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

Abstract The magnetoresistance (MR) of different sensor setups of bilayer arrays by micromagnetic simulations has been studied in order to detect 20 nm diameter Fe 3 O 4 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.