Optimizing the sensitivity of a GMR sensor for superparamagnetic nanoparticles detection: Micromagnetic simulation

The magnetoresistance (MR) of different sensor setups of bilayer arrays by micromagnetic simulations has been studied in order to detect 20 nm diameter Fe3O4 superparamagnetic nanoparticles. The MR signal of sensors with different sizes and/or different aspect ratios has been compared. We have proved that for a sensor with a given shape and size, the sensor sensitivity can be increased by raising the aspect ratio of its bilayers. The sensors can detect from hundreds down to a few tens of superparamagnetic nanoparticles randomly distributed on the sensor surface.