Improvement of humidity dependence in gas sensor based on SnO2

A tin oxide-based gas sensor for detecting CH4 and i-C4H10 in a low gas con centration (200 ppm) was developed on the basis of "Hot Wire Type" gas sens or, which was sintered in a bead (0.55 mm empty set) to cover a platinum wi re (0.20 mm empty set) coil. The effect of oxides of Co, Cr, La or Ce on hu midity dependence of tin oxide was investigated. The oxides of Co and Cr ga ve a prominent stability for the sensor output to CH4 and i-C4H10 under the humidity change outdoors through a year. (C) 2000 Elsevier Science S.A. Al l rights reserved.