ABSTRACT
Semiconductor metal oxide gas sensors have undergone extensive development during the last decades following the invention of the original tin oxide sensor by Taguchi.1,2 Their operating principle is based on the measurement of changes in the electrical conductance of a metal oxide lm, resulting from physicochemical reactions with gas molecules adsorbed on its surface, which can be directly correlated to the gas concentration.3 While tin dioxide is the most widely employed material for gas sensors, because it is sensitive to practically all the toxic and inammable gases of interest, various other metal oxides may be used to obtain better sensitivity and selectivity to specic gases. Furthermore, the effects of interferences due to the presence of different gases can be largely suppressed by an appropriate choice of the sensor operating temperature.
