Effect of electrode interface structure on the characteristics of a thin-film limiting current type oxygen sensor

A thin-film limiting current type oxygen sensor with graded-composition layer electrodes has been developed. Sensor resistance was governed by the electrode interface resistance. However, it was not clear whether anode or cathode effects were dominant. In this study, three kinds of electrodes with different interface structures (laminated, mixed, and graded-composition layers) were applied to anode and cathode, and their influences on sensor resistance were investigated. The sensor using the graded-composition layer electrodes showed the lowest resistance, as well as excellent low-temperature activity and stability. The sensor with the laminated electrode for cathode and the graded-composition layer for anode showed interface resistance 50% lower than the inverse configuration. Anode performance was a governing factor in overall sensor resistance.