CO 2 monitoring with solid state electrolyte devices based upon Na 2 CO 3 /BaCO 3

Methods for continuous measurements of CO2 are of interest, e.g., in emission control, green house application, control of air quality in houses and automobiles. We give an overview on the status of techniques based upon the use of alkali carbonates for solid state electrochemical sensors, and we present new results which aim at estimating their performance and long-term stability in different environments. These results concern the sensitivity, the response times and their dependence on temperature and partial pressure of O2 and CO2, as well as the mechanism of gas interaction processes at the electrodes. A brief comparison is given of characteristic properties of these solid electrolyte sensors and of presently available other sensors operating with different transducer principles.