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Flexible electronic devices extended abilities of humans to perceive their environment conveniently and comfortably. Among them, flexible magnetic field sensors are crucial to detect changes in the external magnetic field. State‐of‐the‐art flexible magnetoelectronics do not exhibit low detection limit and large working range simultaneously, which limits their application potential. Herein, a flexible magnetic field sensor possessing a low detection limit of 22 nT and wide sensing range from 22 nT up to 400 mT is reported. With the detection range of seven orders of magnitude in magnetic field sensor constitutes at least one order of magnitude improvement over current flexible magnetic field sensor technologies. The sensor is designed as a cantilever beam structure accommodating a flexible permanent magnetic composite and an amorphous magnetic wire enabling sensitivity to low magnetic fields. To detect high fields, the anisotropy of the giant magnetoimpedance effect of amorphous magnetic wires to the magnetic field direction is explored. Benefiting from mechanical flexibility of sensor and its broad detection range, its application potential for smart wearables targeting geomagnetic navigation, touchless interactivity, rehabilitation appliances, and safety interfaces providing warnings of exposure to high magnetic fields are explored. [ABSTRACT FROM AUTHOR]

Periodontitis, characterized by inflammation and loss of periodontal tissue, is a significant health complication for individuals with diabetes mellitus (DM). Buildup of advanced glycation end-products (AGEs) in DM poses an increased risk of periodontitis via inflammaging. Ganoderma immunomodulatory protein (GMI) shows promise in suppressing inflammaging by mitigating oxidative stress and inflammation via Nrf2 modulation. However, its specific protective effects are not fully understood. Thus, this study aimed to investigate GMI's anti-inflammaging properties and its underlying mechanism in diabetic-associated periodontitis (DP). We first simulated DP by culturing human gingival fibroblasts (HGFs) with AGEs and lipopolysaccharides from P. gingivalis (LPS). We then evaluated the impact of GMI on cell proliferation, migration and wound healing. Additionally, we assessed GMI's effects on the components of inflammaging such as reactive oxygen species (ROS) formation, cellular senescence expression, IL-6 and IL-8 secretions, and NF-κB phosphorylation. Next, we explored whether GMI's anti-inflammaging effects are mediated through the Nrf2 pathway by evaluating Nrf2 and HO-1, followed by the assessment of IL-6 and IL-8 post-Nrf2 knockdown. Our findings revealed that GMI treatment suppressed ROS production, cell senescence, IL-6 and IL-8 and NF-κB phosphorylation. Furthermore, GMI upregulated Nrf2/HO-1 expression and its protective effects were reversed when Nrf2 was knocked down. In conclusion, GMI exerts its anti-inflammaging effect via the modulation of the Nrf2/NF-κB signaling axis in DP in vitro, highlighting its potential as an effective adjunct treatment for diabetes-related periodontitis. [ABSTRACT FROM AUTHOR]

Purpose: Microribbon with meander type based on giant magnetoimpedance (GMI) effect has become a research hot spot due to their higher sensitivity and spatial resolution. The purpose of this paper is to further optimize the line spacing to improve the performance of meanders for sensor application. Design/methodology/approach: The model of GMI effect of microribbon with meander type is established. The effect of line spacing (Ls) on GMI behavior in meanders is analyzed systematically. Findings: Comparison of theory and experiment indicates that decreasing the line spacing increases the negative mutual inductance and a consequent increase in the GMI effect. The maximum value of the GMI ratio increases from 69% to 91.8% (simulation results) and 16.9% to 51.4% (experimental results) when the line spacing is reduced from 400 to 50 µm. The contribution of line spacing versus line width to the GMI ratio of microribbon with meander type was contrasted. This behavior of the GMI ratio is dominated by the overall negative contribution of the mutual inductance. Originality/value: This paper explores the effect of line spacing on the GMI ratio of meander type by comparing the simulation results with the experimental results. The superior line spacing is found in the identical sensing area. The findings will contribute to the design of high-performance micropatterned ribbon with meander-type GMI sensors and the establishment of a ribbon-based magnetic-sensitive biosensing system. [ABSTRACT FROM AUTHOR]

The magnetoimpedance effect allows us to estimate the extent of spin dependent scattering in disordered solids. The change in impedance with respect to applied magnetic field manifests through local change in permeability on the surface and it amplifies at defect sites. The local electrical inhomogeneities are expected to aid this effect through spin dependent scattering. The organic conjugated electrical networks provide scope for producing such inhomogeneities formed by path defects and protonic charge accumulation leading to spin dependent scattering. This hypothesis is investigated in the present work taking polyaniline as a prototype network. The electrical inhomogeneities in the network were controlled by selective oxidation and aging in polyaniline. The Giant Magnetoimpedance (GMI) was observed in the electrically inhomogeneous network with the change in electrical impedance of the order of 50%–60% for lower frequencies with prominent capacitive coupling and a change of the order of 200% at higher frequencies with prominent inductive coupling with the application of magnetic field. However, no spin accumulation was observed in the insulating networks formed by a modified oxidative process. This study is expected to serve as a tool to develop frequency selective spin accumulation based magnetic field sensors and oscillator networks. [ABSTRACT FROM AUTHOR]

Magnetic microwires with amorphous structures can present a unique combination of excellent magnetic softness and giant magnetoimpedance (GMI) effects together with reduced dimensions and good mechanical properties. Such unique properties make them suitable for various technological applications. The high GMI effect, observed in as-prepared Co-rich microwires, can be further optimized by postprocessing. However, unexpected magnetic hardening and a transformation of the linear hysteresis loop into a rectangular loop with a coercivity on the order of 90 A/m were observed in several Co-rich microwires upon conventional annealing. Several routes to improve magnetic softness and GMI effect in Fe- and Co-rich magnetic microwires are provided. We observed that stress annealing could remarkably improve the magnetic softness and GMI ratio of Co-rich microwires. Thus, almost unhysteretic loops with a coercivity of 2 A/m and a magnetic anisotropy field of about 70 A/m are achieved in Co-rich microwires stress annealed at appropriate conditions. The observed change in hysteresis loops and the GMI effect is explained by stress-annealing-induced anisotropy, which is affected by the stresses applied during annealing and by the annealing temperature. While as-prepared Fe-rich amorphous microwires present a low GMI effect, appropriate postprocessing (annealing and stress annealing) allows for a remarkable GMI ratio improvement (an order of magnitude). The evaluated dependence of the maximum GMI ratio on frequency allows the identification of the optimal frequency band for the studied samples. The origin of stress-annealing-induced anisotropy and related changes in hysteresis loops and the GMI effect are discussed in terms of the relaxation of internal stresses, "back-stresses", as well as structural anisotropy. [ABSTRACT FROM AUTHOR]

