Humidity sensor
AssigneeNgk Spark Plug Co., Ltd.
InventorsSatoshi Sugaya, Tetsuo Yamada, Noboru Ishida
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Abstract
A humidity sensor including an insulating substrate, and a lower electrode formed from a noble metal, a moisture sensitive layer formed of a porous body predominantly containing alumina and containing predetermined amounts of TiO2 and SnO2 and an upper electrode formed of a noble metal porous body successively formed on the insulating substrate. The upper electrode is connected to the moisture sensitive layer and a portion of the insulating substrate. Preferably, the lower electrode is formed of a porous body. More preferably, the lower and upper electrodes are formed from Pt. Furthermore, preferably, a heater and a temperature measurement resistor are provided in the insulating substrate and are located directly below the moisture sensitive layer.
Claims8
A humidity sensor for measuring the humidity of an atmosphere to which the humidity sensor is exposed comprising:
- an insulating substrate;
- and
- a lower electrode, a moisture sensitive layer and an upper electrode successively formed on the insulating substrate, said moisture sensitive layer having an electrical resistance which changes with a change in humidity and said humidity sensor providing a measurement of humidity based on the electrical resistance of said moisture sensitive layer,
- wherein the lower electrode comprises a noble metal porous body, the upper electrode comprises a noble metal porous body, the moisture sensitive layer is porous, and the upper electrode is joined to the moisture sensitive layer and a portion of the insulating substrate, and
- wherein a size of pores in the upper electrode is 0.5-20 μm, a size of pores in the lower electrode is 0.5-20 μm, a size of pores in the moisture sensitive layer is 0.05-0.2 μm, particles of ceramic are incorporated in an amount of 1-20 wt % into the upper electrode, particles of ceramic are incorporated in an amount of 1-20 wt % into the lower electrode, and one or both of the lower electrode and the upper electrode predominantly contains Pt.
Dependencies are inferred from the claim text.