Resistive Multi-Gas Sensor for Simultaneously Measuring the Oxygen Stoichiometry ( λ ) and the NO x Concentration in Exhausts: Engine Tests under Dynamic Conditions.

Due to increasingly stringent limits for NO x emissions, there is now more interest than ever in cost-effective, precise, and durable exhaust gas sensor technology for combustion processes. This study presents a novel multi-gas sensor with resistive sensing principles for the determination of oxygen stoichiometry and NO x concentration in the exhaust gas of a diesel engine (OM 651). A screen-printed porous KMnO 4 /La-Al 2 O 3 film is used as the NO x sensitive film, while a dense ceramic BFAT (BaFe 0.74 Ta 0.25 Al 0.01 O 3-δ ) film prepared by the PAD method is used for λ-measurement in real exhaust gas. The latter is also used to correct the O 2 cross-sensitivity of the NO x sensitive film. This study presents results under dynamic conditions during an NEDC (new European driving cycle) based on a prior characterization of the sensor films in an isolated sensor chamber with static engine operation. The low-cost sensor is analyzed in a wide operation field and its potential for real exhaust gas applications is evaluated. The results are promising and, all in all, comparable with established, but usually more expensive, exhaust gas sensors.