Analog Sensors for Air Quality Monitoring

Hardware
1

I will have a Particle Boron device and I will use 4 analog sensors: CO, O, S02, NO2 for air quality monitoring.

Ex: The carbon monoxide (CO): https://www.spec-sensors.com/wp-content/uploads/2016/10/ULPSM-CO-968-001.pdf , The ozone (O): https://www.spec-sensors.com/product/ultra-low-power-analog-sensor-module-ozone/
, they says NOTE: High impedance output requires a buffer to connect to any
measurement device., my questions are:

  1. is Vgas the output and can be connected directly to Boron, or will I need something else??
  2. is it linear, I mean I understand Vgas will be the output and it will be giving from 0 to 3V and I think “0” represents “0ppm” and 3V will be “500ppm”, so if I have 1.5V of output, will be 250ppm? or should I take the equations from the paper?
    3)Could I connect an I2C ADC like https://www.adafruit.com/product/1085 to each sensor?

Thanks in advance.

2

Hi @jonamleonel -

I am not familiar with that specific sensor, but in my experience rule of thumb is it is same to assume if you use modules (and not components) there are no additional hardware required between the module and MCU. Else it would be besides the point to use the module I would guess :wink: Unless of course stipulated otherwise by Datasheet.

I found this video, it seems to covert your CO sensor. I would also suspect there might be some calibration required which is often the case, but not sure.

Hope it helps.

Regards, Friedl.

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The output should be connected directly to an ADC pin. Ideally you would use temperature when calculating concentration. Look at their library source code on Git, written for Arduino but still helpful. I played around with a few of these sensors a few years ago and found them very unstable.

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Thanks, what should I do to maintain them stables?

Any other recommendations about other air quality monitoring sensors (CO, SO2, O3, NO2)?

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I don’t know how or if you can get stable readings, I only dabbled with Spec’s CO and CO2 sensors.

I never found anything reliable at the hobbyist level. AlphaSense makes very high quality electrochemical gas sensors but they do not distribute directly to consumer and they are expensive. I guess it really depends on how critical your project is. If you want a general idea of gas presence, then low cost sensors may be ok.

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6

This is a really cool project !

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