Magnetic Force Based Resonant Magnetic Field Sensor With Piezoelectric Readout

This paper presents the design, fabrication and testing of a prototype resonant magnetic field sensor utilizing piezoelectric excitation and detection with ferromagnetic film at the free end of micro-cantilever for magnetic field detection. The change in the resonant frequency of the beam due to the presence of an external magnetic field is measured using a sensing piezo at the fixed end of the beam. Customized process steps are followed with six masks to fabricate the micro resonant magnetic field sensor with Aluminum nitride as piezoelectric material and soft ferromagnetic material for magnetic field detection. The mechanical, electrical and magnetic characterizations are carried out to evaluate the performance of the sensor. Results from analytical and experimentation are in close agreement and are in the same dimensional range. Dispenser printed permanent magnets are also integrated and this is the first of its kind to enhance the magnetic property in micro resonant magnetic field sensors.