A ZIRCONIA-BASED LAMBDA GAS SENSOR WITH PSEUDO-REFERENCE

A sensor operating on the potentiometric principle without the need for a stable reference gas is described. This was achieved by using a miniature zirconia pump-gauge device including a diffusion path between its internal volume and external atmosphere. A pseudo-reference oxygen partial pressure was generated within the internal volume and acted as a reference for potentiometric determination of the external oxygen partial pressure. The sensor was tested in the normalized air-to-fuel range 0.7 to 1.7 and displayed a characteristic similar to that of a conventional potentiometric sensor with a fixed stable reference, e.g. air.