Method for detection of NOx in exhaust gases by pulsed discharge measurements using standard zirconia-based lambda sensors

Presented is a measurement approach to differentiate reliably exhaust gas components using standard zirconia-based thimble-type potentiometric lambda sensors. A self-discharge characteristic after applying different voltage pulses between the sensor electrodes is used as a measurement parameter which depends on the gas component and its concentration in the exhaust. The detection of NO in the lower ppm range is demonstrated. In addition, this approach allows significant improvements in the response and selectivity to NO compared to other investigated gases such as H2, C2H5OH, and a mixture of hydrocarbons. Therefore, this technique seems to be capable of enabling NO sensing in combustion exhaust with improved selectivity using standard lambda sensors.