PURPOSE: To prevent the degradation in characteristics even in polluting atmospheres by coating the surface of a thermistor with an oxidative catalyst.
CONSTITUTION: The surface of a thermistor element 11 the lead wires whereof 13 are connected to a pair of thermister holding lead parts 24 is coated with an oxidative catalyst 12. Then, at the time of detecting pressure in the state that the temperature of the thermistor element 11 is held raised by flowing current to the thermistor element 11 through the holding lead parts 24, the org. materials scattering to the element 11 and reburn and evaporate by the effect of the oxidative catalyst 12 on the surface of the element 11, and do not stick on the element 11. Hence, the change in the characteristic of the element 11 owing to the sticking of org. materials is prevented. The catalysts prepd. by adding a small amount of platinum group elements to the basic compositions of [(γ-MnO2)+(Zn-Mn-FeOx)+(a -Al2O3, zeolite)] for oil smoke etc., and [(γ-MnO2+(Zn-Mn-FeOx)+(a -Al2O3, zeolite)] for carbon etc. are adequate as the oxidative catalyst 12.
INABA RITSUO
KASAHARA MASAO
