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    BM688 Heater Profile: Are they important?

    hhammer
    Member

    BM688 Heater Profile: Are they important?

    Recently I tried out the BME688, using the Bosch AI Software. For my understanding, the heater profiles do the follwing:
    The sensor heats up to a certain temperature, stays there for a certain time and takes the measurement. Then it heats up/cools down to next defined temperature and so forth.

    What is not clear to me yet, is the correlation between temperature and resistance for a certain mixture of gases FOR REPEATED MEARSUREMENTS.
    I know, that different compounds react differently at different temperatures with the surface of the sensor, but why would I for example want to measure the same temperature twice:

    200°C  250°C 350°C 250 °C

    Wouldn't it be sufficient to measure every temperature once  (and maybe vary the measuring time)? In the predefined heater profile I could also find some profiles with repeated measurements at low temperatures and some very short peaks with high temperatures. Are those peaks supposed to "burn" free the sensor?

     

    4 REPLIES 4
    BSTRobin
    Community Moderator

    Re: BM688 Heater Profile: Are they important?

    Hello hhammer,

    Could we know what object do you want to measure?

    hhammer
    Member

    Re: BM688 Heater Profile: Are they important?

    In general I try to detect VOCs but would also want to increase the field of application to COx. Does this have an influence to the heater profile?
    I was wondering which physical effect the profile has in general. I understand the influence of the sensor temperature, but not its correlation with time.

    BSTRobin
    Community Moderator

    Re: BM688 Heater Profile: Are they important?

    Hello hhammer,

    Heating profiles were designed and verified by lab tests, different kinds of gas may be recommended to use different heating profiles.

    hhammer
    Member

    Re: BM688 Heater Profile: Are they important?

    Thank you for the reply. I still don't quite understand why it would matter if I measure with two different profiles (e.g.150°C 180°C 220°C  and 180°C 220°C 150°C). Both profiles cover up the same temperatures, but in a different order. I would expect the measured resistence to be fixed at a certain temperature, without beeing effected by the measurement taken before or after.

    So it is still unclear, wh the order of temperatures should have an influence on the measured resistance of the sensor? Maybe someone has a hint for me to understand the correlation.

    Thanks!

     

     

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