HIGH SENSITIVITY TRIAXIAL MAGNETIC FIELD TRANSDUCER, BASED ON THE PHASE CHARACTERISTICS OF THE GMI EFFECT

The Laboratory of Biometrology of PUC-Rio has been developing magnetic field transducers to be used in biomedical applications. Investigations recently accomplished indicate the possibility of a new research line, which considers the changes in the phase characteristics of Giant Magnetoimpedance (GMI) sensors due to varying low-intensity magnetic fields. In spite of being less explored in the literature, the work carried out so far indicates that the sensitivity of the phase can lead to more promising results than the ones already obtained with transducers based on the variation of the impedance magnitude. This manuscript discusses the development process of a new class of magnetic field transducers, beginning with the definition of the ideal stimulation condition for the sensor elements, proceeding to discuss the configuration that makes possible a triaxial measurement and closing with the electronic circuit that conditions the GMI ribbons and reads their phase variation as a function of an axial magnetic field. Simulation studies of a complete transducer, including the conditioning circuit and based on data obtained from measured curves, have shown that an improvement in sensitivity greater than 20 times can be expected when compared to the previous magnitude-based transducers.