therefore giving an accurate picture of total UV damage.
Megan Frost, the teams co-advisor, said: "There are other personal UV monitors out there, but what makes this one unique is that it’s extremely simple and inexpensive."
The patches, which only cost 13 US cents apiece, have already won 'Best Overall Award in the Invention Disclosure Competition at Michigan Tech’s 2013 Undergraduate Expo'.
The project has been rewarding, says team member Caroline D’Ambrosio: “It’s great to actually make a working product.”