Magnetic-field biosensor measuring a differential signal from at least two magnetic-field sensing elements

A magnetic-field biosensor comprising:

• a substrate;
• a plurality of magnetic-field sensing elements on the substrate, the plurality of magnetic-field sensing elements comprising:
• a first magnetic-field sensing element;
• and
• a second magnetic-field sensing element;
• an insulator on the substrate and the plurality of magnetic-field sensing elements;
• a receptor configured to attach to biological material, the receptor being attached to the insulator and directly above the first magnetic-field sensing element;
• and
• a deterrent layer on the insulator and configured to deter bonding of receptors, the deterrent layer being directly above the second magnetic-field sensing element,
• wherein the first magnetic-field sensing element is configured to detect a magnetic field from a magnetic nanoparticle attached to the biological material that is attached to the receptor, and
• wherein an output of the first magnetic-field sensing element and an output of the second magnetic-field sensing element are used to sense the magnetic field from the magnetic nanoparticle by reducing an effect of an applied magnetic field.

A magnetic-field biosensor comprising:

• a substrate forming a plurality of peaks comprising a first peak and a second peak, and forming a plurality of valleys, comprising a first valley, a second valley and a third valley;
• a plurality of magnetic-field sensing elements comprising:
• a first magnetic-field sensing element on a first peak of the substrate;
• and
• a second magnetic-field sensing element on a second peak of the substrate;
• an insulator on the substrate and the plurality of magnetic-field sensing elements;
• a plurality of deterrent layers configured to deter bonding of a biological material, the plurality of deterrent layers comprising:
• a first deterrent layer located on the first peak directly above the first magnetic-field sensing element, wherein the first peak is between the first valley and the second valley;
• and
• a second deterrent layer located on the second peak directly above the second magnetic-field sensing element, wherein the second peak is between the second valley and the third valley;
• and
• a plurality of receptors configured to attach to biological material, the plurality of receptor comprising:
• a first receptor attached to the insulator in the first valley;
• and
• a second receptor attached to the insulator in the second valley;
• and
• wherein the first magnetic-field sensing element receives a magnetic field, parallel to an applied magnetic field, from a first magnetic nanoparticle attached to the biological material that is attached to the first receptor,
• wherein the second magnetic-field sensing element receives a magnetic field, parallel to the applied magnetic field, from a second magnetic nanoparticle, the second magnetic nanoparticle being attached to the biological material that is attached to the second receptor,
• wherein an output of the first magnetic-field sensing element and an output of the second magnetic-field sensing elements are used to sense the magnetic field from the first and the second magnetic nanoparticles by reducing an effect of an applied magnetic field.