On magnetic nanoparticles detection using planar Hall effect sensors

In this paper we present aspects concerning magnetic nanoparticles detection using a planar Hall effect magnetometer, disk-shaped of 1mm diameter, build from a single Permalloy layer, 20 nm thick, deposited on oxidized Si substrate. This device allows us to measure the stray magnetic field generated by superparamagnetic beads which are magnetized by an external field. During the experiments we found strong sensor signal dependence, both in shape and magnitude, with the particles at different positions. The results are explained by means of micromagnetic simulations were magnetostatic interactions between magnetic nanobeads and sensor are clearly highlighted.