The hardware has a laser light scattering sensor for particulate matter and 4 electromechanical sensors for carbon monoxide, nitrogen dioxide, sulfur dioxide and ozone (these sense the six parameters that are recognized as having significant health impact by multiple countries.) These sensors have2-yearear lifespan, so they are installed in sockets for easy replacement, and if needed, you can swap to different sensors to detect different things. The PCBs for the hardware are separated into a WiFi version and a LoRaWAN version and the software runs on an ATMega328 – the PCB has the standard six-pin ISP connection for programming.
The data collected is sent to a server where it is adjusted based on the unit’s calibration parameters and stored in a database per sensor. This makes servicing the sensors at the end of their life easier as all that’s required is replacing the sensors in the unit and changing the calibration parameters stored for that unit, the software changes are required. The server offers the data via a RESTful API so that building dashboards with the stats and charts become easy.
[Radu] used an off the shelf module as the first prototype and attached it to a car while driving around. He used this to test out the plan and work on the server. He then proceeded to designing the PCB hardware and the enclosure for the final unit. This work is an extension of [Radu]’s previous work, spotlit here in the 2015 Hackaday Prize, but also check out this project to put air quality sensors in the classroom.
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