Response pattern of SnO2 sensor system for smoke of different origins

Abstract A sensor array of four SnO2 semiconductor thin-film (resistor type) devices has been tested for some gases and smoke of different origins. One pair of these sensors is activated by Ag, while the other pair is doped with Pd. The temperatures of the differently doped sensors are kept at approximately 120–140 and 180–200 °C, respectively. Smoke is generated from a certain amount (20 mg) of different materials (papers, wood, cigarettes, plastics, hair, etc.) by electric heating in an air-filled box. The sensors are sensitive for H2, CO (with Pd activation) and Cl2 and sulphur-containing gases (with Ag activation). Consequently, the signals of the Pd-activated sensors characterize the concentration of the smoke from the cellulose-based materials, while the Ag-activated sensors are sensitive for smoke from more complex organic materials.