A gold thin film, connected to a Wheatstone-bridge circuit, acts as an
NO gas sensor. The resistance of the gold film increases reversibly i
n the presence of 1 to 5 ppm of NO. Better response speed and sensitiv
ity are obtained at higher sensor temperatures in the range 100 to 200
degrees C. The optimum thickness of the gold film is 18-30 nm. The go
ld thin-film gas sensor can be used to detect parts per million of NO
in air without the combined use of any semiconductor material.