A differential magnetometer for magnetic nanobeads characterization

In this paper we present a simple differential magnetometer that allow us to measure the stray magnetic field generated by superparamagnetic beads on which a magnetic field is applied. As sensors are used two magnetodiodes connected in a differential setup in order to increase the thermal stability and the magnetic sensitivity that can reach values between 0.2 to 0.7 mV/G. Because the magnetic field generated by the superparamagnetic beads has low values and the field needed to saturate them can reach even 500 Oe, a special setup is presented that allow us to separate these two fields inside the sensor.