Thick-film solid electrolyte oxygen sensors using the direct ionic thermoelectric effect

A screen-printed direct ionic thermoelectric oxygen sensor based on 8 mol% Y2O3 stabilized zirconia (YSZ) is presented. Within the device, a temperature gradient is applied to the YSZ film via an integrated heater, and the resulting thermovoltage is measured. Theoretical considerations on oxygen ion conductors predict a well-defined dependency of the thermopower on the oxygen partial pressure p(O2). Experimental results on the present thick-film device are shown to agree well with the theory. Besides being intrinsically geometry-independent, the present potentiometric sensor showed no cross-sensitivity to a variety of reducing and oxidizing gases that are commonly present in the exhaust. In addition, a very low temperature dependence of the thermopower was observed.