Chemosensors for motor management systems of the future

The growing demands to reduce polluting emissions from motor vehicles can be satisfied only by using new concepts of engine management. These concepts require new chemosensors for their implementation. Their center piece is a new lambda probe for the improved monitoring of idling operation or cylinder fluctuations. Sensors are also required for monitoring catalytic converters and regulating the catalytic reactions of nitrogen oxides in the exhaust from Diesel engines. At Siemens, research is being pursued into new sensors for these applications. The sensors are based on the effect of the gases on the electrical conductivity of semiconducting metal oxides. The latter can be manufactured as a thin film by reactive sputtering, thus allowing their easy integration into microsensor systems. In addition to the fast lambda probe for cylinder-selective measurement, research is being focused on sensors for hydrocarbons, nitrogen oxides and ammonia. The laboratory investigations have led to the discovery of suitable metal oxides for detecting the relevant gases. Prototypes of the fast lambda probe with a response time of less than 10 ms and a constant operating temperature up to 1000°C have been successfully tested on engine test benches.