Self-calibrating electrochemical gas sensor

A self-calibrating electrochemical gas sensor with an online supervision of the gas sensor's function, sensor's sensitivity and sensor's response time is presented. It leads to an online electrical recalibration and an early detection of an aging dependant sensor failure by detection of the value of sensor's electrochemical active area.

Independent of the gas concentration to be measured, and without spoiling a running operation, the electrochemical active area determining the sensor's sensitivity and the sensor's response time is determined online by measuring the electrical impedance of the sensor.

The maximal relative error of the estimated sensitivity and the sensor's response time through the online impedance measurement is small in comparison with the error caused by aging without calibration.

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