LIMITING-CURRENT TYPE SURFACE MODIFIED GAS SENSOR BASED ON BETA''-ALUMINA FAST SOLID IONIC CONDUCTOR

A new type of limiting current solid state ionic gas sensor is presented. The sensor is based on the reaction of the gaseous species with the electroactive component under the condition of limited access of the gas by a kinetic barrier. This allows one to employ the available fast solid alkali metal, silver and copper ionic conductors at ambient, and moderately increased temperatures. Theoretical considerations are presented and compared to experimental results of this type of limiting-current surface modified solid state electrochemical chlorine gas sensors. A linear relationship between the electrical current and the gas concentration is observed. The device may be operated at low temperatures, is sensitive to low partial gas pressures and may also overcome problems of cross-sensitivity. Sensors for gases other than chlorine may be based on the same principles.