An yttria-doped ceria-based oxygen sensor with solid-state reference

A self-contained, miniaturized, electrochemical-type solid-reference oxygen sensor is described which uses yttria-doped ceria (YDC) as an oxygen ion conducting solid electrolyte. Unlike conventional oxygen sensors, in which one side of the sensor needs to be directly exposed to the air reference, the oxygen sensor presented in this paper exploits a solid solution of 25mol% zirconia in ceria as the reference. Designing a combination structure, the sensing capability of this sensor is compared with a YSZ electrolyte oxygen sensor under the same conditions. This novel oxygen sensor exhibits an anomalous behavior in transition from rich-to-lean regimes where the polarity of the created voltage changes from a positive value of +500mV to a negative value of −150mV at λ = 1.01.