Magnetic Field Sensor Using Asymmetric Giant Magnetoimpedance Effect Created by Micro Magnets

Abstract A magnetic field sensor was developed using asymmetric giant magnetoimpedance (AGMI) effect. Amorphous ferromagnetic (Fe0.06Co0.94) 72.5Si12.5B15 wires were used in this study. The 2 cm long wire showed about 88 % and the 7 cm long wire showed about 197 % giant magnetoimpedance effect. When two micro magnets were placed 1 cm away from the ends of the wire, a distortion in two peak shapes of the GMI curve was observed and asymmetry was created by micro magnets and 7 cm long wire showed about 148 % AGMI effect. A simple and a new approach was designed to develop a magnetic field sensor, in the design circuit two signal generators were used to arrange linearity and dc offset in the output signal. The circuit output showed good linearity and zero hysteresis at ±250 A/m and ± 50 A/m magnetic field regions for 2cm wires long and 7 cm wires long, respectively.