Bulk acoustic wave resonator as a sensing platform for NOx at high temperatures

Diesel engines, generating harmful NOx, will be subjected to legislation that stipulates large reductions in emission levels beginning in 2007. For controlling emissions, a NOx sensor is needed to provide feedback to the engine management system. In this work, we take advantage of the high mass sensitivity of resonant sensors and the chemical reaction of barium carbonate (BaCO3) with NO2 gas as the basis for a sensor that can be used in such applications. We show that a resonant sensor based on quartz crystal microbalance (QCM) and BaCO3 is sensitive to NO2 at 300 °C and above, with ability to resolve different NO2 concentrations.