Response of metal-oxide-silicon carbide sensors to simulated and real exhaust gases

Field effect devices based on catalytic metal-oxide-silicon carbide (MOSiC) structures can be used as high temperature gas sensors. The devices are sensitive to hydrocarbons and hydrogen and can be operated up to at least 900 °C, which make them suitable for several combustion applications. Simulated and real exhaust gases from a car engine have been studied at sensor temperatures from 200 to 650 °C, and it was found that the sensor signal is high for excess hydrocarbon and low for excess oxygen. The response time is less than 100 ms and only a small degradation of the devices was observed after several days of operation. The devices also react to changes of the gas composition in the fuel-rich and fuel-lean region. The devices show an interesting temperature dependence in the fuel rich region.