Described are embodiments to ensure that the equipment utilized to detect antigens is reliable and accurate. If it is determined that a read sensor is degraded a method of calibrating a read sensor of a read head is described. In one embodiment, a method of calibrating a magnetic read sensor includes measuring a first resistance of the magnetic read sensor upon an application of a forward bias current to the magnetic read sensor and measuring a second resistance of the magnetic read sensor upon an application of a reverse bias current to the magnetic read sensor. A calibration constant is determined based on at least the first measured resistance and the second measured resistance. In one embodiment the method further includes storing the determined calibration constant for the magnetic read sensor in memory. Further, in one embodiment the head module having the magnetic read sensor is swept over at least one nanoparticle to obtain a read response of the magnetic read sensor to the nanoparticle. The read response from the magnetic read sensor of the at least one nanoparticle is adjusted based on the determined calibration constant. Calibration of each individual read sensor allows for uniform read responses from each of the read sensors on a read head, and prevents unreliable an inaccurate detection of analytes due to sensor degradation.