Amorphous wire and CMOS IC based sensitive micro-magnetic sensors utilizing magneto-impedance (MI) and stress-impedance (SI) effects and applications

Abstract

Sensitive, quick response and low power consumption micro-magnetic sensors have been developed utilizing the magneto-impedance (MI) and stress-impedance (SI) effects in zero-magnetostrictive (zero-/spl lambda/) and negative-magnetostrictive amorphous wires connected with CMOSFET IC sensor circuits. The MI magnetic field sensor using zero-/spl lambda/ amorphous wires of 30 /spl mu/m diameter and 2 mm length represents the resolution of about 1 /spl mu/G for AC fields and about 100 /spl mu/G for the DC field with /spl plusmn/3 G in the full scale, the cut-off frequency of about 1 MHz, and low power consumption of about 10 mW for the CMOS MI sensor. The SI sensor using a 20 /spl mu/m diameter negative-/spl lambda/ amorphous wire shows the gauge factor of about 4000 for stress (strain) sensors and the resolution of 0.1 Gal for acceleration sensors. The principles, basic features, and applications of MI and SI sensors are summarized.