Highly sensitive magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire

Abstract

The design and performance of a magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire are presented. The sensing element of the magnetometer is a 10‐mm long piece of Co–Fe–Ni–B–Si–Mo microwire with a small pick‐up coil of 85 turns wounded around the microwire. The electronics with a feedback circuit is used to register an electromotive force proportional to the external magnetic field applied along the wire axis. In the absence of the feedback current the magnetometer is capable of measuring a narrow range of magnetic fields, ±3.5 μT, in the frequency range of 0–1 kHz, the level of the equivalent magnetic noise being about 10 pT Hz−1/2 at a frequency of 300 Hz. The use of the feedback circuit increases the range of the measured magnetic fields up to ±250 μT. Photo of the giant magnetoimpedance magnetometer based on the off‐diagonal GMI effect in Co‐rich glass‐coated microwire.

Highly Sensitive CMOS Magnetoimpedance Sensor Using Miniature Multi-Core Head Based on Amorphous Wire

“…Pick-up coils placed on a-wire are applicable for signal detection in MI sensors [1], [3], [5], [6]. A sensitivity dependence on number of turns N of pick-up coils have been investigated for a-wire with 30 μm in diameter [3].…”

“…A miniature head with a pick-up coil of several hundred turns is required to realize highly sensitive MI IC with picotesla resolution. Use of pick-up coil has an advantage to realize of highperformance linear magnetic field sensor [5], [6] is applicable in wide fields. There have been several reports about nonlinear MI sensors, which show extremely large impedance change with applying magnetic field [7], [8].…”

Engineering of Magnetic Properties of Magnetic Microwires

“…The main interest in GMI effect is related to one of the largest magnetic field sensitivities (up to 10 %/A/m) among non-cryogenic effects making it quite interesting for application in magnetic sensors and magnetometers [9][10][11][12].…”

Development of precise off-diagonal magnetoimpedance gradiometer for magnetocardiography

“…3,4 Furthermore, arrays of flexible GMI sensors have been developed to measure magnetic brain signals. 5 Compared with other sensors used for MCG measurements, the MI sensor has the advantage of being compact and easy to handle.…”