We studied the temperature dependence of the magnetic properties and giant magnetoimpedance, GMI, effect in as-prepared and annealed Co69.2Fe3.6Ni1B12.5Si11Mo1.5C1.2 glass-coated microwires with nearly-zero magnetostriction. Substantial changes in the GMI ratio, ΔZ/Z, value and magnetic field, H, dependence, and in the hysteresis loops upon heating were observed. The modification in the hysteresis loop shape upon heating correlates with a change in the ΔZ/Z (H) dependencies. In as-prepared and most of the heat treated samples the hysteresis loop transformation from inclined to squared upon heating correlates with the change in ΔZ/Z(H) dependencies from double-peak to single-peak. However, the stress-annealed at 118 MPa samples present better thermal stability of the ΔZ/Z(H) dependencies and hysteresis loops. In all the studied samples an increase in the GMI ratio at 300 °C was observed. The origin of the observed temperature dependences is discussed in terms of the Hopkinson effect, temperature dependence and relaxation of internal stresses, induced magnetic anisotropy, and temperature dependence of the magnetostriction coefficient.

The giant magnetoimpedance (GMI) effect can be used to precisely investigate the magnetization process of samples. However, it is influenced by the magnetic interactions between the samples, among which dipolar interaction is a crucial factor to tune the GMI response and further design in magnetic device. Therefore, it is essential to study the impact of dipolar interaction on the GMI effect. Previous research was limited at the qualitative analysis. The introduction of the geometric factor between the strips and the application of the minimization of the free energy allowed for a quantitative analysis of their influence. Theoretical predictions and experimental results indicated that dipolar interaction led to an inward shift of the double peaks in the impedance curve and an increase in the maximum GMI ratio. This study enabled more accurate and precise analysis of the influence of dipolar interaction in both strip-shaped and filamentous-shaped magnetic samples on magnetic characterization. Thus, the GMI curve could expand our understanding of the internal interactions within magnetic materials and offer perspectives for the design and optimization of magnetic materials in practical applications. [ABSTRACT FROM AUTHOR]

A sensitive non-contact sensing system based on the CoFeNiSiB amorphous ribbon giant magnetoimpedance (GMI) effect is proposed for current testing. The sensing system consists of a GMI probe, a sinusoidal current generator, a voltage follower, a preamplifier, a low-pass filter, and a peak detector. Four different GMI probes derived from amorphous ribbon meanders are designed and fabricated through MEMS processes. GMI probes were driven by a 10 MHz, 5 mA AC current. A permanent magnet was used to provide a bias magnetic field for the probe. The effect of the bias magnetic field on the output DC voltage was investigated. This non-contact current sensing system exhibits good sensitivity and linearity at a bias magnetic field Hbias = 15 Oe. The sensitivity can reach up to 24.2 mV/A in the ±1.5 A range. [ABSTRACT FROM AUTHOR]

Longitudinal giant magnetoimpedance effect of [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element was investigated depends on stray magnetic field of epoxy magnetic composite with 30% weight concentration of iron oxide magnetic microparticles. Configuration of an experiment was a model of thrombus detection in a blood vessel. Stray magnetic field was varied by movement of a magnetic composite above the element perpendicular to the long side. Composite was either magnetized or not to the state of remanence. As the magnetic composite approaches the GMI element, MI ratio curves are smoothed and shifted along the field axis and maximum value of the MI ratio decreases. Magnetic properties of magnetic composite and film element were investigated as well. [ABSTRACT FROM AUTHOR]

The dipolar interactions were investigated through the giant magnetoimpedance effect in FINEMET/IGZO/CoFeSiB composite ribbons. The interface between the CoFeSiB film and FINEMET ribbon was separated by IGZO layer in FINEMET/IGZO/CoFeSiB composite ribbons, which effectively induced dipolar interactions. The dipolar interactions were analyzed by the peak position field (Hp) of giant magnetoimpedance effect and magnetic properties. The results show that the Hp decreased with the increase of the IGZO layer thickness. These results suggest that the GMI ratio (58%) and characteristic frequency (800 kHz) were optimized. The composite ribbons have high GMI ratio and low frequency, which can be applied in magnetic field sensors. [ABSTRACT FROM AUTHOR]

As-prepared Fe-rich microwires with perfectly rectangular hysteresis loops present magnetization reversal through fast domain wall propagation, while the giant magnetoimpedance (GMI) effect in Fe-rich microwires is rather low. However, the lower cost of Fe-rich microwires makes them attractive for magnetic sensors applications. We studied the effect of conventional (furnace) annealing and Joule heating on magnetic-propertied domain wall (DW) dynamics and the GMI effect in two Fe microwires with different geometries. We observed that magnetic softness, GMI effect and domain wall (DW) dynamics can be substantially improved by appropriate annealing. Observed experimental results are discussed considering the counterbalance between the internal stresses relaxation and induced magnetic anisotropy associated with the presence of an Oersted magnetic field during Joule heating. [ABSTRACT FROM AUTHOR]

Co-based rapidly quenched amorphous ribbons are soft ferromagnets with well-adjustable functional properties. Their effective magnetic anisotropy and magnetization processes depend on the preparation conditions and geometrical parameters. It was found that giant magnetoimpedance effect (MI) for the FeCoCrSiB ribbons without heat treatments after relaxation annealing and after stress annealing at 350∘C shows critical dependence on the value of the demagnetizing factor. The range of FeCoCrSiB ribbons lengths with a significant change in properties is considered in a comparative analysis of the experimental results and model calculations. Quantitative analysis of the contribution of the demagnetizing fields and surface magnetic charges are discussed as the main mechanism for reducing the GMI properties of amorphous ribbons. These data are important for the development of the ribbon-based devices for practical applications of microelectronics. [ABSTRACT FROM AUTHOR]

