A new frequency modulated hybrid MEMS magnetometer: from design to fabrication

This thesis work was carried out at PoliFAB and deals with the design and the fabrication of a frequency-modulated magnetometer combining silicon MEMS and magnetic elements. The sensor constitutes a proof of concept device for the European FET Open project OXiNEMS (OXide NanoElectroMechanical Systems), which aims to realize a new generation of ultra-sensitive magnetometers integrating transition metal oxides M/NEMS and superconductive or ferromagnetic materials. These novel hybrid sensors are expected to overcome the limitations of the magnetometers employed nowadays in magnetoencephalographic (MEG) systems (e.g. SQUIDs), hence paving the way for novel diagnostic methods, such as the combined MEG/ULF-MRI (ultra-low field magnetic resonance imaging) technique. The first part of the thesis deals with a general study of the first OXiNEMS sensor manufactured at PoliFAB; it is proved that this technology is working correctly in detecting the presence of an external magnetic field. In the second part, it is discussed a new design for the sensor, improving the performances of the first run device. The design choices are presented and the expected performances are studied by means of an analytical model and micromagnetic simulations. Finally, after having described the optimization of the fabrication process, it is presented the realization and the characterization of the device, highlighting the agreement with analytical and numerical models.