Ultraviolet Sensor

The ML8511 sensor breakout is an easy to use ultraviolet light sensor. The MP8511 UV Sensor outputs an analog signal in relation to the amount of UV light it detects. This can be handy in creating devices that warn the user of sunburn or detect the UV index as it relates to weather conditions.

This sensor detects 280-390nm light most effectively. This is categorized as part of the UVB (burning rays) spectrum and most of the UVA (tanning rays) spectrum. The ML8511 sensor is very easy to use. It outputs a analog voltage that is linearly related to the measured UV intensity (mW/cm²). If your microcontroller can do an analog to voltage conversion, then you can detect the level of UV. Next, connect the following ML8511 breakout board to Arduino:

LAPIS Semiconductor developed the UV sensor ( ML8511A ) to detect a ultra violet rays with Si ( silicon ) device using the original SOI ( silicon on insulator ) technology.
The ML8511A measures the amount of ultra violet rayses contained in sunlight, and it is used for the equipment which displays the suntan by a ultra violet rays, the guidance for UV care of skin, etc. 
The ML8511A is ideal for mobile computing devices, such as a smart phone, a mobile phone, and a watch, at low power and a compact package (QFN).