Off-diagonal GMI sensor with stress-annealed amorphous ribbon

A novel type of magnetic field sensing device using a single amorphous ribbon is presented. The sensor operation is based on a non-vanishing off-diagonal magnetoimpedance in ribbons with creep-induced anisotropy when the ribbon is driven by high frequency current with a dc component. The sensor was examined in two regimes. First, it was operated by laboratory instruments in the open loop connection. Afterwards, simple electronics was developed to operate the sensor in the closed feedback loop. Noise RMS value of 210 pT and 410 pT in 10 Hz band and noise spectral density of 17 pT√Hz at 1 Hz and 70 pT√Hz at 1 Hz were achieved when sensor operated in open and closed feedback loop, respectively. Temperature offset drift of −67 nT/K and linearity error 0.2% FSR in the range ±75 μT were achieved in the feedback loop connection.