Thick-film CO gas sensors

A gas sensor of SnO
2
-based materials has been made by thick-film technology utilizing hydrophobic silica as a binder. The technology can achieve a high productivity as well as a reduced humidity dependence and a sufficient mechanical strength of sensors. A thick-film sensor of SnO
2
incorporated with ThO
2
shows highly selective detection for CO gas, separated from H
2
gas; i.e., sensitivity to CO is 42 times higher than to H
2
at both gas concentrations of 50 ppm. An excellent humidity-independent sensitivity is also achieved.