Multilayer graphene-coated Co-based amorphous wires were fabricated by repeated PMMA-assisted transfer processing. Torsional deformation was introduced at different stages of shell construction to investigate the influence of fabrication sequence on the giant magnetoimpedance (GMI) effect. For the non-torsion series, the maximum GMI ratio increased from 165% for the as-spun wire to 302% after three graphene-coating cycles. A further enhancement to 353% was achieved when torsion was introduced after partial shell formation, whereas only a marginal improvement was observed when torsion was applied to bare amorphous wires. Magnetic measurements revealed concurrent reductions in coercivity and peak field together with a systematic evolution of the optimal operating frequency. These correlated changes suggest that progressive shell construction modifies the near-surface magnetic state via electromagnetic boundary modulation, while torsion introduced after partial shell formation provides additional interfacial strain tuning of the graphene-modified near-surface magnetic state, further optimizing low-field circumferential permeability. The results indicate that fabrication-sequence control provides an effective approach for tailoring the GMI response of composite amorphous wires and offers potential for the development of high-sensitivity magnetic sensing devices.

High-frequency giant magnetoimpedance (GMI) and giant stress-impedance (GSI) effects are promising for highly sensitive magnetic and stress sensing. In this work, laminated composites (LCs) based on Metglas 2714A ribbons coated with magnetic nanofilms were fabricated using photolithography, wet etching and magnetron sputtering. Three magnetic nanofilms, CoTaZr (S1), FeCoGa (S2) and CoFe2O4 (S3), were deposited at a thickness of 100 nm, and CoTaZr layers from 20 to 200 nm were further examined. The influence of nanofilm type and thickness on structure, morphology, magnetic properties and GMI or GSI performance was systematically analyzed. S1 showed the smoothest surface with roughness of about 11.46 nm and low coercivity of 4.8 Oe, and reached the highest GMI ratio of about 160 percent at 150 nm. S2 yielded the largest GSI of about 31 percent at 10 MPa. These results confirm that rational nanofilm design effectively enhances GMI or GSI responses.

Background noise and intensive sample preparation frequently compromise the field screening of Bacillus anthracis. Addressing these analytical bottlenecks, we constructed a giant magnetoresistive (GMR) biosensor incorporating geometrically tailored trapezoidal magnetic flux concentrators (MFCs). 3D finite element magnetic simulations directed the MFC topology to mitigate edge saturation, reconciling central magnetic gain with spatial uniformity. The resulting platform demonstrated a 100-fold sensitivity improvement over recent electrochemical methods, achieving a limit of detection (LOD) of 10 CFU/mL in standard buffers, with the entire testing process completed within 40 min. Direct target quantification remained viable in heterogeneous matrices—muddy water, whole milk, and apple cider—circumventing tedious pretreatment. This geometric and magnetic optimization yields a pragmatic sensing architecture tailored for on-site biodefense monitoring.

A highly potent greenhouse gas, sulfur hexafluoride (SF6), requires efficient capture from industrial SF6/N2 mixtures. Herein, a series of benzene-rich hyper-cross-linked polymers (PPBx) were synthesized via a low-cost Friedel-Crafts alkylation reaction using alpha,alpha '-dichloro-p-xylene (DCX) and triphenylbenzene (TPB) at different molar ratios. The abundant benzene rings in the material enable strong F-pi interactions with SF6, while the hierarchical micromesoporous structure ensures high adsorption capacity. Adsorption tests revealed that PPB1, fabricated at a DCX/TPB molar ratio of 3:1, achieved a remarkably high SF6 uptake of 2.05 mmol/g at 298 K and 1 bar and an impressive SF6/N2 ideal adsorbed solution theory selectivity of 120 at 298 K. In addition, the dynamic separation performance for SF6/N2 was up to 1274.6 s/g, also demonstrating excellent properties under actual operating conditions. The PPB1 material also demonstrates excellent thermal stability and cycling performance. This work provides a cost-effective and highly efficient hyper-cross-linked polymeric adsorbent with high potential for industrial SF6 separation and recovery.

