A highly sensitive atmospheric NOX sensor

Mitsubishi Electric Corporation is developing sensors that can detect atmospheric oxides of nitrogen (NOx) in concentrations at the parts-per-billion (ppb) level. Studies of gas-sensitive films and NOx adsorption/desorption mechanisms led to development of a surface acoustic-wave device with a chromium tetraphenylporphyrin film that selectively detects NOx concentrations in the ppb to tens of ppb range. This article reports on the aforementioned sensors, their operating principles and response characteristics.