Sensitive micro magnetic sensor family utilizing magneto-impedance (MI) and stress-impedance (SI) effects for intelligent measurements and controls

Recent development in the field of highly sensitive, quick response and small power consumption micro magnetic sensor family (MI sensors and SI sensors) utilizing the magneto-impedance (MI) and stress-impedance (SI) effects mainly in amorphous wires is summarized. The MI and SI sensors are constituted with CMOS inverter IC and MI and SI heads magnetized with the sharp pulse current generating the skin effect, which realize the application specified integrated circuits (ASIC) sensors. Various pocketable or handy micro sensors have been developed, such as the handy terrestrial field sensor and the electronic compass for automobiles using the amorphous zero-magnetostrictive (FeCoSiB) wire MI chips combined with the CMOS IC circuit. Highly sensitive micro stress (strain) sensors and micro acceleration sensors are also developed using the amorphous magnetostrictive (CoSiB) wire SI elements combined with the CMOS IC circuit. Various small oscillatory motions in human bodies, such as the finger tip blood vessel pulsation (FTP) and the mechano-encephalogram, and road bridge oscillation during car passing are sensitively detected using the SI acceleration sensor. (C) 2001 Elsevier Science B.V. All rights reserved.