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    BME688 and CO2 measurement in hot and humid environment

    Meach
    New Poster

    BME688 and CO2 measurement in hot and humid environment

    Hello,

    I want to use the BME688 sensor in a sauna to monitor the air quality and CO2 concentration.
    The main aim is to know when the CO2 concentration gets too high and when I should bring fresh air into the room.

    The BME688 is rated to work up to 85degC so I placed the sensor inside the sauna itself.
    Outside the sauna I have another CO2 sensor, rated 60degC only, with a small airpump that bring air from the sauna and acts as a reference.

    To simulate people in the sauna, I use a CO2 cannister from which I release some gas from time to time.
    Right now the CO2 equivalent I am measuring with the BME688 seems totally off and very much influenced by the temperature and humidity. I do not see any correlation with the actual CO2 level that I am measuring with my other sensor.
    I add some graphs of some measurements I have been doing.

    I also have a BME688 evaluation kit and I tried to use the BME AI software to train an algorithm to detect CO2 from different sample set I recorded.
    Unfortunately the gas estimate I was measuring was stuck at 33% and barely not changing, no matter what is going on in the sauna.

     

    My questions are:
    - How sensitive to temperature and humidity is the BME688 sensor?
    - Can we measure pure CO2 with this sensor? Or does the CO2 equivalent is calculated from human breath only?
    - Is this sensor useable at all for my use case?


    I am using the BSEC library version 2.2.0.0 and use lower power mode (LP) for the sample rate.

    Cheers.

    CO2 comparisonCO2 comparisonTemperature and humidityTemperature and humidity

    3 REPLIES 3
    BSTRobin
    Community Moderator

    Re: BME688 and CO2 measurement in hot and humid environment

    Hi Meach,

    Sorry for the delay reply.
    1.The full range of the temperature sensor is 0~65 °. Can you test within this range?
    2.BME688 sensor is some sensitive to temperature and humidity;
    3.The sensor can test CO2 content in the air, not limited to human breath.
    4. We cann't understand that the reference CO2 value has been maintained at 500 for a long time. Can you explain it? In the figure, are the reference CO2 and the CO2 output from BME688 measured at the same time?

    2022-10-11_17h45_58.png

    BSTRobin
    Community Moderator

    Re: BME688 and CO2 measurement in hot and humid environment

    Hi Meach,

    Could you give feedback?

    BSTRobin
    Community Moderator

    Re: BME688 and CO2 measurement in hot and humid environment

    Since there was no feedback for a long time, we close this topic first. You could update feedback in the future if you have.

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