Resistive NOx dosimeter to detect very low NOx concentrations—Proof-of-principle and comparison with classical sensing devices

Abstract

Increasingly stringent emission and immission legislations for oxides of nitrogen demand a reliable air quality monitoring. Sensing devices following the resistive gas dosimeter principle may be an option for reliable long-term detection of toxic and harmful analyte gases like NOx. The presented resistive NOx dosimeter meets these requirements. During NOx exposure, a NOx storage material (potassium and manganese oxides on γ-alumina) adsorbs selectively NOx and changes its resistance, with a resistance change being proportional to the amount of adsorbed NOx, which is proportional to mean concentration average over time, i.e., it measures the NOx dose. Since the time derivative of the resistance change is proportional to the actual NOx concentration it can be also used as a NOx sensor. Besides a proof-of-principle, this work also compares the resistive NOx dosimeter with commercially available semiconducting and electrochemical NO2 gas sensors.