Flexible Magnetostrictive Sensor

• US 20130069639A1
• Filed: 09/19/2011
• Published: 03/21/2013
• Est. Priority Date: 09/19/2011
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: COBB, Adam C., DUFFER, Charles E., BARTLETT, Jonathan D.
• Granted Patent: US 8,653,810 B2
• Time in Patent Office: Days
• US Class Current: 324/209
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/083 Magnetic materials
• CPC Class Codes: H05K 2201/10151 Sensor
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.

Abstract

A flexible printed circuit board (PCB) magnetostrictive (MS) sensor comprising a first direct current (DC) bias PCB layer comprising a first plurality of conductive traces, a first alternating current (AC) PCB layer disposed on the first DC bias PCB layer, the first AC PCB layer comprising a first AC coil, a pocket PCB layer disposed on the first AC PCB layer, the pocket PCB layer to receive a strip of MS material, a second AC PCB layer disposed on the pocket PCB layer, the second AC PCB layer comprising a second AC coil, and a second DC bias PCB layer disposed on the second AC PCB layer, the second DC bias PCB layer comprising a second plurality of conductive traces. The traces from the first plurality of conductive traces are electrically coupled to traces from the second plurality of conductive traces.

Claims

1. A printed circuit board (PCB) magnetostrictive (MS) sensor comprising:

a first direct current (DC) bias PCB layer comprising a first plurality of conductive traces;

a first alternating current (AC) PCB layer disposed on said first DC bias PCB layer, said first AC PCB layer comprising a first AC coil;

a pocket PCB layer disposed on said first AC PCB layer, said pocket PCB layer to receive a strip of MS material;

a second AC PCB layer disposed on said pocket PCB layer, said second AC PCB layer comprising a second AC coil; and

a second DC bias PCB layer disposed on said second AC PCB layer, said second DC bias PCB layer comprising a second plurality of conductive traces, wherein traces from said first plurality of conductive traces are electrically coupled to traces from said second plurality of conductive traces, such that said electrically coupled traces are configured as a DC bias winding that circumferentially encompasses said first AC coil, said strip of MS material and said second AC coil.

2. The sensor of claim 1, wherein said PCB has a long axis and a short axis, said PCB short axis orthogonal to said PCB long axis, and wherein said PCB is flexible along said PCB long axis.

3. The sensor of claim 1 wherein said PCB is capable of bending along its long axis and conforming to a radius of curvature (Rc) of 0.02 feet or greater.

4. The sensor of claim 2, wherein said first AC coil and said second AC coil have long axes parallel to said PCB long axis and have short axes parallel to said PCB short axis.

5. The sensor of claim 2, wherein said first AC coil and said second AC coil have long axes parallel to said PCB short axis and have short axes parallel to said PCB long axis.

6. The sensor of claim 2, wherein said DC bias winding has a long axis orthogonal to said PCB long axis and parallel to said PCB short axis.

7. The sensor of claim 2, wherein said DC bias winding has a long axis parallel to said PCB long axis and orthogonal to said PCB short axis.

8. The sensor of claim 2, wherein said PCB long axis is an integer multiple of Pi (3.14) inches.

9. The sensor of claim 1, wherein said MS material is selected from the group consisting of Nickel, Iron-Cobalt Alloy and alloys of Tb, Dy and Fe.

10. The sensor of claim 1, further comprising a flexible insulation PCB layer disposed above and below each of said DC bias PCB layers and AC PCB layers, said flexible insulation PCB layer to provide electrical isolation and/or environmental protection.

11. The sensor of claim 2, further comprising physical and electrical attachment points along edges of said PCB short axis, enabling concatenation of a plurality of said sensors such that a composite sensor is provided, said composite sensor of length equal to an integer multiple of said PCB long axis.

12. The sensor of claim 11, wherein one or more of said electrical attachment points are disabled.

13. The sensor of claim 11, wherein said composite sensor is configured to circumferentially encompass a long axis of an object under test.

14. The sensor of claim 1, wherein said DC bias winding is driven with electrical pulses.

15. A method for employing a PCB implemented sensor for MS sensing, comprising:

providing a first DC bias PCB layer comprising a first plurality of conductive traces;

disposing a first AC PCB layer on said first DC bias PCB layer, said first AC PCB layer comprising a first AC coil;

configuring a pocket PCB layer on said first AC PCB layer;

inserting a strip of MS material into said pocket PCB layer;

disposing a second AC PCB layer on said pocket PCB layer, said second AC PCB layer comprising a second AC coil;

disposing a second DC bias PCB layer on said second AC PCB layer, said second DC bias PCB layer comprising a second plurality of conductive traces; and

electrically coupling traces from said first plurality of conductive traces to traces from said second plurality of conductive traces, such that said electrically coupled traces are configured as a DC bias winding that circumferentially encompasses said first AC coil, said strip of MS material and said second AC coil.

16. The method of claim 15, wherein said PCB has a long axis and a short axis, said PCB short axis orthogonal to said PCB long axis, and wherein said PCB is flexible along said PCB long axis.

17. The method of claim 15 wherein said PCB is capable of bending along its long axis and conforming to a radius of curvature (Rc) of 0.02 feet or greater.

18. The method of claim 16, wherein said first AC coil and said second AC coil have long axes parallel to said PCB long axis and have short axes parallel to said PCB short axis.

19. The method of claim 16, wherein said first AC coil and said second AC coil have long axes parallel to said PCB short axis and have short axes parallel to said PCB long axis.

20. The method of claim 16, wherein said DC bias winding has a long axis orthogonal to said PCB long axis and parallel to said PCB short axis.

21. The method of claim 16, wherein said DC bias winding has a long axis parallel to said PCB long axis and orthogonal to said PCB short axis.

22. The method of claim 16, wherein said PCB long axis is an integer multiple of Pi (3.14) inches.

23. The method of claim 15, wherein said MS material is selected from the group consisting of Nickel, Iron-Cobalt Alloy and alloys of Tb, Dy and Fe.

24. The method of claim 15, further comprising disposing a flexible insulation PCB layer above and below each of said DC bias PCB layers and AC PCB layers, said flexible insulation PCB layer to provide electrical isolation and environmental protection.

25. The method of claim 16, further comprising providing physical and electrical attachment points along edges of said PCB short axis, enabling concatenation of a plurality of said PCB sensors such that a composite sensor is provided, said composite sensor of length equal to an integer multiple of said PCB long axis.

26. The method of claim 25, further comprising disabling one or more of said electrical attachment points.

27. The method of claim 25, further comprising configuring said composite sensor to circumferentially encompass a long axis of an object under test.

28. The method of claim 15, further comprising driving said DC bias winding with electrical pulses.