Self-biased giant magneto-impedance sensor probe and preparation method thereof

Abstract

A self-biased giant magneto-impedance sensor probe and a preparation method thereof belong to the technical field of information functional devices. The probe comprises an amorphous strap-shaped magnetic material and metal counter electrodes positioned at two ends of the surface of the amorphous strap-shaped magnetic material, wherein two vectolite films are respectively deposited on two sides of the amorphous strap-shaped magnetic material between the metal counter electrodes; and the upper and the lower vectolite films have consistent hard magnetic phase characteristic in the length direction of the amorphous strap-shaped magnetic material. During preparation of the probe, the key process is that the vectolite films are deposited on the amorphous strap-shaped magnetic material through the radio-frequency magnetron sputtering technology and are magnetized through a magnetizer to present hard magnetic phase. The self-biased giant magneto-impedance sensor probe provided by the invention has the characteristics of small size, easiness in integration and no extra power consumption; the product is simple to prepare, the process is controllable and the stability is high; and a wider linear working space can be obtained and the sensitivity is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of information function devices, and relates to a self-bias giant magneto-impedance sensor probe and a preparation method thereof. Background technique [0002] Since 1994, the study of the giant magnetoimpedance effect has attracted extensive attention of scientists from all over the world because of its great application prospects in the field of magnetic sensors and information storage. Early research focused on both theoretical and experimental studies of the magnetic field and frequency characteristics of the impedance of various components and material forms (wires, ribbons, and films) under different process conditions. Research in this area has made important progress. In order to make the giant magnetoimpedance effect more practical, the current research focuses on how to improve the impedance change rate and sensitivity of the giant magnetoimpedance sensor. [0003] Although compared with filamen...

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Problems solved by technology

The asymmetric giant magneto-impedance effect of filamentary or strip-shaped materials can be realized by the following methods: 1) Bias coil method: by preparing a coil on the sensor, passing a current in the coil to generate a bias magnetic field, if the two along The giant magneto-impedance probes biased in opposite directions are connected in a differential form, and a linear output near zero field can be achieved; however, the method of using an additional coil to generate a bias field will not only increase the difficulty and cost of the sensor unit’s preparation, but more importantly, The fact that adding current to generate a bias field will significantly increase the power consumption of the probe, which is undesirable when the sensor is applied

2) Permanent magnetic bias method: similar to method 1), but using a permanent magnet instead of a bias coil, although this does not increase the power consumption of the sensor, it will increase the volume of the sensor, which is not conducive to the miniaturization of the sensor

Since this asymmetric characteristic is formed due to exchange coupling, the power consumption is greatly reduced compared to method 1), and the volume is also greatly reduced compared to method 2), but due to this hard magnetic / soft magnetic exchange coupling field Formed by annealing, the amorphous magnetic material is easily oxidized when exposed to air, which will reduce the working stability of the prepared sensor probe over time, and more importantly, the thickness of the hard magnetic layer produced by this annealing method is limited ( About 100 nanometers), which makes the hard / soft magnetic exchange coupling field small, and its zero-field linear working area is small (less than ±2Oe), and the sensitivity is insufficient

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