Gas Sensors with Porous Materials

Gas mixtures containing the analyte beside inert gases 

In all three cases, the measurement cell consists, schematically, of two porous electrodes (usually Pt) pressing a layer of the sensing material (Zhuiykov, 2007). 

O2 (g) + 4e (metal) - 20- (electrolyte) or, using the Kroger-Vink notation, 

The electromotive force of the cell is given by the Nernst equation  

Conductivity in solid oxide-type compounds can be associated to defect formation and oxygen absorption/desorption processes. The following defect-forming reactions are possible  

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