Tungsten trioxide-based thick-film NO sensor: design and investigation

New thick-film WO3 based sensors for the determination of NO levels in steam power plants emissions developed and manufactured at the Laboratory of Electronic Engineering Materials (PTI, Minsk) have been tested in NO, CO or CPI, containing environments. WO3(Bi2O3) thick films have been used as NO sensitive elements in the sensors. The same metal oxide composition has been successfully applied as the base of built-in thick-film thermistors in the sensors developed. The sensors display high sensitivity to NO in air while remaining unresponsive to common interfering gases such as carbon monoxide or methane. It has been established during preliminary investigations that the sensor operating temperature has to be 300 degrees C, because the ambient temperature val ies between 250 and 290 degrees C in boiler shunt tubes where gas sensors are usually set. The characteristics of the sensors have been investigated at 300 degrees C in detail. The results of the investigations are discussed. (C) 1999 Elsevier Science S.A. All rights reserved.