Devices, systems, and methods for sensing moisture

• US 6,965,708 B2
• Filed: 10/04/2002
• Issued: 11/15/2005
• Est. Priority Date: 10/04/2002
• Status: Expired due to Fees

• Current Assignee: Luna Innovations, Inc.
• Original Assignee: Luna Innovations, Inc.
• Inventors: Luo, Shufang, Sucheta, Artur, Liu, Yongcheng, Elster, Jennifer L.
• Primary Examiner(s): Ullah, Akm Enayet
• Assistant Examiner(s): Wood, Kevin S.
• Application Number:
  US10/264,507
• Publication Number:
  US 20050105841A1
• Time in Patent Office: 1,138 Days
• Field of Search: 385/12, 385/13, 385/37, 385/147, 385123-128, 250/227.14, 250/227.17, 250/227.18, 340555-557, 73 73- 77
• US Class Current: 385/12
• CPC Class Codes: G01N 2021/7723 Swelling part, also for adsorption sensor, i.e. without chemical reaction
• CPC Class Codes: G01N 21/774 the reagent being on a grating or periodic structure
• CPC Class Codes: G01N 21/81 Indicating humidity
• CPC Class Codes: G02B 6/02095 Long period gratings, i.e. transmission gratings coupling light between core and cladding modes

Abstract

Various exemplary embodiments, devices, systems, and methods for sensing moisture are disclosed, including at least one moisture sensor that comprises an optical fiber, a long period grating formed in at least a portion of the optical fiber, and a layer of PEI bonded to the long period grating. One exemplary embodiment comprises a system for measuring humidity, the system comprising an optical fiber moisture sensor having a mono-layer of PEI covalently-bonded to an outer surface of said optical fiber, a processor coupled to said optical fiber moisture sensor, and a moisture indicator coupled to said processor.

Claims

1. A moisture sensor comprising:

an optical fiber;

a long period grating formed in at least a portion of said optical fiber; and

a layer of polyethylenimine (PEI) bonded to said long period grating.

2. A fiber optic moisture sensor having a covalently-bonded polyethylenimine (PEI) mono-layer.

3. An optical fiber moisture sensor having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber.

4. A mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of an optical fiber moisture sensor.

5. A moisture sensor comprising:

an optical fiber; and

a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber.

6. The moisture sensor of claim 5, wherein a molecular weight of said polyethylenimine (PEI) is within a range of approximately 7500 to approximately 1,000,000.

7. The moisture sensor of claim 5, wherein a molecular weight of said polyethylenimine (PEI) is above 7500.

8. The moisture sensor of claim 5, wherein a molecular weight of said polyethylenimine (PEI) is less than 1,000,000.

9. A moisture sensor embedded in a building material, said moisture sensor comprising an optical fiber having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber.

10. A moisture sensor attached to a building material, said moisture sensor comprising an optical fiber having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber.

11. A moisture sensor associated with a structure, said moisture sensor comprising an optical fiber having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber.

12. The moisture sensor of claim 11, wherein said structure is a building.

13. The moisture sensor of claim 11, wherein said structure is a machine.

14. The moisture sensor of claim 11, wherein said structure is an equipment.

15. The moisture sensor of claim 11, wherein said structure is an aircraft.

16. The moisture sensor of claim 11, wherein said structure is a ship.

17. The moisture sensor of claim 11, wherein said structure is a vehicle.

18. The moisture sensor of claim 11, wherein said structure is a military equipment.

19. The moisture sensor of claim 11, wherein said structure is a storage vessel.

20. The moisture sensor of claim 11, wherein said structure is a pipeline.

21. The moisture sensor of claim 11, wherein said structure is a bridge.

22. The moisture sensor of claim 11, wherein said structure is an electrical conduit.

23. A system for measuring humidity, comprising:

optical fiber moisture sensor having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber;

a processor coupled to said optical fiber moisture sensor; and

a moisture indicator coupled to said processor.

24. A system for predicting mold growth, comprising:

optical fiber moisture sensor having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber;

a processor coupled to said optical fiber moisture sensor; and

a mold growth indicator coupled to said processor.

25. A system for predicting corrosion, comprising:

optical fiber moisture sensor having a mono-layer of polyethylenimine (PEI) covalently-bonded to an outer surface of said optical fiber;

a processor coupled to said optical fiber moisture sensor; and

a corrosion indicator coupled to said processor.

26. A method for fabricating a moisture sensor, comprising:

forming a long period grating in a core of an optical fiber; and

covalently-bonding a mono-layer of polyethylenimine (PEI) to an outer surface of a cladding of the optical fiber.

27. The method of claim 26, further comprising:

stripping a covering from the cladding in the vicinity of the long period grating.

28. The method of claim 26, further comprising:

saturating the core with hydrogen.

29. The method of claim 26, further comprising:

applying a mask to a portion of the core.

30. The method of claim 26, further comprising:

exposing an unmasked portion of the core to a refraction index-changing source of light.

31. The method of claim 26, further comprising:

exposing an unmasked portion the core to a source of ultraviolet light.

32. The method of claim 26, further comprising:

imprinting the long period grating onto the core.

33. The method of claim 26, further comprising:

forming the mono-layer of polyethylenimine (PEI).

34. The method of claim 26, further comprising:

annealing the core to remove excess hydrogen.

35. The method of claim 26, further comprising:

identifying a loss band of light transmitted past the long period grating.

36. The method of claim 26, further comprising:

exposing the moisture sensor to a variation in ambient humidity.

37. The method of claim 26, further comprising:

monitoring a loss band of light transmitted past the long period grating.

38. The method of claim 26, further comprising:

quantifying a change in a loss band of light transmitted past the long period grating.

39. The method of claim 26, further comprising:

correlating a change in a loss band of light transmitted past the long period grating with a moisture level.

40. The method of claim 26, further comprising:

indicating a moisture level.