Wireless open-circuit in-plane strain and displacement sensor requiring no electrical connections

• US 8,692,562 B2
• Filed: 08/01/2011
• Issued: 04/08/2014
• Est. Priority Date: 08/01/2011
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Woodard, Stanley E.
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): Alejnikov, Jr., Robert P
• Application Number:
  US13/195,251
• Publication Number:
  US 20130033271A1
• Time in Patent Office: 981 Days
• Field of Search: 324/629, 324633-636, 324/691, 324/719, 324/207.11, 324/207.22, 333/24.R, 235/449, 235/493, 737/60, 737/63, 737/81
• US Class Current: 324/629
• CPC Class Codes: G01L 1/14 by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
• CPC Class Codes: G01L 1/26 Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload

Abstract

A wireless in-plane strain and displacement sensor includes an electrical conductor fixedly coupled to a substrate subject to strain conditions. The electrical conductor is shaped between its ends for storage of an electric field and a magnetic field, and remains electrically unconnected to define an unconnected open-circuit having inductance and capacitance. In the presence of a time-varying magnetic field, the electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses. The sensor also includes at least one electrically unconnected electrode having an end and a free portion extending from the end thereof. The end of each electrode is fixedly coupled to the substrate and the free portion thereof remains unencumbered and spaced apart from a portion of the electrical conductor so-shaped. More specifically, at least some of the free portion is disposed at a location lying within the magnetic field response generated by the electrical conductor. A motion guidance structure is slidingly engaged with each electrode'"'"'s free portion in order to maintain each free portion parallel to the electrical conductor so-shaped.

Claims

1. A wireless in-plane strap and displacement sensor, comprising:

an electrical conductor adapted to be fixedly coupled to a substrate subject to strain conditions, said electrical conductor having first and second ends and shaped between said first and second ends for storage of an electric field and a magnetic field, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped defines an unconnected open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses, each of which has a frequency, amplitude and bandwidth associated therewith;

at least one electrically unconnected electrode having an end and a free portion extending from said end, wherein said end is adapted to be fixedly coupled to said substrate and said free portion is unencumbered, is parallel to, and is spaced apart from, a portion of said electrical conductor so-shaped, at least some of said free portion further being disposed at a location lying within said magnetic field response so-generated; and

a motion guidance structure slidingly engaged with each said free portion for maintaining each said free portion parallel to said portion of said electrical conductor so-shaped.

2. A wireless sensor as in claim 1, further comprising a magnetic field response recorder for wirelessly transmitting said time-varying magnetic field to said electrical conductor and for wirelessly detecting at least one of said frequency, amplitude, and bandwidth associated with said magnetic field response so-generated.

3. A wireless sensor as in claim 1, wherein said electrical conductor comprises a thin-film trace.

4. A wireless sensor as in claim 1, wherein said electrical conductor lies in a two-dimensional plane.

5. A wireless sensor as in claim 1, wherein said electrical conductor forms a spiral between said first and second ends thereof.

6. A wireless sensor as in claim 5, wherein each said free portion is at a non-zero angular orientation with respect to portions of said spiral.

7. A wireless sensor as in claim 1, wherein said at least some of said free portion overlaps a portion of said electrical conductor so-shaped.

8. A wireless sensor as in claim 1, wherein each said electrode comprises a linear electrode.

9. A wireless sensor as in claim 1, wherein said motion guidance structure is electrically non-conductive.

10. A wireless sensor as in claim 1, wherein said motion guidance structure comprises a sleeve fitted over each said free portion.

11. A wireless in-plane strain and displacement sensor, comprising:

a thin-film electrical conductor adapted to be fixedly coupled to a substrate subject to strain conditions, said electrical conductor having first and second ends and shaped between said first and second ends for storage of an electric field and a magnetic field, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped defines an unconnected open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses, each of which has a frequency, amplitude and bandwidth associated therewith;

at least one electrically unconnected linear electrode having an end and a free portion extending from said end, wherein said end is adapted to be fixedly coupled to said substrate and said free portion is unencumbered, is parallel to, and is spaced apart from, a portion of said electrical conductor so-shaped, at least some of said free portion overlapping a portion of said electrical conductor so-shaped; and

a motion guidance structure slidingly engaged with each said free portion for maintaining each said free portion parallel to said portion of said electrical conductor so-shaped.

12. A wireless sensor as in claim 11, further comprising a magnetic field response recorder for wirelessly transmitting said time-varying magnetic field to said electrical conductor and for wirelessly detecting at least one of said frequency, amplitude and bandwidth associated with said magnetic field response so-generated.

13. A wireless sensor as in claim 11, wherein said electrical conductor lies in a two-dimensional plane.

14. A wireless sensor as in claim 11, wherein said electrical conductor forms a spiral between said first and second ends thereof.

15. A wireless sensor as in claim 14, wherein each said free portion is at a non-zero angular orientation with respect to portions of said spiral.

16. A wireless sensor as in claim 11, wherein said motion guidance structure is electrically non-conductive.

17. A wireless sensor as in claim 11, wherein said motion guidance structure comprises a sleeve fitted over each said free portion.

18. A wireless in-plane strain and displacement sensor system, comprising:

an electrical conductor adapted to be fixedly coupled to a substrate subject strain conditions, said electrical conductor having first and second ends and shaped between said first and second ends for storage of an electric field and a magnetic field, said first and second ends remaining electrically unconnected such that said electrical conductor so-shaped defines an unconnected open-circuit having inductance and capacitance wherein, in the presence of a time-varying magnetic field, said electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses, each of which has a frequency, amplitude and bandwidth associated therewith;

at least one electrically unconnected linear electrode having an end and a free portion extending from said end, wherein said end is adapted to be fixedly coupled to said substrate and said free portion is unencumbered, is parallel to, and is spaced apart from, a portion of said electrical conductor so-shaped, at least some of said free portion further being disposed at a location lying within said magnetic field response so-generated;

a motion guidance structure slidingly engaged with each said free portion for maintaining each said free portion parallel to said portion of said electrical conductor so-shaped; and

a magnetic field response recorder for wirelessly transmitting said time-varying magnetic field to said electrical conductor and for wirelessly detecting at least one of said frequency, amplitude and bandwidth associated with said magnetic field response so-generated.

19. A system as claim 18, wherein said electrical conductor comprises a thin-film trace.

20. A system as in claim 18, wherein said electrical conductor lies in a two-dimensional plane.

21. A system as in claim 18, wherein said electrical conductor forms a spiral between said first and second ends thereof.

22. A system as in claim 21, wherein each said free portion is at a non-zero angular orientation with respect to portions of said spiral.

23. A system as in claim 18, wherein said at least some of said free portion overlaps a portion of said electrical conductor so-shaped.

24. A system as in claim 18, wherein said motion guidance structure is electrically non-conductive.

25. A system as in claim 18, wherein said motion guidance structure comprises a sleeve fitted over each said free portion.