Co-based amorphous wires (Co-AWs) are functional materials renowned for their high impedance change rate in magnetic fields and a pronounced giant magnetoimpedance (GMI) effect. In this study, magnetron sputtering (MS) and dip-coating (DC) techniques were employed to fabricate carbon-based nanocoatings aimed at modulating the GMI properties of Co-AWs. The magnetic properties and GMI responses of the composite Co-AWs with carbon-based coatings were comparatively analyzed. The results demonstrate that both methods effectively enhanced the GMI properties of the coated Co-AWs. The DC method emerged as a rapid and efficient approach for forming the coated film, achieving a modest enhancement in GMI performance (10% enhancement). In contrast, the MS technique proved more effective in improving the GMI effect, yielding superior results. Co-AWs coated via Ms exhibited smoother surfaces and reduced coercivity. Notably, the GMI effect increased with the thickness of the sputtered carbon coatings, reaching a maximum GMI effect of 522% (a remarkable 357% enhancement) and a sensitivity of 33.8%/Oe at a coating thickness of 334 nm. The observed trend in the GMI effect with carbon layer thickness corresponded closely to variations in transverse permeability, as determined by vibrating sample magnetometry (VSM). Furthermore, the carbon coating induced changes in the initial quenching stress on the surface of the Co-AWs, leading to alterations in impedance and a significant reduction in the characteristic frequency of the Co-AWs. Our findings provide valuable insights into the modulation of GMI properties in Co-AWs, paving the way for their optimized application in advanced magnetic sensor technologies.

Magnetostrictive thin films deposited on flexible substrates have garnered significant attention due to their diverse applications in flexible magnetoelectronic devices, including flexible magnetic memory devices, sensors, and high-frequency devices. In this work, magnetostrictive FeCoGa thin films were deposited on polyimide (PI), polyester (PET), and mica flexible substrates. The rectangular and dumbbell-shaped thin film patterns with varying sizes were designed and implemented using microelectromechanical systems (MEMS) technology. The films were characterized using scanning electron microscopy (SEM), x-ray diffraction (XRD), vibrating sample magnetometry (VSM), and impedance analyzer. The results showed that magnetostrictive amorphous FeCoGa films were effectively formed on these flexible substrates. The patterns on the PI substrate exhibited low coercivity and the highest quality factor, while the patterns on the mica substrate demonstrated the lowest residual magnetism. The dumbbell-shaped patterns exhibited higher magnetic response sensitivity than the rectangular film patterns. Notably, the variation in resonance frequency between the array patterns was extremely small, at less than 0.18%, indicating excellent reproducibility and consistency of the magnetic properties of the patterns. The results confirmed the superior performance of dumbbell-shaped FeCoGa magnetostrictive film patterns on flexible substrates, providing valuable insights for the design of flexible magnetostrictive sensors.

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.

Giant Magnetoimpedance (GMI) is attracting attention for its high sensitivity in the presence of an applied magnetic field. Although the GMI effect has been studied for many years, it is difficult to analyze the magnetic interactions between coating layer and ribbon by hysteresis loops for composite ribbons with a large difference in thickness between the soft magnetic alloy and film. Therefore, the magnetic interactions of FINEMET ribbon coated with different thicknesses of SiO 2 and FePt films on the free side were thoroughly analyzed by GMI. The dipolar interactions decrease with the increase of thickness of SiO 2 layer. The GMI ratio of FINEMET/SiO 2/ FePt composite ribbons reaches 57% and characteristic frequency decreases to 800 kHz. These results could provide a way to analyze the magnetic interactions in composite ribbons.

In this work, micro-ribbon strips and meanders based on CoFeNiSiB amorphous ribbons were fabricated by using the lithography technique and chemical etching. Flat and curved holders with different radius of curvature were obtained via 3D printing techniques for GMI testing. Longitudinal and transverse GMI (LGMI and TGMI) behaviors of micro-ribbon sensors in different bending directions and degrees were systematically investigated. The results show the LGMI and TGMI effects of micro-ribbon meanders with one turn is most sensitive to bending. It can be used in the development of deformation sensors. In addition, there is a linear range of field in the LGMI and TGMI curves of micro ribbons under different bending conditions, and the sensitivity of micro-ribbon sensors shows no significant change in the range. In particular, the micro-ribbon meanders with three turns are the least sensitive to bending deformation and can be used to develop stable and flexible GMI sensors for wearable electronics devices.

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.

Quenched Co-based ribbon strips are widely used in the fields of magnetic amplifier, magnetic head material, magnetic shield, electric reactor, inductance core, sensor core, anti-theft system label, and so on. In this study, Co-based composite CoFeNiSiB ribbon strips with a micron width were fabricated by micro-electro-mechanical systems (MEMS) technology. The carbon and FeCoGa nanofilms were deposited for surface modification. The effect of carbon and FeCoGa nanofilm coatings on the crystal structure, surface morphology, magnetic properties, and magnetoimpedance (MI) effect of composite ribbon strips were systematically investigated. The results show that the surface roughness and coercivity of the composite ribbon strips are minimum at a thickness of the carbon coating of 60 nm. The maximum value of MI effect is 41% at 2 MHz, which is approximately 2.4 times greater than plain ribbon and 1.6 times greater than FeCoGa-coated composite ribbon strip. The addition of a carbon layer provides a conductive path for high frequency currents, which effectively reduces the characteristic frequency of the composite ribbon strip. The FeCoGa coating is able to close the flux path and reduce the coercivity, which, in turn, increases the transverse permeability and improves the MI effect. The findings indicate that a successful combination of carbon layer and magnetostrictive FeCoGa nanofilm layer can improve the MI effect and magnetic field sensitivity of the ribbon strips, demonstrating the potential of the composite strips for local and micro area field sensing applications.

