I have completed my project to modify a domestic air-quality monitor, ( AQM ), which retails for GBP15 in the UK, and turn it into a multi-sensor AQM. See also 5, 9 & 12 February.
The original AQM only has a Cubic PM1006 particulate matter sensor. The colour of an illuminated indicator changes, ( green, yellow or red ), with the PM2.5 ( 2.5 micron ) particle concentration in the air. I have retained this feature in my modified versions.
I fitted a 'D1 Mini ESP32' micro-controller board to read the sensors and send the measurements to a display for viewing. The display module is a 128x32 pixel OLED. The sensor types I chose are the CCS811 ( CO2 & TVOC ), ( see also 20 January ), and the AHT20 ( temperature C & relative humidity % ).
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| Internal view showing position of the main components |
I have made two versions of the multi-sensor AQM, suited to my intended use based on which sensors I fitted and with a display to give a direct readout.. The image above shows the internal layout of the PM1006/CCS811 version.
The PM1006/CCS811 version displays data for PM1, PM2.5, PM10, CO2 & TVOC. I shall be using this version in my workshop where TVOC could occasionally be present.
The PM1006/AHT20 version displays data for PM1, PM2.5, PM10, temperature and relative humidity. I shall deploy this one in the kitchen primarily for the particulate matter measurements ( presence of smoke, flour etc ), and also the humidity.
So, in two places at least, I'll have some knowledge of how clean the air is that I'm inhaling.
I've also written software for a third version with just the PM1006, ( as in the original AQM ), only displaying data for PM1, PM2.5 and PM10. It would just be a simple matter of uploading the software to either of the other two versions.
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| Version PM1006/CCS811 |
The 'D1 Mini ESP32' micro-controller board has built-in wifi. This opens up the future possibility of integrating the multi-sensor AQM into a 'smart home' network.
TVOC = Total Volatile Organic Compounds ( paint, solvents etc ).
