Giant magnetorestive sensors and sensor arrays for detection and imaging of anomalies in conductive materials

An apparatus for performing non-destructive evaluation of a conductive material, said apparatus comprising:

• 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.

An apparatus for performing non-destructive evaluation of a material comprising;

• 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.