Comparative study of the sensing performance of orthogonal fluxgate sensors with different amorphous sensing elements

A comparative study of the sensing performance of orthogonal fluxgate sensors using different amorphous wires as sensing elements is presented. The sensing elements used are Co-based amorphous wire with and without glass-coating. The results show that the sensor with amorphous wire sensing element made by cold draw is more sensitive when the excitation ac passing through the wire is of low frequency, and the sensor with glass-coated wire is more sensitive when the excitation ac is of high frequency. The results are explained by considering the magnetic properties of the wires, such as the magnetic softness of the wires, indicated by the hysteresis loops, as well as by the magneto-impedance (MI) effect ratios that tell the ac magnetic properties of the wires under the influence of “skin effect”. The MI spectrum results show that the MI ratio of the cold-draw amorphous wire is larger at low frequency and smaller at high frequency, compared to that of the glass-coated wire, which reveals that the circumferential permeability plays a key role in the sensor sensitivity and the skin effect is related to the frequency characteristics.