The giant magnetoimpedance effect of multilayered thin films under stress has great application prospects in magnetic sensing, but related studies are rarely reported. Therefore, the giant magnetoimpedance effects in multilayered thin film meanders under different stresses were thoroughly investigated. Firstly, multilayered FeNi/Cu/FeNi thin film meanders with the same thickness were manufactured on polyimide (PI) and polyester (PET) substrates by DC magnetron sputtering and MEMS technology. The characterization of meanders was analyzed by SEM, AFM, XRD, and VSM. The results show that multilayered thin film meanders on flexible substrates also have the advantages of good density, high crystallinity, and excellent soft magnetic properties. Then, we observed the giant magnetoimpedance effect under tensile and compressive stresses. The results show that the application of longitudinal compressive stress increases the transverse anisotropy and enhances the GMI effect of multilayered thin film meanders, while the application of longitudinal tensile stress yields the opposite result. The results provide novel solutions for the fabrication of more stable and flexible giant magnetoimpedance sensors, as well as for the development of stress sensors. [ABSTRACT FROM AUTHOR]

Giant magnetoimpedance, GMI, effect and magnetic properties upon temperature influence of as-prepared and stress-annealed amorphous Fe75B9Si12C4 glass-coated microwires produced by the Taylor-Ulitovsky technique are analyzed. Remarkable change in the hysteresis loops and GMI effect is observed for both samples upon heating. Tuning of the stress-annealing conditions allows one to vary the temperature dependence. Furthermore, it is observed almost complete reversibility of the changes induced by the temperature. Observed dependences are explained by the heating effect on the internal stresses relaxation, by the modification of the thermal expansion coefficients of the metallic nucleus and the glass coating, and by the Hopkinson effect. [ABSTRACT FROM AUTHOR]

The giant magneto-impedance (GMI) effect of Co83.2Fe5.2Si8.8B2.8 ribbons at frequencies of <1 MHz was analyzed. To improve the GMI response, a Joule annealing treatment was conducted with a direct current, and the domain structure of the ribbon surface was investigated via magneto-optical Kerr effect microscopy. The annealed ribbons show larger impedance changes under external magnetic fields, and higher field sensitivity is obtained by certain current annealing treatments. The field sensitivity of 418 and 782%/(kA/m) at 0.2 MHz and 0.8 MHz are achieved after annealing at 0.8 A for 20 min. The annealing treatment under direct electric current induces stress relaxation, and domain rearrangement, and the crystallization process gradually increases with the increasing current density, which gives rise to anisotropic reformation. The release of stresses due to Joule heating below the crystallization temperature causes the homogenous distribution of stress induced by rapid solidification and influences the elastic anisotropy, causing the domain structures to become much more regular. The crystallization, along with the precipitation of hard magnetic phases, increases the crystal anisotropy and induces the intense magnetic coupling action. Consequently, the magnetic domains in the annealed ribbons are rearranged with reformed anisotropy by Joule annealing heat and by the transverse magnetic field induced by the current. The irregular domains, with complex anisotropy in the as-cast ribbons corresponding to the weak GMI response, are transformed into regular and strip-like domains, with transverse easy magnetization after annealing at 0.4 A. After annealing at 0.8 A, the domains are further transformed into fine axial fingerprint-like domains, which are much more sensitive to the change in the axial external magnetic field, allowing for the best GMI response. These results indicate that the Joule annealing treatment is an optional method to optimize the soft magnetic properties and the GMI effect of these Co-rich ribbons at low frequencies. [ABSTRACT FROM AUTHOR]

Due to the sensitive magnetic field response of the GMI effect, the peak field in magneto impedance curves obtained from the composite magnetic ribbons shows great dependence on the magnetic interaction, which has gained intensive attention in the study of the diversity and the mechanism of magnetic interaction. In this work, FINEMET/Fe 20 Ni 80 /SiO 2 /Fe 20 Ni 80 composite ribbons with a fixed thickness of outer Fe 20 Ni 80 layer (200 nm) and variable thickness ratio of the inner Fe 20 Ni 80 and SiO 2 layers, ranging from the 1:4 to 4:1 were prepared. Then the GMI response was utilized to investigate the influence of the exchange couple and the dipole interaction to magnetic properties of the base ribbon. The experimental results indicated that additional SiO 2 layer can successfully induce slight magnetic differences of the two Fe 20 Ni 80 layers, which results in the emergence of four-peak GMI profiles. Besides, the frequency-dependent nature of the peaks was explored, revealing that both dipole interaction and exchange couple influence the magnetic properties, contributing to the occurrence of four-peak GMI curves. Thus, the insights presented in this work are thought to be valuable for understanding the mechanisms of multilayer composite ribbons in future sensing applications. [ABSTRACT FROM AUTHOR]

We studied the effect of annealing on the hysteresis loops and the Giant magnetoimpedance, GMI, ratio of Co 72 Fe 4 B 13 Si 11 glass-coated microwire. A remarkable GMI ratio improvement up to 735 % is observed after annealing at appropriate conditions. Observed magnetic softening and GMI ratio improvement have been discussed considering the internal stresses relaxation. The observed change in the hysteresis loop shape and in GMI ratio upon annealing correlate with a change in the magnetostriction coefficient sign and values with increasing of annealing temperature. [Display omitted] • Substantial improvement of GMI ratio up to 735 % in Co 72 Fe 4 B 13 Si 11 glass-coated microwires after annealing. • Change in the hysteresis loop shape in Co 72 Fe 4 B 13 Si 11 glass-coated microwires upon annealing. • Gradual increase in the magnetostriction coefficient values with increasing of annealing temperature. • Change in sign of the magnetostriction coefficient from negative to positive upon annealing. [ABSTRACT FROM AUTHOR]

