CO2 Selective Potentiometric Sensor in Thick-film Technology

A potentiometric sensor device based on screen-printed Nasicon films was investigated. In order to transfer the promising sensor concept of an open sodium titanate reference to thick film technology, ￠ € sodium-rich ￠ € and ￠ € sodium-poor ￠ € formulations were compared. While the ￠ € sodium-rich ￠ € composition was found to react with the ion conducting Nasicon during thermal treatment, the ￠ € sodium-poor ￠ € reference mixture was identified as an appropriate reference composition. Screen-printed sensor devices were prepared and tested with respect to CO2 response, reproducibility, and cross-interference of oxygen. Excellent agreement with the theory was observed. With the integration of a screen-printed heater, sensor elements were operated actively heated in a cold gas stream.