TIO2 THICK-FILM GAS SENSORS AND THEIR SUITABILITY FOR NO(X) MONITORING

The aim of our laboratory study was to test the possibility to use TiO2-based thick-film gas sensors for exhaust NO(x) monitoring. The lack of selectivity, being one of the main troubles with the semiconductor gas sensors, has been controlled and improved by doping the base material with trivalent additives (Al3+ and In3+). The other way to affect the selectivity and also the sensitivity of semiconductor gas sensors is to change the operation temperature of the sensor. The response measurements are performed in a temperature range of 400 to 550-degrees-C. The conductance response of the sensors is tested using both NO(x) (NO and NO2) and interfering gases CO, SO2 and O2. The concentration of NO, NO2, CO and SO2 cover the range from tens to hundreds of ppm.