In this paper, the giant magneto-impedance (GMI) model of a cylindrical alloy fiber was established by the Maxwell equation and Landau–Lifshitz equation to simulate the influence of physical parameters of cylindrical alloy fiber on GMI under different control parameters. MATLAB was employed to calculate the magneto-impedance of cylindrical fibers and draw its curves. We found that when the anisotropic equivalent field of the fiber changes from 10Oe to 50Oe, the peak position of the GMI ratio also moves from about 10Oe to 50Oe, and the peak value gradually increases from 100% to 300%. The GMI ratio increased rapidly with the decrease in the magnetization damping coefficient. Our findings could further guide the design of supersensitive micro GMI sensors by optimally regulating the magnetic damping coefficient, the angle between the external magnetic field and easy axis and the anisotropic equivalent field of cylindrical alloy fibers. [ABSTRACT FROM AUTHOR]

The influence of a ferromagnetic cover layer on giant magnetoimpedance (GMI) effect in nearly-zero magnetostrictive Co66.5Fe3.5Si12.0B18.0 amorphous ribbon after being surface coated by an electrodeposited Co layer of 10 μm in thickness, has been studied in the high frequency range between 10 MHz and 1.5 GHz. Longitudinal MOKE measurements performed on both kind of samples reveal the influence of exchange coupling interaction at the interface between the magnetic amorphous ribbon and electrodeposited Co coating layer, which is sensitive to the skin depth effect at high ac current frequency values. Comparison between GMI responses of the Co coated amorphous ribbon and the as-cast sample is provided. A more sharp and well defined double-peaks dependence of impedance on magnetic field, but with lower peaks intensity, is observed for the Co coated ribbon in the frequency range of 10–100 MHz, while the peaks intensity is higher than that observed in the as-cast ribbon at the high frequency value of 1 GHz due to the higher resistance of the Co electroplated layer than the core one. The influence of a dc bias drive current on the GMI response in both amorphous ribbons (as-cast and Co layered) is analyzed, which originates the removal of magnetic domain structure from both, the as-cast and Co-coated ribbons, giving rise more sensitive GMI effect. CoFeSiB amorphous ribbon with vanishing magnetostriction can achieve improved high frequency magnetic properties after being surface coated with electrodeposited ferromagnetic layers, as outstanding candidates for electromagnetic and magnetomechanical engineering applications.

The giant magneto-impedance (GMI) effect of Co-based ribbons treated by using electrochemical polishing method has been investigated. The initial susceptibility (χi) and the longitudinal GMI ratio (L-GMI) as a function of the polishing time (t poli) were measured and discussed. The L-GMI firstly increases and then decreases with the increasing of t poli. At t poli = 30 s, the maximum GMI of ∼270% is obtained. This L-GMI trend as a function of t poli is mainly attributed to the variation of effective magnetic anisotropy (H k,eff). The variation of H k,eff comes from the optimization of surface qualities as well as the thinning of the thickness. The thinning of the Co-based ribbons results in the changing of demagnetization effect and, more importantly, the variation in the residual stress distributions. The latter effect will strongly affect the magnetization conditions for the samples with longer t poli: stress variation here is dominant over the influence of surface qualities in the final GMI effect. Furthermore, another factor that may influence GMI is the current density variation related to thickness decrease. At the same time, reducing of stray fields, closely related to surface qualities, is the dominant factor affecting GMI for the samples with shorter t poli. [ABSTRACT FROM AUTHOR]

Giant magnetoimpedance (GMI) effect in electrodeposited NiFeCo/Cu wire is studied in the intermediate frequency region (10 kHz–10 MHz) for various orientations of applied magnetic field (θ) with respect to the axis of plated wire. The experimental results show that the direction of the applied magnetic field has a significant impact on the GMI response of soft magnetic wires. The GMI ratio decreases as θ increases from 0 ∘ to 80 ∘ . At higher excitation frequencies, the magnetoimpedance vs. field curve exhibits a double peak at field H m whose value increases with θ . These experimental results are rigorously explained by the proposed model of circumferential permeability, based on the domain wall motion and magnetization rotation. Magnetic anisotropy dispersion, an important parameter that impacts the sensitivity of sensors based on GMI effect at high frequencies, is adequately considered. The circumferential permeability is reconstructed by fitting the experimental data of impedance on the proposed model of permeability. The shifting of peak field H m towards higher side as well as broadening of double peak with increasing inclination angle of external magnetic field with respect to wire axis is quite interesting. This feature can be utilized in development of directional magnetic sensors. [ABSTRACT FROM AUTHOR]

A small DC magnetic field can induce an enormous response in the impedance of a soft magnetic conductor in various forms of wire, ribbon, and thin film. Also known as the giant magnetoimpedance (GMI) effect, this phenomenon forms the basis for the development of high-performance magnetic biosensors with magnetic field sensitivity down to the picoTesla regime at room temperature. Over the past decade, some state-of-the-art prototypes have become available for trial tests due to continuous efforts to improve the sensitivity of GMI biosensors for the ultrasensitive detection of biological entities and biomagnetic field detection of human activities through the use of magnetic nanoparticles as biomarkers. In this review, we highlight recent advances in the development of GMI biosensors and review medical devices for applications in biomedical diagnostics and healthcare monitoring, including real-time monitoring of respiratory motion in COVID-19 patients at various stages. We also discuss exciting research opportunities and existing challenges that will stimulate further study into ultrasensitive magnetic biosensors and healthcare monitors based on the GMI effect. [ABSTRACT FROM AUTHOR]

In this work, a sensitive tool to detect magnetic nanoparticles (Fe3O4) based on a non-linear Giant Magnetoimpedance (GMI) effect is presented. The GMI sensor is designed with four nearly zero magnetostrictive ribbons connected in series and was analysed as a function of a constant external magnetic field and exciting frequency. The influence of the magnetic nanoparticles deposited on the ribbon surface was characterized using the first (fundamental) and second (non-linear) harmonics of the magnetoinductive voltage. The results show a clear enhancement of the sensor response in the high magnetic field region (H=1.5 kA/m) as a consequence of the stray field generated by the magnetic nanoparticles on the GMI ribbons' surface. The highest sensitivity ratios are obtained for the non-linear component in comparison with the fundamental response. The results open a new research strategy in magnetic nanoparticle detection. [ABSTRACT FROM AUTHOR]

