Giant magnetorestive sensors and sensor arrays for detection and imaging of anomalies in conductive materials
First Claim
1. An apparatus for performing non-destructive evaluation of a material, said apparatus comprising:
- at least one magnetic field generator means, comprising an electrically conductive coil having a principal axis, for applying a magnetic field to the material, thereby inducing in the material an induced magnetic field;
at least one giant magnetoresistance sensor, having a sensitive axis, proximate to said generator means and responsive to said induced magnetic field; and
means, in communication with said at least one giant magnetoresistance sensor, for detecting changes in resistance in said at least one giant magnetoresistance sensor;
wherein said sensitive axis is disposed substantially orthogonal to said principal axis of said coil, whereby said sensitive axis is unaligned with said applied magnetic field.
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Accused Products
Abstract
An apparatus and method for detecting defects in electrically conductive materials. A detection method and apparatus are provided for using applied magnetic fields to induce magnetic fields in the material under test, and then directly detecting changes in the induced magnetic field attributable to corrosion, cracks, flaws, or anomalies in the material under test. The invention features the use of one or more giant magnetoresistance sensors to detect directly the changes in the induced magnetic field, which changes provoke a response in the giant magnetoresistance sensors in the form of a change in resistance signal. The apparatus may be configured in various ways, including absolute field detection and differential field detection configurations, with either passive or active field compensation, and single sensor or multiple sensor arrays. A plurality of giant magnetoresistance sensors may be disposed upon a single substrate, or on multiple substrates. The invention includes method for performing detection by use of giant magnetoresistance.
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Citations
24 Claims
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1. An apparatus for performing non-destructive evaluation of a material, said apparatus comprising:
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at least one magnetic field generator means, comprising an electrically conductive coil having a principal axis, for applying a magnetic field to the material, thereby inducing in the material an induced magnetic field; at least one giant magnetoresistance sensor, having a sensitive axis, proximate to said generator means and responsive to said induced magnetic field; and means, in communication with said at least one giant magnetoresistance sensor, for detecting changes in resistance in said at least one giant magnetoresistance sensor;
wherein said sensitive axis is disposed substantially orthogonal to said principal axis of said coil, whereby said sensitive axis is unaligned with said applied magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for performing non-destructive evaluation of a conductive material, said apparatus comprising:
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at least one magnetic field generator means for applying a magnetic field to the material, thereby inducing in the material an induced magnetic field; at least one giant magnetoresistance sensor proximate to said generator means and directly responsive to said induced magnetic field, said sensor having a sensitive axis; and means for detecting changes in resistance in said at least one giant magnetoresistance sensor due to said induced magnetic field; wherein said field generator means comprises a conductive winding wrapped about a ferrite core, and said at least one giant magnetoresistance sensor comprises at least two giant magnetoresistance sensors surrounded by said ferrite core with the sensitive axis of at least one of said giant magnetoresistance sensors disposed substantially parallel to a sensitive axis of at least one other of said giant magnetoresistance sensors.
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15. An apparatus for performing non-destructive evaluation of a material comprising;
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at least one magnetic field generator means for applying a magnetic field to the material, thereby inducing in the material an induced magnetic field; a plurality of giant magnetoresistance sensors electrically interconnected in an array upon at least one substrate proximate to said generator means and responsive to said induced magnetic field; means for detecting changes in resistance in said plurality of giant magnetoresistance sensors due to said induced field; and means for generating a compensative magnetic field counteractive to said applied magnetic field; wherein said field generator means comprises a substantially planar conductive drive sheet and said means for generating a compensative magnetic field comprises a substantially planar conductive compensating sheet substantially parallel to said drive sheet, and wherein said giant magnetoresistance sensors are disposed between said drive sheet and said compensating sheet. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification