RELATIVE HUMIDITY SENSOR AND METHOD

• US 20170248537A1
• Filed: 02/02/2017
• Published: 08/31/2017
• Est. Priority Date: 02/29/2016
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Serban, Bogdan-Catalin, Brezeanu, Mihai, Bulu, Octavian, Cobianu, Cornel P.
• Granted Patent: US 10,634,636 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 27/225 by using hygroscopic materials
• CPC Class Codes: G01N 27/226 Construction of measuring vessels; Electrodes therefor

Abstract

A relative humidity sensor is disclosed. The relative humidity sensor includes a first electrode and a second electrode disposed above a dielectric substrate. A humidity sensitive layer is disposed above at least one of the first electrode and the second electrode, where the humidity sensitive layer comprises a curable composition comprising cellulose acetate butyrate and a hydrophobic filler. In some embodiments, a dust protection layer is disposed above the humidity sensitive layer.

Claims

1. A relative humidity sensor, comprising:

a first electrode and a second electrode disposed above a dielectric substrate; and

a humidity sensitive layer disposed above at least one of the first electrode and the second electrode, the humidity sensitive layer comprising a curable composition comprising cellulose acetate butyrate and a hydrophobic filler.

2. The relative humidity sensor of claim 1, further comprising a dust protection layer disposed above the humidity sensitive layer.

3. The relative humidity sensor of claim 1, wherein the curable composition is a cured composition comprising cellulose acetate butyrate and a hydrophobic filler.

4. The relative humidity sensor of claim 1, wherein the humidity sensitive layer comprises about 5 to about 10 weight percent hydrophobic filler based on the total weight of the humidity sensitive layer

5. The relative humidity sensor of claim 1, wherein the hydrophobic filler is an organic compound.

6. The relative humidity sensor of claim 1, wherein the hydrophobic filler comprises lignin.

7. The relative humidity sensor of claim 6, wherein the humidity sensitive layer comprises about 5 to about 10 weight percent lignin based on the total weight of the humidity sensitive layer.

8. The relative humidity sensor of claim 6, wherein lignin has an average molecular weight from about 500 and about 1000 grams/mol.

9. The relative humidity sensor of claim 1, wherein the hydrophobic filler is an inorganic compound.

10. The relative humidity sensor of claim 9, wherein the inorganic compounds comprises at least one of calcium carbonate, barium sulphate, talc, synthetic fluorine mica, wollastonite, and Viton.

11. The relative humidity sensor of claim 1, wherein the humidity sensitive layer is disposed above the first electrode and the second electrode is disposed above the humidity sensitive layer.

12. The relative humidity sensor of claim 1, wherein the first electrode and the second electrode are interdigitated and the humidity sensitive layer is disposed above the first electrode and the second electrode.

13. The relative humidity sensor of claim 2, wherein the dust protection layer is porous.

14. A method of forming a relative humidity sensor, the method comprising:

depositing a first electrode on a dielectric substrate;

applying a composition to an upper surface of the first electrode to form a humidity sensitive layer, the composition comprising a curable composition comprising cellulose acetate butyrate and a hydrophobic filler;

depositing a second electrode on an upper surface of the humidity sensitive layer; and

depositing a dust protection layer on an upper surface of the second electrode.

15. The method of claim 14, further comprising curing the composition to form the humidity sensitive layer.

16. A method of forming a relative humidity sensor, the method comprising:

preparing a composition, the composition comprising a curable composition comprising cellulose acetate butyrate and a hydrophobic filler; and

depositing at least a portion of the composition on a dielectric substrate supporting a first electrode and a second electrode, wherein the first and second electrode are interdigitated, to form the relative humidity sensor.