The giant magnetoimpedance effect of multilayered thin films under stress has great application prospects in magnetic sensing, but related studies are rarely reported. Therefore, the giant magnetoimpedance effects in multilayered thin film meanders under different stresses were thoroughly investigated. Firstly, multilayered FeNi/Cu/FeNi thin film meanders with the same thickness were manufactured on polyimide (PI) and polyester (PET) substrates by DC magnetron sputtering and MEMS technology. The characterization of meanders was analyzed by SEM, AFM, XRD, and VSM. The results show that multilayered thin film meanders on flexible substrates also have the advantages of good density, high crystallinity, and excellent soft magnetic properties. Then, we observed the giant magnetoimpedance effect under tensile and compressive stresses. The results show that the application of longitudinal compressive stress increases the transverse anisotropy and enhances the GMI effect of multilayered thin film meanders, while the application of longitudinal tensile stress yields the opposite result. The results provide novel solutions for the fabrication of more stable and flexible giant magnetoimpedance sensors, as well as for the development of stress sensors.

This Part 3 focuses on the detailed study of the nanostructures forming in amorphous microwires which were previously received and described in the Part 2. The clustering process was studied at long-term DC Joule heating's much lower the crystallization temperature. Particular attention is paid to the study of the redistribution of the components of the initial stage of crystallization. The studies were carried out using the Atom Probe Tomography method (APT), which allows for the identification of individually considered atoms. A description and analysis of APT data processing techniques are provided for studying the cluster structure and distribution of elements in the amorphous matrix and crystalline phases. To identify crystalline phases, data obtained using High-Resolution Transmission Electron Microscopy (HR-TEM) and Scanning Transmission Electron Microscopy (STEM), as well as X-Ray Powder Diffraction (XRPD) with synchrotron radiation source were used. The applied techniques made it possible to establish that the formation of nuclei of crystalline phases is preceded by three stages of the amorphous microwire matrix evolution. At the first stage, clusters of the first and second coordination spheres appear. At the second stage, the clusters coagulate and become more than 2 nm in diameter, the stage ends with the predominance of Co-rich and silicide Me-Si clusters. At the third stage, they grow to an average diameter of 4.5 nm, the predominance of clusters of this type remains, and the formation of nuclei of crystalline phases α-Co and Co 2 Si, with a size of about 8 nm, occurs. This stage is characterized by high stable soft magnetic properties. With a further increase in the heat treatment temperature, a gradual deterioration of the soft magnetic properties and further structural transformation occur – structures of joint crystalline phases from two crystalline phases α-Co and Co 2 Si are formed in the amorphous matrix, and crystallization occurs with the alternation of these two phases. This leads to a significant redistribution of alloy components. As a result, an amorphous barrier layer is formed in the amorphous matrix near the surface of the growing two-phase substructures, enriched in chromium and silicon; this layer affects the growth of crystalline phases, slowing it down. • The effect of the DC Joule heating on the amorphous state evolution is shown. • Clusters and nuclei of crystalline phases using Atom Probe Tomography method were investigated. • The formation of nuclei of crystalline phases is preceded by three stages of the amorphous microwire matrix evolution. • The influence of chromium on the processes of clustering and the formation of crystalline phases is shown. • At the initial stage of crystallization in the amorphous matrix the formation of crystalline two-phase substructures is observed. [ABSTRACT FROM AUTHOR]

• The magnetic anisotropy angles of the coating were calculated using the least squares method. • Using the method of Chemical Plating under DC Current, a maximum GMI ratio of 1964 % and a field sensitivity of 463 %/Oe were achieved when the DC current was 50 mA. • Under the CPUDC method, the relationship between the plating thichness, composition and the DC currect was analyzed. NiFeP/Cu composite wires were fabricated by chemical plating under DC current. In this work, DC current was adjusted from 0 to 100 mA and the influence of current on the surface morphology, magnetic properties and GMI effect was investigated. It is found that the DC current has little impact on the composition of the coating. However, with the change of current, the surface morphology, plating rate and magnetic properties of the coating have undergone significant changes which in turn affect the GMI effect. As a result, when the appropriate current is applied, a transverse magnetic structure with an anisotropy angle of approximately 26 degrees can be generated, enabling a maximum GMI ratio of 1964 % and a field sensitivity of 463 %/Oe, which shows potential practical application in the magnetic sensors. [ABSTRACT FROM AUTHOR]

Background: Subjects with frozen shoulder (FS) might not be comfortable with vigorous physical therapy. Clinical trials assessing the effect of graded motor imagery (GMI) in FS are lacking. The aim of this study was to determine the effect of GMI as an adjunct to conventional physiotherapy in individuals with painful FS. Methods: Twenty subjects aged 40--65 years having stage I and II of FS were randomly divided into two study groups. The conventional physiotherapy group (n = 10) received electrotherapy and exercises while the GMI group (n = 10) received GMI along with the conventional physiotherapy thrice a week for 3 weeks. Pre- (Session 1) and post- (Session 9) intervention analysis for flexion, abduction, and external rotation range of motion (ROM) using a universal goniometer, fear of movement using the fear avoidance belief questionnaire (FABQ), pain with the visual analogue scale, and functional disability using the shoulder pain and disability index (SPADI) was done by a blinded assessor. Results: Statistically significant difference was seen within both the groups for all the outcomes. In terms of increasing abduction ROM as well as reducing fear of movement, pain, and functional disability, the GMI group was significantly better than control group. However, both groups were equally effective for improving flexion and external rotation ROM. Conclusions: Addition of GMI to the conventional physiotherapy proved to be superior to conventional physiotherapy alone in terms of reducing pain, kinesiophobia, and improving shoulder function for stage I and II of FS. [ABSTRACT FROM AUTHOR]

