A method of performing an immunoassay for determining a concentration of an analyte in a biological sample comprising: dissolving a first dry reagent and a second dry reagent into the biological sample, wherein the first dry reagent comprises signal antibodies, the second dry reagent comprises capture antibodies immobilized on magnetic beads, and the signal antibodies and the capture antibodies are configured to bind to the analyte; forming a first complex of the signal antibodies and the analyte; forming a second complex of the first complex and the capture antibodies immobilized on the magnetic beads; contacting a first immunosensor with the biological sample comprising the first complex and the second complex to form a third complex localized on or near a surface of the first immunosensor, wherein the first immunosensor includes an immobilized layer of capture antibodies configured to bind to the analyte, and the third complex includes the first complex bound to the immobilized layer of capture antibodies; contacting a magnetic field localized around a second immunosensor with the biological sample comprising the first complex and the second complex such that the second complex is localized on or near a surface of the second immunosensor; applying a fluid to wash the biological sample from the first immunosensor and the second immunosensor, wherein the wash fluid comprises a substrate configured to react with the signal antibodies; measuring a first signal at the first immunosensor from a reaction of the substrate with the signal antibodies in the third complex that are localized on or near the surface of the first immunosensor; measuring a second signal at the second immunosensor from a reaction of the substrate with the signal antibodies in the second complex that are localized on or near the surface of the second immunosensor; and determining the concentration of the analyte in the biological sample from at least one of the first signal and the second signal. dissolving a first dry reagent and a second dry reagent into the biological sample, wherein the first dry reagent comprises signal antibodies, the second dry reagent comprises capture antibodies immobilized on magnetic beads, and the signal antibodies and the capture antibodies are configured to bind to the analyte; forming a first complex of the signal antibodies and the analyte; forming a second complex of the first complex and the capture antibodies immobilized on the magnetic beads; contacting a first immunosensor with the biological sample comprising the first complex and the second complex to form a third complex localized on or near a surface of the first immunosensor, wherein the first immunosensor includes an immobilized layer of capture antibodies configured to bind to the analyte, and the third complex includes the first complex bound to the immobilized layer of capture antibodies; contacting a magnetic field localized around a second immunosensor with the biological sample comprising the first complex and the second complex such that the second complex is localized on or near a surface of the second immunosensor; applying a fluid to wash the biological sample from the first immunosensor and the second immunosensor, wherein the wash fluid comprises a substrate configured to react with the signal antibodies; measuring a first signal at the first immunosensor from a reaction of the substrate with the signal antibodies in the third complex that are localized on or near the surface of the first immunosensor; measuring a second signal at the second immunosensor from a reaction of the substrate with the signal antibodies in the second complex that are localized on or near the surface of the second immunosensor; and determining the concentration of the analyte in the biological sample from at least one of the first signal and the second signal.