Summer is right around the corner once again, and with it come days at the beach, picnics in the park, and lots of other opportunities to soak up the sun. But not too much sun, of course. Not only are sunburns painful, but they also elevate one’s risk of developing skin cancer in the future.
Most people would just put on some sunscreen, wear appropriate clothing, seek out some shade as the day wears on, and call it good. But that is not enough to satisfy Michael Baisch, who insists on having some hard data. As Baisch points out, there is more than just the UV-B radiation that causes sunburns out there. UV-A, for example, does not cause burns, but can lead to the development of melanoma.
Furthermore, hanging out at the beach is not the only time we are exposed to UV light. Sitting at home or work next to a window also exposes us to plenty of radiation — but you probably don’t rub on any sunscreen before sitting by a window, now do you? Maybe you should? Or perhaps the amount of radiation making it through to you is not enough to warrant that? Now you see why Baisch wants data. Without it, one can only guess.
To be really useful, any UV monitoring device needs to be portable so that it can go where its owner goes. For this reason, Baisch decided to build a UV monitoring system into a Flipper Zero. That gave him access to a microcontroller for data processing, a display for a user interface, and GPIO pins to interact with a sensor all in one little portable package.
As far as the sensor is concerned, an AS7331 Spectral UV Sensor on a SparkFun breakout board was selected. It is capable of independently measuring UV-A, UV-B, and UV-C radiation, so it is a pretty comprehensive solution. A custom PCB was designed to neatly connect the sensor breakout board to the Flipper Zero’s GPIO pins.
The sensor communicates via I²C, so interfacing it with the Flipper Zero was easy enough. But a great deal of configuration was necessary to get useful data from it. Moreover, many calculations had to be performed to turn the sensor measurements into something we can make sense of. So before the project was finished, Baisch had written a custom library for interfacing with the sensor to meet all of the project’s requirements.
After putting the finishing touches on the device and building a slick user interface, Baisch put it to use. And the results? Well, it is not the best news — you are probably far less safe than you think. You might want to consider upping your sun protection this summer — or maybe building your own copy of the Flipper Zero UV meter.This Flipper Zero has been turned into a UV radiation monitor (📷: Michael Baisch)
A closer look at the sensor (📷: Michael Baisch)
The adapter board (📷: Michael Baisch)