| 摘要 |
PROBLEM TO BE SOLVED: To provide a humidity sensor suppressing deterioration of a humidity sensitive layer and maintaining stable performance over a long period, even under an atmosphere to be measured contains toxic substances and a high temperature atmosphere. SOLUTION: The humidity sensor 1 is provided with an insulation substrate 11 comprising alumina, the humidity sensitive layer 13 having alumina, titania, tin oxide and the like with a prescribed mass ratio, a detection electrode (lower electrode 12 and upper electrode 14) comprising noble metal such as Pt and Au, and a protection layer 15 comprising metal oxide and composite oxide of either alumina, spinel or the like and is a porous body. The detection electrode can be the porous body, and the humidity sensitive layer is preferably the porous body. In addition, a heater 111 and a temperature measuring resistor 112 are provided in the inside of the insulation substrate, and is provided directly under the humidity sensitive layer in the inside of the insulation substrate.
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