Wavelength-independent polymer/optical sensing apparatus and method

• US 4,749,856 A
• Filed: 05/29/1986
• Issued: 06/07/1988
• Est. Priority Date: 12/07/1983
• Status: Expired due to Fees

• Current Assignee: Monsanto Company (Bayer AG)
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Walker, George E., Fisher, William K.
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US06/868,628
• Time in Patent Office: 740 Days
• Field of Search: 250/227, 250/231 R, 374/161, 374/162, 374/106
• US Class Current: 250/227.11
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01K 11/18 of materials which change translucency

Abstract

An optical sensing device which incorporates a suitable optical sensor system, preferably a fiber optics system, with a suitable environmental sensitive polymeric material is presented. The polymeric material must be of the type which undergoes wavelength-independent changes in optical properties in response to environmental changes. Accordingly, preferred polymers include crosslinked, semicrystalline polymers, high strength amorphous polymers, and polymer blends. This novel combination will accurately and, at times, reversibly measure and detect temperature, humidity, pressure, position, radiation, flow, stress/strain, light, color, electric field, and a plurality of other properties with respect to changes in the environment.

Claims

1. A device for detecting environmental changes comprising:

fiber optical sensor means; and

an environmental sensitive polymeric material capable of undergoing a wavelength-independent change in optical properties in response to a change in the environment, said environmental sensitive polymeric material communicating with said fiber optical sensor means and said environment whereby a change in the environment which causes said optical change in the said polymeric material is sensed and indicated by said fiber optic sensor means.

2. The device of claim 1 wherein:

said environmental sensitive polymeric material undergoes reversible changes in optical properties in response to said change in the environment.

3. The device of claim 1 wherein:

said environmental sensitive polymeric material is a semicrystalline polymeric material.

4. The device of claim 1 wherein:

said environmental sensitive polymeric material is a crosslinked polymeric material.

5. The device of claim 1 wherein:

said environmental sensitive polymeric material is an amorphous polymeric material.

6. The device of claim 1 wherein:

said environmental sensitive polymeric material is a blend of an organic polymer and an additive which is a member of the group consisting of a wax, a cerol and an oil.

7. The device of claim 1 wherein:

said environmental sensitive polymeric material is a solution of at least two polymeric materials.

8. The device of claim 7 wherein:

said solution of polymeric materials is a solution selected from the group consisting of styrene-acrylonitrile copolymer (PSAN) with polymethyl/methacrylate (PMMA) and chlorinated rubber with ethylene vinyl acetale copolymer.

9. The device of claim 1 wherein:

said environmental sensitive polymeric material is a polymeric material selected from the group consisting of polycaprolactone, polypropylene, poly 1.4 butylene adipate, polyethylene oxide, polyethylene adipate, rubber modified polyvinylchloride and a wax extended ethylene vinyl acetate, acrylonitrile-butadiene-styrene (ABS), polymethyl/methacrylate (PMMA), rubber reinforced PMMA, natural rubber, poly tertiary butlystryrene and polyvinylbutyral.

10. The device of claim 1 wherein said fiber optic sensor means includes:

a fiber optic cable having at least one first light transmitting fiber and at least one second light transmitting fiber, said first and second fibers each having first and second ends;

a housing for said environmental sensitive polymeric material and for receiving the ends of said first and second light transmitting fibers;

light source means connected to said first light transmitting fiber; and

light detecting means connected to said second light transmitting fiber, said environmental sensitive polymeric material being disposed in said housing so that the light from said light source means carried by said first light transmitting fiber passes through said environmental sensitive polymeric material to said second light transmitting fiber.

11. The device of claim 10 including:

a gap between said first and second ends of said fibers and said environmental sensitive polymeric material.

12. The device of claim 11 including:

converter means connected to said light detecting means whereby light from said light source is converted into electrical output.

13. The device of claim 10 wherein:

said housing includes a reflector, said reflector and said first and second ends of said fibers being disposed on opposite sides of said environmental sensitive polymeric material whereby light from said first light transmitting fiber passes through said environmental sensitive polymeric material and is reflected back through said polymeric material to said second light transmitting fiber.

14. The device of claim 10 wherein:

said housing includes a reflector, said reflector and said first and second ends of said fibers being disposed on the same side of said environmental sensitive polymeric material, said reflector being spaced a selected distance from said fiber ends.

15. The device for detecting environmental changes comprising:

optical sensor means; and

an environmental sensitive polymeric material capable of undergoing a wave-length independent change in optical properties in response to a change in the environment, said environmental sensitive polymeric material communicating with said optical sensor means and said environment whereby a change in the environment which causes said optical change in the said polymeric material is sensed and indicated by said optical sensor means;

said optical sensor means including;

a housing for said environmental sensitive polymeric material, said housing including two opposing sides;

light emitting means spaced from one side of said housing; and

light detecting means spaced from the other of said opposed sides of said housing wherein light from said light emitting means passes through said environmental sensitive polymeric material to said light detecting means.