The impact of TiO2 and Fe20Ni80 coating layer on roughness, magnetic properties, giant magneto-impedence (GMI) effect and dipole interactions of FINEMET/TiO2/Fe20Ni80 composite ribbons were investigated systematically. The TiO2 layer can effectively tune transverse magnetic structure and GMI ratio of composite ribbons. More TiO2 coating layer thickness deteriorates the magnetic properties, and dipole interactions decrease owing to the distance between FINEMET ribbon and Fe20Ni80 layer increases. When the thickness of TiO2 is 100 nm, composite ribbons exhibit small roughness of 8.5 nm, a large GMI ratio of 63% at 0.8 MHz, dipole field of 1.0 Oe, which is superior to other semiconductor composite ribbons. The variation in GMI ratio can be explained as the change of transverse permeability, and the decrease of magnetic dipole interactions can be explained as the change of distance between the FINEMET ribbon and Fe20Ni80 layer. The results show that the combination of semiconductor and magnetic materials can realize the miniaturization of magnetic sensing, and it has a guiding role in the development of GMI effect and magnetic interactions theory of composite materials.

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.

对磁性传感器件的微电子机械系统(MEMS)加工技术以及在生物医学检测方面的应用进行了简单阐述,分析了磁性生物传感技术的工作原理,重点介绍了巨磁阻抗(GMI)、巨磁阻(GMR)和微磁通门传感器的MEMS制备工艺,其中详述了磁性传感器的材料、几何尺寸、结构以及基底对其性能的影响,总结了磁性生物传感器在生物检测中的研究进展,重点阐述了磁性生物传感器在磁性标签、癌症标志物、食源性细菌、病毒以及细胞检测方面的应用.最后,对当前磁性生物传感器在生物医学检测领域面临的问题进行了简要分析,并对磁性生物传感器未来的应用前景进行了展望,以期为研发新一代可用于临床检测磁性生物检测系统打下良好的基础.

A new three-axis inertial switch is proposed. The triangle-structured movable electrode is designed to improve the inertial switch’s dynamic response performance, especially the movable electrode’s dynamic stability performance. The static mechanical analysis indicated that the displacement of the movable electrode to the fixed electrode in the sensitive direction is the minimum when the acceleration is applied to this designed inertial switch. The dynamic simulation analysis showed that the threshold of the designed inertial is about 235 g. The threshold in the non-sensitive direction is about 240 g, 270 g, 300 g, and 350 g when the directions of applied acceleration deviate 15°, 30°, 45°, and 60° from the sensitive direction, respectively. These results indicated that the designed inertial could resist the impact in non-sensitive directions and improve the stability in sensitive directions. The prototype of the inertial switch was fabricated and tested successfully. The testing results indicate that the threshold of the fabricated inertial switch is about 219 g. The test results verify the dynamic stability performance of the designed inertial switch.

Micropatterned Co-based amorphous ribbon meanders were prepared by MEMS technology on the flexible PET substrate. Different holders with varying arch heights were fabricated through 3D printing technology and used for carrying out tensile stresses. The giant magnetoimpedance (GMI) ratio was investigated under different tensile stress inductions (0~88 MPa). The results indicate that the GMI ratio of the flexible ribbon meanders is significantly impacted due to presence of tensile stress. As tensile stress increases, the GMI ratio first increases and then decreases. The maximum GMI ratio of 28.38% is achieved at a tensile stress level of 11 MPa. Additionally, the peak field gradually approaches zero as stress increases. When tensile stress increases from 0 MPa to 88 MPa, the peak field is shifted by 10.59 Oe.

Excess lead iodide (PbI2 ), as a defect passivation material in perovskite films, contributes to the longer carrier lifetime and reduced halide vacancies for high-efficiency perovskite solar cells. However, the random distribution of excess PbI2 also leads to accelerated degradation of the perovskite layer. Inspired by nanocrystal synthesis, here, a universal ligand-modulation technology is developed to modulate the shape and distribution of excess PbI2 in perovskite films. By adding certain ligands, perovskite films with vertically distributed PbI2 nanosheets between the grain boundaries are successfully achieved, which reduces the nonradiative recombination and trap density of the perovskite layer. Thus, the power conversion efficiency of the modulated device increases from 20% to 22% compared to the control device. In addition, benefiting from the vertical distribution of excess PbI2 and the hydrophobic nature of the surface ligands, the modulated devices exhibit much longer stability, retaining 72% of their initial efficiency after 360 h constant illumination under maximum power point tracking measurement.

