Stability of solid electrolyte based thick-film CO2 sensors

Long-term stability is one of the major issues in the ongoing development of solid electrolyte based, screen-printed potentiometric CO₂ sensors. Though improvements of the sensor have been reported by several research groups, mostly due to changes in material combinations, little is referred to the influence of basic technological aspects in relation to the observable degradation effects. In view of this aspect potentiometric thick-film CO₂ sensors based on the electrochemical cell: Au, O₂, CO₂ |Ma₂CO₃-MeCO₃ (Au)||Na-β/β′′-Al₂O₃||Na₂Si₂O₅ SiO₂ (Au)|O₂, (CO₂), Au {Ma = Na or Li; Me = Ba or Ca} were investigated regarding the long-term stability at improved operating conditions. As previous works at the IKTS in Dresden have shown that the microstructure of the Na-beta-Aluminate (NBA) and the sensor preheating conditions have considerable influence on the stability, now different carbonate materials where evaluated regarding the influence on stability at improved operating conditions. So far, satisfying performance over more than 2000 h was demonstrated independent of the carbonate material used in the miniaturized CO₂ sensor.