Magnetic field sensor using the asymmetric giant magnetoimpedance effect created by micromagnets

A magnetic field sensor was developed using the asymmetric giant magnetoimpedance (AGMI) effect. Amorphous ferromagnetic (Fe 0.06 Co 0.94 ) 72.5 Si 12.5 B 15 wires were used in this study. The 2-cm-long wire showed an approximately 88% giant magnetoimpedance effect, and the 7-cm-long wire showed an approximately 197% giant magnetoimpedance effect. When two micromagnets were placed 1 cm from the ends of the wire, a distortion in the two peak shapes of the GMI curve was observed, and asymmetry was created by the micromagnets. The 7-cm-long wire showed an approximately 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 the linearity and dc offset in the output signal. The circuit output showed good linearity and zero hysteresis in the ± 250 A/m and ± 50 A/m magnetic field regions for the 2-cm-long and 7-cm-long wires, respectively.