Detection of magnetic-based bio-molecules using MR sensors

Results from micromagnetic modelling performed on magnetoresistive biosensors are presented in this paper. The biosensors consist of giant magnetoresistive (GMR) type multilayers. The magnetic beads labelled with different biological structures are assembled on top of the sensor element or between sensor elements. In both cases we used differential measurement setup in order to extract only the signal which corresponds to the field produced by the magnetic beads. The simulations were performed when the magnetic field is applied parallel and perpendicular to the easy axis of the GMR sensor. When the magnetic particles are located between two GMR sensors, placed in opposite branches of a Wheatstone bridge, sharp and symetric peaks will appear around zero field at which the GMR sensors present a maximum sensitivity.