GMR biosensor with enhanced sensitivity

A sensor, comprising:

• a substrate;
• an integer plurality of M independent and substantially identical horizontally planar GMR sensor stripes formed on said substrate and horizontally disposed as separate elements on said substrate and electrically connected in a single, continuous series-only electrical circuit to form a linear, series connected serpentine horizontally disposed array of said separate, independent GMR sensor stripes, wherein said planar GMR sensor stripes are denoted successively 1 to M, each said planar GMR sensor stripe having a rectangular shape with a length dimension greater than a width dimension and wherein said width dimension is comparable to a diameter of small magnetic particles to be detected and wherein there is a sensitive magnetic bias direction along said length dimension resulting only from a combination of shape anisotropy and magnetostriction, and wherein the width dimension of each said planar GMR sensor stripe is bounded by a top widthwise edge and a bottom widthwise edge and wherein said length dimension is bounded by a left-side lengthwise edge and a right-side lengthwise edge and wherein said planar GMR sensor stripes are placed side by side and parallel to each other in a lengthwise direction in a common horizontal plane and aligned with their respective left-side and right-side lengthwise edges adjacent to each other, parallel to each other and separated from each other by a separation distance that is less than the diameter of a particle to be detected and wherein co-linear top widthwise edges of adjacent stripes denoted 1 and 2 are electrically connected by a conducting element and wherein co-linear bottom widthwise edges of adjacent stripes denoted 2 and 3 are electrically connected by a conducting element and wherein the remaining stripes from 3 to M are similarly connected so that the totality of stripes 1 to M form a linear serpentine array with a continuous electrically conducting pathway from a bottom widthwise edge of stripe 1 to a top widthwise edge of stripe M;
• whereby a common current entering at the bottom widthwise edge of stripe 1 and leaving from the top in said serpentine array runs in an opposite direction in any pair of adjacent stripes.