Now if we can only get this in a wrist watch format for portability.

It seems to me this is pretty simple (still quite brilliant though) and should be easy enough to make into a wristwatch – maybe using one of those TI MSP430s that the launchpad comes with?

Thanks, Hackaday, for putting up my project! I don’t have a pure UV source to test the sensor, but I tested it using a UV filter. Then I took readings different light sources. I also compared to reported UV readings at solar noon to my measurements & it came out very close to the reported level of UV radiation.

@Derrick – yeah, this is a straightforward build, mostly it was UI work & entering the WHO data. One trick, though, was how I read the LED without an op amp – I got the idea for this Mitsubishi whitepaper (http://www.merl.com/papers/docs/TR2003-35.pdf).

I’m cautious to dynamically re-calc exposure because I don’t think skin is equally sensitive throughout an exposure, but I couldn’t find any research on what the exposure curve is. It would be pretty cool, though, and not hard to program.

This looks better:
Oregon Scientific EB612 Personal UV Monitor with Exposure Timer

An LED cannot be used as UV sensor, the acrylic is not UV transparent. Your just measuring (blue) light. Propeller is far overpowered, too. 1 UV-photo diode, an LED and 1 mikrocontroller plus a lithium battery can do pretty much the same. Not even need a resistor.

I’m rather disappointed that the first post wasn’t “Excellent”

otherwise very cool but a UVA + UVB sensor would probably work better i’m assuming?

I have to agree with Steve that using the Propeller for this is overkill. A simple PIC would’ve done the trick.

Cool idea for the project, but I wouldn’t trust those readings coming from a single blue LED if I’m going to be frying under the summer sun ;)