Abstract: A method of making a high efficiency magnetic sensor for determining the presence or amount of an analyte in a test sample. The method typically includes providing a sensing device with a magnetic sensing element, exposing the sensing device to a fluid test medium suspected of containing an analyte and monitoring the resistance of the magnetic sensing element to detect any change in the electrical resistance of the magnetic sensing element in response to the immobilization of a magnetizable particle. The magnetic sensing element comprises at least one planar layer of electrically conductive ferromagnetic material having an initial state in which the material has a circular magnetic moment within the plane of the layer, a means to immobilize a magnetizable particle at a point along an axis that is perpendicular to the plane of the layer and passes through the center of the circular magnetic moment, and a means for detecting the change in the electrical resistance of each magnetic sensing element.

Abstract: A method of ion implantation using oxygen backfill and a modified surface layer formed therefrom are provided. The method of ion implantation includes the steps of placing a substrate metal in an ion implantation vacuum chamber, introducing oxygen into the ion implantation vacuum chamber and directing a beam of ions at the substrate metal. The modified surface includes a substrate metal and implanted atoms at a surface of the substrate metal. The implanted atoms are integrated with the substrate metal. The substrate metal has an implanted atom concentration of at least 5 atomic % to a depth of over 250 Å.