What is the operating principle of the CO2 sensor?

The CO2 sensor is a chemical optical sensor utilizing the acidic nature of CO₂ for detection. 

It consists of a gas-permeable membrane in which a pH-sensitive luminescence dye is immobilized together with a buffer and an inert reference luminescent dye. CO₂ permeating into the membrane changes the internal pH of the buffer.

With this changes the luminescence of the pH-sensitive dye. Together with the inert reference dye internal referencing is made for detection of the luminescence lifetime of the sensor. 

The measurement signal detected by the pCO₂ mini correlates to the partial pressure of CO₂ ambient.

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