Magnetic Microwires With Field-Induced Helical Anisotropy for Coil-Less Fluxgate

Abstract

We present a new method for production of magnetic microwire with helical anisotropy. Coil-less fluxgate sensors are generally composed of a bimetallic wire excited by an alternating current; in order for the wire to work in coil-less fluxgate mode, the magnetic layer of the wire needs to have helical anisotropy. So far, we have achieved such anisotropy by mechanically twisting the wire. However, this method has some disadvantages for practical applications, mainly regarding the sensor stability. We propose a method that provides helical anisotropy by applying a helical field during the electrodeposition: this is achieved by the superposition of a longitudinal field generated by a Helmholtz coil and a circumferential field produced by a direct current flowing through the core of the wire during electrodeposition.

On the state‐of‐the‐art in magnetic microwires and expected trends for scientific and technological studies

“…8). Recently, optimization of the magnetic response has been achieved by the use of bimetallic magnetic microwires with suitable helical magnetic anisotropy by adequate fabrication processing under helical magnetic field 73. Previously, this family of multilayer microwires has been proposed as sensing elements in multifunctional device for temperature and stress (tensile, bending) sensor based on modified small‐angle magnetization rotation process 74.…”

Orthogonal Fluxgates

“…This was later confirmed by observing coil-less fluxgate effect also on magnetic wires manufactured with built-in helical anisotropy. In (Butta et al, 2010b) a Permalloy layer is electroplated under the effect of a helical field, obtained as a combination of a longitudinal field imposed with a Helmholtz coil and a circular field generated by a dc current flowing in the wire. In (Atalay et al, 2011;Butta et al, 2010c; I wire V wire www.intechopen.com…”

Optimization Design and Characterization of Helmholtz Coils

“…Helmholtz coil design is simple and there are many commercially available designs for all kinds of applications. In order to examine the magnetic field sensing of a fluxgate sensor, a large area with uniform magnetic field is required (Butta et al, 2010). The advantage of having a large area is that it will allow easy access of the sensor during measurement (Butta et al, 2010).…”

“…In order to examine the magnetic field sensing of a fluxgate sensor, a large area with uniform magnetic field is required (Butta et al, 2010). The advantage of having a large area is that it will allow easy access of the sensor during measurement (Butta et al, 2010). A laboratory design and characterization of Helmholtz coils is a better choice when Helmholtz coil with larger areas that are available in the market are very expensive.…”