Amorphous and nanocrystalline soft magnetic materials have attracted much attention in the area of sensor applications. In this work, the magnetoimpedance (MI) effect of patterned soft ferromagnetic meander-shaped sensor elements has been investigated. They were fabricated starting from the cobalt-based amorphous ribbon using the lithography technique and chemical etching. Three-turn (S1: spacing s = 50 m, width w = 300 m, length l = 5 mm; S2: spacing s = 50 m, width w = 400 m, length l = 5 mm) and six-turn (S3: s = 40 m, w = 250 m, length l = 5 mm; S4: s = 40 m, w = 250 m and l = 8 mm) meanders were designed. The n' shaped meander part was denominated as one turn. The S4 meander possesses a maximum MI ratio calculated for the total impedance Z/Z approximate to 250% with a sensitivity of about 36%/Oe (for the frequency of about 45 MHz), and an MI ratio calculated for the real part of the total impedance R/R approximate to 250% with the sensitivity of about 32%/Oe (for the frequency of 50 MHz). Chemical etching and the length of the samples had a strong impact on the surface magnetic properties and the magnetoimpedance. A comparative analysis of the surface magnetic properties obtained by the magneto-optical Kerr technique and MI data shows that the designed ferromagnetic meander-shaped sensor elements can be recommended for high frequency sensor applications focused on the large drop analysis. Here we understand a single large drop as the water-based sample to analyze, placed onto the surface of the MI sensor element either by microsyringe (volue range 0.5-500 L) or automatic dispenser (volume range 0.1-50 mL).

Cardiac biomarkers (CBs) are substances that appear in the blood when the heart is damaged or stressed. Measurements of the level of CBs can be used in course of diagnostics or monitoring the state of the health of group risk persons. A multi-region bio-analytical system (MRBAS) based on magnetoimpedance (MI) changes was proposed for ultrasensitive simultaneous detection of CBs myoglobin (Mb) and C-reactive protein (CRP). The microfluidic device was designed and developed using standard microfabrication techniques for their usage in different regions, which were pre-modified with specific antibody for specified detection. Mb and CRP antigens labels attached to commercial Dynabeads with selected concentrations were trapped in different detection regions. The MI response of the triple sensitive element was carefully evaluated in initial state and in the presence of biomarkers. The results showed that the MI-based bio-sensing system had high selectivity and sensitivity for detection of CBs. Compared with the control region, ultrasensitive detections of CRP and Mb were accomplished with the detection limits of 1.0 pg/mL and 0.1 pg/mL, respectively. The linear detection range contained low concentration detection area and high concentration detection area, which were 1 pg/mL–10 ng/mL, 10–100 ng/mL for CRP, and 0.1 pg/mL–1 ng/mL, 1 n/mL–80 ng/mL for Mb. The measurement technique presented here provides a new methodology for multi-target biomolecules rapid testing.

A sensitive and innovative assay system based on a micro-MEMS-fluxgate sensor and immunomagnetic beads-labels was developed for the rapid analysis of C-reactive proteins (CRP). The fluxgate sensor presented in this study was fabricated through standard micro-electro-mechanical system technology. A multi-loop magnetic core made of Fe-based amorphous ribbon was employed as the sensing element, and 3-D solenoid copper coils were used to control the sensing core. Antibody-conjugated immunomagnetic microbeads were strategically utilized as signal tags to label the CRP via the specific conjugation of CRP to polyclonal CRP antibodies. Separate Au film substrates were applied as immunoplatforms to immobilize CRP-beads labels through classical sandwich assays. Detection and quantification of the CRP at different concentrations were implemented by detecting the stray field of CRP labeled magnetic beads using the newly-developed micro-fluxgate sensor. The resulting system exhibited the required sensitivity, stability, reproducibility, and selectivity. A detection limit as low as 0.002 μg/mL CRP with a linearity range from 0.002 μg/mL to 10 μg/mL was achieved, and this suggested that the proposed biosystem possesses high sensitivity. In addition to the extremely low detection limit, the proposed method can be easily manipulated and possesses a quick response time. The response time of our sensor was less than 5 s, and the entire detection period for CRP analysis can be completed in less than 30 min using the current method. Given the detection performance and other advantages such as miniaturization, excellent stability and specificity, the proposed biosensor can be considered as a potential candidate for the rapid analysis of CRP, especially for point-of-care platforms.