SIMULATION OF THE EFFECT OF FRACTIONAL DIMENSION ON TIN-OXIDE-BASED GAS SENSORS

The effect of the fractional dimension of a tin-oxide surface on the s ensing mechanism is studied by means of Monte Carlo simulation in the case of CO. The dimension of the active surface has been found to be c onnected to both the sensitivity and the recovery rate of sensor resis tance after CO removal. A method of producing fractal surfaces with di fferent dimensions is presented. Experimentally observed large recover y times are explained on the basis of a small fractal dimension. On th e other hand, the observed instabilities of tin-oxide-based thick-film gas sensors are explained by considering the change of surface dimens ion caused by local reduction of tin oxide in the presence of CO.