Critical review of nitrogen monoxide sensors for exhaust gases of lean burn engines

The paper intends to establish a comprehensive state of the art of nitrogen monoxide sensors applicable to the exhaust gas of lean-burn engines. The drastic operating conditions imply similar requirements to the oxygen lambda gauge. To date, like for oxygen sensing, only solid electrolyte- and semiconductor oxide-based sensors can be considered for NO sensing. The results of an exhaustive literature search on these types of sensors permit to propose some directions of research, taking into account principles, materials and manufacturing technologies.