High-performance gas sensing of CO: comparative tests for semiconducting (SnO2-based) and for amperometric gas sensors

A comparison of the stability and sensitivity for two different sensor types (semiconductor Sn[O.sub.2] devices, amperometric electrochemical sensors) has been performed. Sensitivities and drifts in the signal and in the background for various concentrations of CO have been studied for thick-film Sn[O.sub.2] sensors (Pt and Pd doped) for a period in excess of 8 months. Similar performance data have been recorded for commercial amperometric sensors for a period in excess of 4 years. The two different sensor types investigated here were also compared to the well-known commercial Figaro TGS 822 sensor at similar concentrations. An objective approach for comparing different types of sensors has been developed using the 'analytical sensitivity'.