I've recently been using several different gas sensors, some of which I have already mentioned. But I also wanted a 'Particulate Matter' ( PM ) sensor to detect microscopic solid particles in the air, particularly as I am frequently sneezing in my work-area ! Realising that such sensors are also used in home 'air-quality' monitors, I bought a very cheap one for about GBP15 to take apart. Refering to the image below, green indicates 'good' air quality; PM2.5 between 0 and 35 ugms/cubic metre.
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| The domestic air quality monitor I bought |
I removed the sensor from inside and identified the type as PM1006 made by Cubic. Searching for a data-sheet for more information, it is described as a LED Particle Sensor for detecting particles ranging in size from 0.3 to 10 microns. Especially interesting was to read that it has a built-in micro-controller which directly outputs the particle mass concentration in digital form, ( units of micro-grams per cubic metre ), as a serial bit stream at 9600bits/s which I should be able to hack in order to decode the data and display the concentration value. In fact a permanent numerical display would be a useful addition to the air quality monitor to supplement the changing colour of the visual effect.
Next time I'll be describing how I hacked the data.
micron = one millionth of a metre.
PM2.5 = Particulate Matter 2.5 micron ( reference particle size adopted internationally in particle concentration definitions of air quality ).
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