There are wearables to track your exercise activity, food consumption and sleep habits. There are even wearables that want to be smartphones-lite. But never before has there been a portable tracker for daily sunlight exposure. That's a niche GoodLux is looking to fill with its SunSprite, a solar-powered, Bluetooth 4.0 wireless device with a Harvard Medical pedigree that's launching today on Indiegogo. And it's gone everywhere with me this past week in Barcelona as I've raced in and out of conference halls to cover Mobile World Congress. The SunSprite itself is quite small, about the size of a stick of gum, and requires no charger or USB connection as it's fully reliant on solar power. It simply records user's daily sunlight exposure and makes that progress available, via a series of LEDs in its center, with the press of one side-mounted button.