THE CHARACTERIZATION OF SEMICONDUCTOR GAS SENSORS - A CRITICAL COMPARISON OF IN-HOUSE, PREPRODUCTION AND COMMERCIAL DEVICES

More than fifty SnO2-based commercial, in-house and experimental gas s ensors have been characterised with respect to temperature, relative h umidity and ps concentration, including inter- and intra-batch variati ons. These comprise fifteen different designs which are hoped to offer improvements in performance over the devices presently used in underg round coal mines. The results obtained to date suggest that whilst com mercial sensors possess greater sensitivities than newer experimental and in-house devices, the latter display reduced susceptibility to the presence of water vapour in the atmosphere, and a moderate inter- and intra-batch spread in, for example, sensitivity and baseline resistan ce.