Influence of Joule heating on magnetic properties and GMI effect of Fe75B9Si12C4 glass-coated microwires was studied. A decrease in coercivity after Joule heating is observed, while hysteresis loops of Joule heated samples maintain a rectangular shape. However, a remarkable increase in GMI ratio is observed in Joule heated samples. Observed GMI ratio improvement has been discussed considering magnetic anisotropy induced by Oersted magnetic field during Joule heating and internal stress relaxation. A remarkable GMI effect improvement observed in Joule heated Fe-rich microwires, along the fact that Fe is a more common, less expensive metal than Co, makes them suitable for magnetic sensor applications. [ABSTRACT FROM AUTHOR]

The dependence of a longitudinal giant magnetoimpedance (GMI) effect of a [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element on the position of a magnetic insert is investigated in a model experiment on detecting a clot in a blood vessel. The magnetic insert is an epoxy composite containing 30 wt.% of the iron oxide microparticles. An investigation of the magnetic properties of the film element and the magnetic composite cylinder-shaped sample is performed. The magnetic insert is placed at a distance of 1.1 mm above the film surface and can be displaced perpendicular to its longer side with a step of 1 mm. As soon as the magnetic insert approaches the element, the maximum value of magnetoimpedance (MI) ratio for resistance is observed to decrease, and there is a shift of the curves of the MI ratio for resistance along the external magnetic field lines. The magnetic stray fields influencing the film in each position of the magnetic insert are simulated with the Comsol software and compared with the GMI response. [ABSTRACT FROM AUTHOR]

The 3-D physical models for FeNi/Cu/FeNi films with two different types of structures that are linear and meander are developed. The relationship between the impedance of the films and the applied magnetic field or excitation frequency is obtained, and the influence of geometric parameters and structures of the films on the giant magnetoimpedance (GMI) effect is analyzed. The result shows that the GMI effect in the film with a horizontal meander structure appears to be much stronger compared with that in a linear structure. The negative mutual inductance of the meander FeNi/Cu/FeNi films reduces the total inductance and decreases the frequency response. Meanwhile, the GMI effect and the negative mutual inductance are enhanced by increasing the number of turns or decreasing the space width between each segment. Based on these effects, the FeNi/Cu/FeNi film with a vertical meander structure is proposed and simulated, which reflects the design of the meander structure in the thickness direction. The distance between each segment is reduced to 500 nm. The GMI effect and the negative mutual inductance are greatly enhanced (the maximum value of the GMI ratio increases from 207% to 1247% when the excitation frequency changes from 50 to 300 MHz). Furthermore, the spatial resolution of the film is further improved. The results obtained could be useful both for a better understanding of the GMI effect of the FeNi/Cu/FeNi film with a meander structure and for providing a choice for the device preparation of highly sensitive magnetic sensors. [ABSTRACT FROM AUTHOR]

In order to study the influence of semiconductors on the magnetic properties and giant magnetoimpedance effect of FINEMET ribbon, titanium dioxide coating layer with different thickness was sputtered onto the free surface of the FINEMET ribbon by RF magnetron sputtering to prepare the FINEMET/TiO2 composite ribbons. The morphology, magnetic properties, and giant magnetoimpedance of the FINEMET/TiO2 composite ribbons were analyzed. The results show that the GMI ratio of composite ribbons first increases and then decreases with the increase of TiO2 layer thickness (0 ~ 150 nm). When the thickness of TiO2 thin film is 100 nm, the GMI ratio reaches the maximum 57.3%, which indicates that a certain thickness of TiO2 thin film can significantly improve the GMI effect. The result can be explained by the combined result of electromagnetic interaction and stress between TiO2 thin film and the FINEMET ribbon. [ABSTRACT FROM AUTHOR]

Visualization of training effectiveness is critical to patients' confidence and eventual rehabilitation. Here, an innovative magnetoinductive pressure sensor is proposed for monitoring hand rehabilitation in stroke hemiplegic patients. It couples the giant magneto and stress-impedance effects of a square spiral amorphous wire with the giant magnetoelastic effect of a polymer magnet (NdFeB@PDMS). The addition of the magnetoelastic layer results in a sensitivity improvement of 178%, a wide sensing range (up to 1 MPa), fast response/recovery times (40 ms), and excellent mechanical robustness (over 15 000 cycles). Further integration with an LC oscillation circuit enables frequency adjustment into the MHz range resulting in a sensitivity of 6.6% kPa -1 and outstanding linearity (R 2 =  0.99717) over a stress range of up to 100 kPa. When attached to a commercial split-fingerboard, the sensor is capable of dynamically monitoring the force in each finger, providing a reading of the rehabilitation process. Unlike conventional inductive sensors, the sensor is based on an inductive force-responsive material (amorphous wire), which significantly boosts the sensitivity. The approach also demonstrates the potential of magnetoelasticity in static pressure sensing, which is highly sensitive to dynamic pressure only through electromagnetic induction. This makes it more suitable for long-term and continuous human health monitoring., (© 2024 Wiley‐VCH GmbH.)

The magnetic, thermodynamic, and electrical/thermal transport properties of the caged-structure quasi-skutterudite Gd3Ir4Sn13 are re-investigated. The magnetization M(T), the specific heatCp(T)Cp(T), and the resistivityρ(T)ρ(T) reveal a double-phase transition—at TN1?~?10?K and at TN2?~?8.8?K—which was not observed in the previous report on this compound. The antiferromagnetictransition is also visible in the thermal transport data, thereby suggesting a close connection between the electronic and lattice degrees of freedom in this Sn-based quasi-skutterudite. The temperature dependence of ρ(T)ρ(T) is analyzed in terms of a power-law for resistivity pertinent to Fermi liquid picture. Giant, positive magnetoresistance (MR)?≈?80% is observed in Gd3Ir4Sn13 at 2?K with the application of 9?T. The giant MR and the double magnetic transition can be attributed to the quasi-cages and layered antiferromagneticstructure of Gd3Ir4Sn13 vulnerable to structural distortions and/or dipolar or spin-reorientation effects. The giant value of MR observed in this class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of this work. [ABSTRACT FROM AUTHOR]

