The invention relates to a device to detect individual moving objects having very small dimensions. The position and orientation tracking system includes at least one magnetoresistance reference sensor attached to a fixed object, at least one magnetoresistance sensor attached to an object being tracked, and a processor coupled to the at least one magnetoresistance reference sensor and the at least one magnetoresistance sensor. When the anchor is in its expanded configuration, a load is applied to the anchor until it is optimally configured to accommodate a range of deflections while the anchor itself exerts a substantially constant force against the tissue. The lightly doped substrate will include a first heavily doped region of a first conductivity type formed in the substrate and a lightly doped layer of a first conductivity type disposed on the substrate and the first heavily doped region. The anchor is left in place with only one small screw hole to spackle.