Heated Thick-Film Titania Exhaust Gas Oxygen Sensors

This paper discusses laboratory propane burner and engine dynamometer durability testing of thick-film titania sensors whose resistance changes several orders of magnitude in response to changes in the partial pressure of oxygen around the stoichiometric point. Development has progressed to where porous titania films applied to alumina substrates exhibit switching and delay times equal to or faster than those achieved with zirconia based oxygen sensors (currently used in automotive exhaust applications) even after 50,000 equivalent miles of engine dynamometer testing. The titania film has been combined with a thick film heater such that good switching can be achieved over at least a 200°C to 850°C exhaust gas temperature range. This provides better engine control during idle and low engine speeds, and flexibility in locating the sensor further downstream in the exhaust.