The magnetic, thermodynamic, and electrical/thermal transport properties of the caged-structure quasi-skutterudite Gd3Ir4Sn13 are re-investigated. The magnetization M(T), the specific heatCp(T)Cp(T), and the resistivityρ(T)ρ(T) reveal a double-phase transition—at TN1?~?10?K and at TN2?~?8.8?K—which was not observed in the previous report on this compound. The antiferromagnetictransition is also visible in the thermal transport data, thereby suggesting a close connection between the electronic and lattice degrees of freedom in this Sn-based quasi-skutterudite. The temperature dependence of ρ(T)ρ(T) is analyzed in terms of a power-law for resistivity pertinent to Fermi liquid picture. Giant, positive magnetoresistance (MR)?≈?80% is observed in Gd3Ir4Sn13 at 2?K with the application of 9?T. The giant MR and the double magnetic transition can be attributed to the quasi-cages and layered antiferromagneticstructure of Gd3Ir4Sn13 vulnerable to structural distortions and/or dipolar or spin-reorientation effects. The giant value of MR observed in this class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of this work. [ABSTRACT FROM AUTHOR]

The integration of complete Boolean logic gate and memory in a single device is imperative to develop future computing systems beyond von Neumann architecture. Specifically, the giant magnetoimpedance (GMI) effect has drawn much attention for the high sensitive magnetic sensor applications; however, its possible application in logic-in-memory devices has been rarely explored. This work studies the butterfly-shaped hysteresis GMI effect in the self-biased magnetic heterogeneous laminate (Ni/Fe25Ni54Co15Si1B5/micro-planar coil/Fe25Ni54Co15Si1B5/micro-planar coil/Fe25Ni54Co15Si1B5/Ni) theoretically and experimentally. The proposed theoretical model based on the nonlinear constitutive model of magnetostrictive material, magnetic charge theory, and Maxwell equations indicates that the permeability of Fe25Ni54Co15Si1B5 ribbon is modulated by the varied remanent magnetostatic field and magnetostrictive stress of neighboring Ni ribbon simultaneously, which demonstrates multilevel remanent magnetoimpedance after the external magnetic field is turned off. This is useful for the nonvolatile multistate memory application. Furthermore, 16 complete nonvolatile Boolean logic functions can be also implemented in a single GMI device within three operation cycles. This study provides a promising candidate for future logic-in-memory architecture. [ABSTRACT FROM AUTHOR]

The close coupling between the spin and momentum degrees of freedom in topological insulators (TIs) presents the opportunity for the control of one to manipulate the other. The momentum can, for example, be confined on a curved surface and the spin influenced by applying a magnetic field. In this work, we study the surface states of a cylindrical TI magnetized in the x direction perpendicular to the cylindrical axis lying along the z direction. We show that a large magnetization leads to an upwards bending of the energy bands at small ∣kz∣. The bending leads to an anomalous magnetoresistance where the transmission between two cylinders magnetized in opposite directions is higher than when the cylinders are magnetized at intermediate angles with respect to each other. [ABSTRACT FROM AUTHOR]

We have experimentally investigated the crystal orientation dependence of band matching in current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo-spin-valves using Co2Fe(Ge0.5Ga0.5) (CFGG) Heusler alloy ferromagnetic layer and NiAl spacer. The high quality epitaxial CFGG/NiAl/CFGG all-B2-trilayers structure devices were fabricated on both MgO(001) and sapphire (1120) single crystal substrates to create (001) and (110) crystal orientations. Same magneto-transport properties were observed from these two differently orientated devices indicating that there is no or little orientation dependence of band matching on MR output. We also found that all-B2-trilayer structure was free of lattice matching influence depending on the crystal orientation, which made it a good candidate for CPP-GMR device. [ABSTRACT FROM AUTHOR]

This paper presents a novel microfluidic chip for in-vitro detection of biomolecules tagged by magnetic microparticles (MAPs) suspended in a static fluid. The system consists of two microfluidic channels: a reference channel in which bare MAPs are suspended and a detection channel in which magnetically tagged biomolecules are suspended (LMAPs). The LMAPs are functionalized MAPs (of the same magnetic volume as the ones in the reference channel) with attached biomolecules. The overall, non-magnetic volume of the LMAPs is greater than that of the bare MAPs. Current carrying microconductors are positioned underneath the channels in order to impose a magnetic field gradient to the MAPs and LMAPs and move them from the inlet to the outlet of the channels without flow. The innovative aspect of the proposed method is that the induced velocity on the MAPs and LMAPs, while imposed to the same magnetic field gradient, is inversely proportional to their overall, non-magnetic volume. This is due to the enhanced Stokes drag force exerted on the LMAPs, resulting from the greater volume and altered hydrodynamic shape. This induced velocity is measured by utilizing Giant Magnetoresistance (GMR) sensor pairs fabricated underneath the first and the last microconductors. Detected differences in velocity between the LMAPs and the reference MAPs indicate the presence of biomolecules in the static liquid sample. We also present a novel method for signal acquisition and demodulation: expensive function generators, data acquisition devices, and lock-in amplifiers were substituted by a generic PC sound card and an algorithm combining the Fast Fourier Transform of the signal with a peak detection routine. Experiments with functionalized MAPs and magnetically tagged Escherichia coli (representing the LMAPs) were carried out as a proof of concept. In order to identify the detection limit of the GMR sensor, single MAP (2.8 μm diameter) detection was performed. [ABSTRACT FROM AUTHOR]

The giant magnetoimpedance (GMI) effect, as well as the magnetic and magneto-optical properties, of Co69.2Fe4.1B11.8Si13.8C1.1 and Fe73.8Cu1Nb3.1B9.1Si13 amorphous microwires is studied. It is observed that the magnetic properties and the GMI effect of the Co-rich microwire can be tuned by heat treatment. A high GMI effect has been observed in as-prepared Co-rich microwires. After appropriate annealing of the Co-rich microwires, fast domain wall propagation and a GMI effect can be simultaneously observed in the same sample, and annealing is seen to affect both the diagonal and off-diagonal GMI components. Using complementary studies of the bulk and surface magnetic properties, an attempt is made to explain the great difference observed in the GMI properties of Co- and Fe-based microwires exhibiting very similar bulk hysteresis loops. [ABSTRACT FROM AUTHOR]