16. The device of claim 15 wherein:

said light emitting means is a light emitting diode (LED).

17. The device of claim 15 including:

converter means connected to said light detecting means whereby light from said light source is converted into electrical output.

18. A method for detecting environmental changes using a fiber optic sensor means which communicates with an environmental sensitive polymeric material, said polymeric material being capable of undergoing a wavelength-independent change in optical properties in response to a change in the environment, including the steps of:

providing a change to the environment which causes an optical change in said environmental sensitive polymeric material;

sensing said optical change with said fiber optic sensor means; and

indicating said sensed optical change with said fiber optic sensor means.

19. The method of claim 18 wherein:

the step of providing a change to the environment which causes an optical change in said environmental sensitive polymeric material comprises at least one of the environmental changes of temperature, humidity, pressure, stress, strain, radiation, solvent crazing, solvent swelling, direction, position, acceleration, and light.

20. The method of claim 18 wherein:

causing said environmental sensitive polymeric material to undergo reversible changes in optical properties in response to said change in the environment.

21. The method of claim 18 wherein:

said environmental sensitive polymeric material is a semicrystalline polymeric material.

22. The method of claim 18 wherein:

said environmental sensitive polymeric material is a crosslinked polymeric material.

23. The method of claim 18 wherein:

said environmental sensitive polymeric material is an amorphous polymeric material.

24. The method of claim 18 including the step of:

forming said environmental sensitive polymeric material as a blend of an organic polymer and an additive which is a member of the group consisting of a wax, a cerol and an oil.

25. The method of claim 18 wherein:

said environmental sensitive polymeric material is a solution of at least two polymeric materials.

26. The method of claim 25 wherein:

said solution of polymeric materials is a solution selected from the group consisting of styrene-acrylonitrile copolymer (PSAN) with polymethyl/methracrylate (PMMA) and chlorinated rubber with ethylene vinyl acetale copolymer.

27. The method of claim 18 wherein:

said environmental sensitive polymeric material is a polymeric material selected from the group consisting of polycaprolactone, polypropylene, poly 1.4 butylene adipate, polyethylene oxide, polyethylene adipate, rubber modified polyvinylchloride and a wax extended ethylene vinyl acetate acrylonitrile-butadiene-styrene (ABS), polymethyl/methacrylate (PMMA), rubber reinforced PMMA, natural rubber, poly tertiary butlystyrene and polyvinylbutyral.

28. The method of claim 18 wherein said fiber optic sensor means includes:

forming a fiber optic cable having at least one first light transmitting fiber and at least one second light transmitting fiber, said first and second fibers each having first and second ends;

forming a housing for said environmental sensitive polymeric material and for receiving said ends of said first and second light transmitting fibers;

connecting light source means to said first light transmitting fiber; and

connecting light detecting means to said second light transmitting fiber, said environmental sensitive polymeric material being disposed in said housing so that the light from said light source means carried by said first light transmitting fiber passes through said environmental sensitive polymeric material to said second light transmitting fiber.

29. The method of claim 26 including the step of:

forming a gap between said first and second ends of said fibers and said environmental sensitive polymeric material.

30. The method of claim 29 including the step of:

connecting converter means to said light detecting means whereby light from said light source is converted into electrical output.

31. The method of claim 28 wherein including the step of:

providing a reflector to said housing, said reflector and said first and second ends of said fibers being disposed on opposite sides of said environmental sensitive polymeric material whereby light from said first light transmitting fiber passes through said environmental sensitive polymeric material and is reflected back through said polymeric material to said second light transmitting fiber.

32. The method of claim 28 wherein:

said housing includes a reflector, said reflector and said first and second ends of said fibers being disposed on the same side of said environmental sensitive polymeric material with said reflector being spaced a selected distance from said fiber ends.

33. A method for detecting environmental changes using an optical sensor means which communicates with an environmental senitive polymeric material, said polymeric material being capable of undergoing a wavelength-independent change in optical properties in response to a change in the environment, including the steps of:

providing a change to the environment which causes an optical change in said environmental sensitive polymeric material;

sensing said optical change with said optical sensor means, said optical sensor means including a housing for said environmental sensitive polymeric material, said housing including two opposing sides, light emitting means spaced from one side of said housing, and light detecting means spaced from the other of said opposed sides of said housing wherein light from said light emitting means passes through said environmental sensitive polymeric material to said light detecting means; and

indicating said sensed optical change with said optical sensor means.

34. The method of claim 33 including the step of:

providing said light emitting means as a light emitting diode (LED).

35. The method of claim 33 including:

connecting converter means to said light detecting means whereby light from said light source is converted into electrical output.