portable uv sensor
Behind only smoking and obesity, exposure to UV radiation is a leading cause of preventable cancer cases in the UK1. With that in mind, I wanted to minimise my exposure during periods of dangerous intensity, while also spending as little time and money on protecting myself as possible.
To help with this, I made a portable sensor unit to help me decide in real time if the UV risk justified my effort, eliminating reliance on my phone for estimates and looking pretty too.
Front, with 0.92" OLED and photodiode:
Back, with charging port and menu/power button
It is powered internally from a 340mAh lipo, and run by an ESP32-C3 Mini. The sensor is combined with an op-amp to provide a measurable voltage from the small photocurrent, which varies linearly with radiation intensity.
Measurement precision is OK, with noise from the ADC on the ESP32 being the main source of error. The device has been calibrated against Met Office UV estimates, but not anything super accurate yet. Considering its use, this is fine.