A CAPACITIVE CO2 SENSOR WITH ON-CHIP HEATING

A directly heated capacitive sensor for the detection of CO2 is presen ted. An organically modified silicate acts as the sensitive layer, whi ch changes its dielectric properties under exposure to CO(2)The sensor is designed for operating temperatures between 30 and 100 degrees C. At room temperature a heating power of 210 mW is required to produce a n operating temperature of 70 degrees C. The sensor is optimized with respect to a good temperature uniformity in the sensitive area. The ma ximum deviation from the mean value is less than 3.5% (operating tempe rature: 70 degrees C). Measurements in a gas atmosphere show that the response of the directly heated sensor is the same as the response of a sensor that is thermostatted in a temperature chamber.