Vibrational sensor based on Giant Magnetoimpedance effect

The main purpose of this work is to explore the use of the Giant Magneto Impedance effect (GMI) in a sensor to detect low frequency vibrations of moving objects. This effect is characterized by huge variations of the high frequency electric impedance of a soft magnetic conductor under the action of an external magnetic field. Thus, the detection principle is based on the characterisation of the magnetic field generated by a permanent magnet attached to the object under movement (vibration). Before analysing the configuration of the sensor, it was necessary to study different materials to be employed as sensor nucleus. This previous characterization enabled to select the material with optimum response (maximum impedance variation) and to determine the optimum operation conditions. These two main parameters which were studied are: frequency and current. In order to obtain the best sensor’s response, it must be powered with the optimum values of frequency and current. Once the optimum parameters of the exciting frequency were determined, the response of the sensor was studied for several vibration frequencies and under certain conditions.