The Sensor principle which is usual for Rebreather and Nitrox-Analyser purposes is a shunt loaded fuel cell.
The cell delivers a current which goes abt. linear with ppO2, exponential with temperature. 10°C temperature increase mean abt. double current and so double burnout-speed of the fuel cell. The shunt-resistor is temperature dependant, it halfs it's resistance then the temperature increased abt. 10°C so that the Sensors Voltage stays constant when the Temperature changes (as long as there is no temperature gradiend across the sensor) . The Assemle of Fuel-Cell and Shunt is what is called "the Sensor" or "the Cell", the Temperature Compensation is inside, you will never see it as long as you don't Xray the Assemble.

This sensors measure the Oxygen-Partial-Pressure, so then you use them to analyse a gas for it's Oxygen Fraction you have to know its Pressure or have to do it at the same pressure you used during the calibration. Take this into account when designing / using a Nitrox-Analyser. Do not forget that there is no guarantee that a sensor is and stays exactly linear, so calibrate it close to the area where you want to use it.

Here an Example of a Sensor-Tripple of which two at the End of Live, and one still real perfect.

The Cells's Livetime is defined in Days at a given ppO₂ and a given Temperature, this means it is really no good Idea to store it at 1bar-ppO₂ and 40°C when you can also store it in Air at 10°C.

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http://Rebreather.de/rebreather/sensor.htm © Karl Kramer, 30.08.1999, Graph:2003