Enjoy the summer sun, but make sure that it doesn't burn you! Put sunblock everywhere. Yes, even there.
Sunscreenr is a new device invented by the startup Voxelight to make sure that you get complete coverage from your sunblock. It's a pocket-sized camera that looks for ultraviolet light. When that ultraviolet light is blocked--which is what sunblock does--then it shows up black on the camera. Whatever isn't black didn't get covered with sunblock. Mashable explains:
Inside Sunscreener is a 1.3 mp UV camera that looks for reflected UV rays. If the sunblock is doing its job, it absorbs the rays. As a result, any place where you did apply the sunblock will look, through the viewfinder, black — because it's not reflecting UV light — and the uncovered spots will look pale. If you are alone, you can record up to 30 seconds of video in the device and then watch back inside Sunscreenr to see if you missed covering any spots. Voxelight representatives tell me that this method will work on darker skin complexions as well, though the contrast will be somewhat diminished.
-via Ace of Spades HQ