Physical principles of the zirconia exhaust gas sensor

A brief description of the zirconia exhaust gas sensor is given. The electrochemical principles of the sensor are reviewed. Starting from the Nernst equation, theoretical relations are derived which relate the galvanic potential of the sensor to the composition of the exhaust gas from an internal combustion engine. Theoretical curves of galvanic potential versus the inlet air-fuel ratio are shown and discussed. The utility of the zirconia exhaust gas sensor is defined in applications such as closed-loop engine control systems.