Title: Humidity sensor

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Claims: What is claimed is:

1. A humidity sensor comprising:

a high-temperature resistant dielectric substrate;

a fired layer of cobalt oxide on a major surface of said substrate;

a pair of electrodes in contact with said cobalt oxide; and

a porous, non-wettable coating covering at least said cobalt oxide layer.

2. The humidity sensor as claimed in claim 1, wherein said coating is sputtered polytetrafluoroethylene.

3. The humidity sensor as claimed in claim 1, wherein said substrate is a high-alumina ceramic.

4. The humidity sensor as claimed in claim 1, wherein said substrate has first and second major surfaces, said oxide layer, electrodes and coating are on said first major surface, and additionally comprising a fired, thick film heating element on said second major surface.

5. A humidity sensor comprising:

a high-temperature resistant dielectric substrate;

a fired layer of cobalt oxide on a major surface of said substrate;

a porous, non-wetting coating of sputtered polytetrafluoroethylene over said fired layer;

a pair of electrodes in contact with said cobalt oxide; and

a fired, thick film heating element on the other major surface of said substrate.

Other info:

Inventors: Fraioli, Anthony V. (Essen Fells, NJ, US)

Application Number: 426953
Filing Date: 1973-12-13
Publication_date: 1976-06-01
Assignee: Plessey Incorporated (Melville, NY)
Primary Class(es): 338/35 200/61.06
Other Classes:
US Patent Ref:

2083732	Jun, 1937	Moore et al.	219/361.
2543384	Feb, 1951	Squier	338/35.
2806991	Sep, 1957	White	338/34.
2979828	Apr, 1961	Westeren	219/361.
3345496	Oct, 1967	DeLaney et al.	338/35.
3478191	Nov, 1969	Johnson et al.	219/543.
3479257	Nov, 1969	Shaver	23/254.
3496336	Feb, 1970	Hingorany et al.	219/543.
3715702	Feb, 1973	Nicholas	338/35.
3868492	Feb, 1975	Taylor	219/203.

Other Refs:
Primary Examiner: Albritton, C. L.
Assistant Examiner:
Attorney: Burke; James J.