Figure 1.
Overview of the proposed magnetic correlated double sampling technique with a GMR biosensor. A set of capture antibody, analyte of interest, and detection antibody form a sandwich structure tethering MNPs to the surface. When current is passed through the field wire, an excitation field is generated (left), the output voltage is a superposition of the signal, 1/f noise, and offset. When there is no excitation (middle), the output voltage measures only the 1/f noise and the offset. If the time difference between the two measurements is sufficiently small, 1/f noise and offsets are highly correlated so the subtraction of the two contains only the signal of interest (right).