Herein, detailed studies on the influence of stress annealing on the magnetic softness and giant magnetoimpedance (GMI) ratio of Co69.2Fe3.6Ni1B12.5Si11 Mo1.5C1.2 glass-coated microwires are provided. As-prepared microwire presents linear hysteresis loops, moderate GMI ratio with double-peak magnetic field dependence and low coercivity (4 Am-1), typically observed for wires with transverse magnetic anisotropy. However, after conventional annealing magnetic hardening and transformation of linear hysteresis loop into rectangular with coercivity about 90 Am-1 is surprisingly observed. It is shown that stress annealing allows preventing magnetic hardening and remarkably improving GMI ratio. Properly stress-annealed samples present better magnetic softness: almost unhysteretic loops with coercivity about 2 Am-1 and magnetic anisotropy field about 35 Am-1. Observed stress-annealing-induced anisotropy is affected by the tensile stresses, applied during annealing and by the annealing temperature. From the frequency dependence of the maximum GMI ratio, the optimum frequency ranges for as-prepared and stress-annealed samples are determined. The observed stress-annealing-induced magnetic anisotropy and associated changes in magnetic properties and GMI effect are discussed in terms of internal stresses relaxation and related modification of the magnetostriction coefficient, "back stresses," structural anisotropy, redistribution of internal stresses, and change of spatial distribution of magnetic anisotropy. [ABSTRACT FROM AUTHOR]

A magnetic field sensor was developed using the asymmetric giant magnetoimpedance (AGMI) effect. Amorphous ferromagnetic (Fe0.06Co0.94)72.5Si12.5B15 wires were used in this study. The 2-cm-long wire showed an approximately 88% giant magnetoimpedance effect, and the 7-cm-long wire showed an approximately 197% giant magnetoimpedance effect. When two micromagnets were placed 1 cm from the ends of the wire, a distortion in the two peak shapes of the GMI curve was observed, and asymmetry was created by the micromagnets. The 7-cm-long wire showed an approximately 148% AGMI effect. A simple and a new approach was designed to develop a magnetic field sensor. In the design circuit, two signal generators were used to arrange the linearity and dc offset in the output signal. The circuit output showed good linearity and zero hysteresis in the ± 250 A/m and ± 50 A/m magnetic field regions for the 2-cm-long and 7-cm-long wires, respectively. [ABSTRACT FROM AUTHOR]

We measured the magnetostriction coefficient using small angle magnetization rotation method in amorphous ferromagnetic glass-coated Fe, Co, FeCo, and FeCoNi-based microwires. It was found that when the metallic nucleus of the microwire has a high magnetostriction—of the order (10-30) × 10-6 for FeCo-based microwires, the changing of diameters ratio, and hence, the magnitude and distribution of mechanical stresses have no significant effect on the value of the magnetostriction coefficient. In the case of nearly zero magnetostrictive FeCoNi-based microwires, increasing of the ⇔-ratio leads to decreasing in the absolute value of the magnetostriction coefficient. [ABSTRACT FROM AUTHOR]

We performed thermoplastic forming (TPF) on FeCoNbB metallic glass ribbons with a supercooled liquid region exceeding 100K, and found the sample after TPF is still completely amorphous. More importantly, the giant magnetoimpedance (GMI) effect was improved after the forming process: the maximum GMI ratio and sensitivity increased from 41% to 12.3%/Oe in the case of as-cast sample to 280% and 358.2%/Oe in the case of resulting sample after TPF, respectively. The hysteresis loops and domain patterns were subsequently studied, which revealed that the primary factor leading to the improvement of the GMI effect was the enhanced longitudinal magnetic anisotropy induced by the TPF process. We therefore assume that TPF is an effective way that improves the GMI effect, which differs from conventional annealing methods. [ABSTRACT FROM AUTHOR]

This work presents the adaptation of the Quality by Design (QbD) approach for application in the quality assurance of a biomedical measuring system under development. First attempts in applying QbD to biomedical technologies indicated a significantly higher number of parameters than its traditional application in the pharmaceutical industry. These preliminary studies did not fulfill the QbD stage of Design Space (DS) configuration for biomedical devices, an essential step to identifying the proper operating ranges of parameters and guaranteeing quality features. Therefore, it persisted the challenge of configuring DS for health devices, overcoming dependences in the interaction of multiple process parameters and critical attributes. The present work develops a hybrid QbD-Fuzzy approach for multiparametric DS configuration. The proposed method was applied in the development phase of a low-cost and high-sensitive magnetic measuring system for locating metallic foreign bodies in patients, employing sensors based on the Giant Magnetoimpedance effect. The results provided the acceptable operating ranges of the multiple process parameters to ensure the biomedical equipment's suitability. The proposed strategy contributes to the QbD implementation in biomedical technologies and, therefore, promotes the reliability of diagnostic and therapeutic results in the clinical environment. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the influence of structure parameters on giant-magnetoimpedance (GMI) effect measured by non-contact method. Design/methodology/approach: The GMI sensor contains a Co-based internal magnetic core fabricated by laser cutting and an external solenoid. The influences of magnetic permeability of magnetic core and structure parameters on GMI effect were calculated in theoretical model. The output impedance, resistance, reactance and GMI ratio were measured by non-contact method using impedance analyzer. Findings: Enhancing external magnetic field intensity can decrease the magnetic permeability of core, which has vital influences on the magnetic property and the output response of GMI sensor. In addition, increasing the width of magnetic core and the number of solenoid turns can increase the maximum GMI ratio. The maximum GMI ratio is 3,230% with core width of 6 mm and solenoid turns of 200. Originality/value: Comparing with traditional contact-measured GMI sensor, the maximum GMI ratio and the magnetic field sensitivity are improved and the power consumption is decreased in non-contact measured GMI sensor. GMI sensor measured by non-contact method has a wide range of potential applications in ultra-sensitive magnetic field detection. [ABSTRACT FROM AUTHOR]