| 摘要 |
PURPOSE:To improve the resistance to oxidation and to lower the cost by using a positive temperature characteristic(PTC) thermistor of a specific principal component as a heater of a gas sensor. CONSTITUTION:In order to obtain an NO2 gas sensor of a semiconductor type, two phthalocyanine films 22 of Cuba, FePc having Cu or Fe mixed in M are vacuum-deposited onto an Al2O3 insulating substrate 21, and then an Au electrode 23 and lead wires 24, 25 are attached thereto. A PTC thermistor 20 as a heater which has Ag electrodes 26 formed on both surfaces thereof is attached to the lower surface of the substrate 21. A lead wire 27 is connected to each electrode 26. For example, a thermistor of the composition (Ba0.76Pb0.24) TiO3+0.0015Dy2O3+0.0005MnO2 is employed for the thermistor 20 because the acting temperature is approximately 230 deg.C. The phthalocyanine gas sensor changes the conductivity when molecules of NO2 gas are adhered thereto, and therefore the concentration of NO2 gas can be measured. Since the heater itself is made of an oxide, it is resistant to oxidation and the heating temperature can be self-controlled to be constant. |
