UV light

New inks could add a degree of transience to tattoos, making them more like summer wear than permanent features. Called PhotoTat, the inks can be switched between almost invisible and brightly coloured states using different kinds of light.

I'm a bit of a flashlight hoarder. Bike lights, work lights, EDC lights, head lamps, even night vision ... I have far too many, but try as I might, I can't seem to get rid of them.

Scientists have developed a fully transparent skin sensor that accurately measures UV radiation, detecting light and converting it to electrical signals. So before the sun's rays reach damaging levels, a phone alert lets users know it's time to cover up.