AN4348

Cross-sensitivity, environmental variation, and

long-term output drift

DocID025166 Rev 1

19/25

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Cross-sensitivity, environmental variation, and long-

term output drift

Even if they are a good choice for many applications, electrochemical sensors are not

perfect. For example, they are generally sensitive to gases other than the targeted one. So,

depending on the environment targeted, cross-sensitivity values should be considered

even if the sensor is fitted with a filter.

Electrochemical sensors are also sensitive to temperature. For the same gas

concentration, the output reading is different if the temperature is different. This

dependency is illustrated in the sensor datasheet. With the help of a temperature sensor,

compensation is generally achievable at the micro-controller level.

Finally, pressure and humidity can cause the sensor to generate current spikes.

STMicroelectronics proposes miniature MEMS sensors to help improve the accuracy of an

application by compensating for these environmental parameter changes.

Drift in time of the sensor (sensitivity decreasing) should also be considered to maintain the

accuracy of the application. Consequently, regular calibrations are requested in the user

manuals of gas detectors.