Combined immunoassay and magnetic immunoassay systems and devices for extended range of sensitivity

A device comprising;

• a conduit;
• a substrate including a planar top and bottom surface positioned within the conduit;
• a first electrochemical sensor positioned on the top surface of the substrate, the first electrochemical sensor including an immobilized layer of antibody configured to bind to an analyte;
• a second electrochemical sensor positioned on the top surface of the substrate and adjacent to the first electrochemical sensor;
• an opening in the bottom surface of the substrate extending to a region in the substrate below the second electrochemical sensor;
• a composite material including a binder and a particulate magnetic material, the composite material substantially filling the opening;
• a first dry reagent positioned within the conduit, the first dry reagent comprising magnetic beads including an immobilized layer of antibody configured to bind to the analyte;
• and a second dry reagent positioned within the conduit, the second dry reagent comprising signal antibodies configured to bind to the analyte, wherein the particulate magnetic material generates a magnetic field that is aligned with respect to the second electrochemical sensor.