基于巨磁阻抗效应的微磁传感器研制

分析了巨磁阻抗敏感材料CoFeSiB非晶丝的特性,研制了磁传感器的硬件系统并对其进行了标定.试验表明:基于巨磁阻抗效应的新型微磁传感器具有灵敏度高、饱和磁场低、响应快和稳定性好等优点,具有较好的应用前景.     

基于巨磁阻抗效应的生物磁敏传感器技术

巨磁阻抗(GMI)生物传感器是基于一些非晶磁性材料的高灵敏巨磁阻抗效应的一类新型生物传感器,具有灵敏度高、稳定性好等特点,发展前景广阔.该文对巨磁阻抗生物传感器的工作原理、研究现状和应用前景进行了概述.     

不同长度敏感元件的两种巨磁阻抗传感器传感性能研究

针对采用Co基非晶丝作为敏感元件的传统巨磁阻抗传感器和非对角巨磁阻抗传感器进行比较研究。改变敏感元件的长度,观察两者在直流外磁场作用下输出信号的变化规律,并讨论退磁场等因素对传感器输出信号的影响。结果显示非对角巨磁阻抗传感器具有高灵敏度,无磁滞等优点,且灵敏度随样品长度的减小略有增大,在测量弱磁场方面表现出更大的潜力,为磁敏传感器的小型化提供了一定的参考依据。     

高灵敏巨磁阻抗小型磁传感器研制

利用单辊快淬法制备了CoFeNiSiB非晶薄带,经过400 A/mm2电流密度、20 ms脉冲间隔条件下的脉冲退火后具有较好的弱磁场灵敏性能.以该带材为磁敏材料,基于纵向驱动方式研制了一种巨磁阻抗(GMI)磁传感器,该磁传感器尺寸小、灵敏度高、频率响应好,±0.05 mT弱磁场范围内灵敏度可达到44.15 V/mT,在高灵敏度小型磁传感器领域具有较大的应用潜力.     

非晶纳米晶带材巨磁阻抗磁传感器特性分析

利用非晶纳米晶带材的巨磁阻抗(GMI)效应制备一种磁传感器,在输出最大值的特定频率下,研究与带材轴线平行和垂直方向磁场的输出特性.研究表明:在10.5 MHz附近的激励频率作用下,传感器输出取得最大值;传感器对平行磁场有一段高灵敏的线性工作区间,对垂直磁场不响应;纳米晶带材GMI磁传感器的灵敏度高达0.669 1 V/Oe,优于非晶带材制备器件的灵敏度0.1483 V/Oe.     

基于CoFeNbSiB非晶丝巨磁阻抗效应的新型磁传感器

本文利用CoFeNbSiB非晶丝的巨磁阻抗（GMI）效应制作了一种新型微磁场传感器。该传感器尺寸小,灵敏度高,反应速度快,且不需要预热。文章中具体介绍了非晶丝的特性、传感器的硬件及软件设计。     

基于非晶合金非对称巨磁阻抗效应的磁传感器设计

以CoFeNiSiB非晶合金薄带为敏感材料,测试分析了其软磁性能,经空气中磁场退火热处理,获得了较好的非对称巨磁阻抗效应(AGMI).以磁场退火处理后的非晶合金薄带为敏感元件,设计了AGMI磁传感器,并对其性能进行了开环和闭环测试.测试结果表明,开环条件下该传感器表现出较高的灵敏度;闭环条件下则表现出更好的线性度和更宽...     

基于非晶带巨磁阻抗效应的新型弱磁场传感器

利用短时矩形脉冲电流对近零磁致伸缩系数钴基非晶态合金带进行退火处理,得到约114%的巨磁阻抗变化率.同时利用CMOS多谐振荡电路产生窄脉冲电流序列对前面处理过的非晶带进行激励,制作成灵敏度高、稳定性好、功耗低的弱磁场传感器.对传感器的工作原理进行了分析,并设计了信号处理电路.该传感器可应用于对弱磁场的检测.     

数字补偿式巨磁阻抗传感器设计

地磁环境下弱磁信号的检测要求地磁传感器具有灵敏度高、工作范围宽的特点,非晶丝在高频交流激励下具有阻抗变化率高的特点,宜于用来作地磁传感器.但非晶丝线性工作区较短,不能完全覆盖地磁场范围,通过采用数字补偿技术可以补偿大部分地磁场,使传感器工作于非晶丝的线性区,提高了传感器的灵敏度,扩展了传感器的工作范围.通过测试,采用数字补偿技术的巨磁阻传感器灵敏度为71. 133μV/nT,工作于-61 750. 8~73 774. 8 nT,与被测磁场的最大误差为2. 45 nT.     

地震波、空间磁变及预警研究

介绍了一种基于巨磁磁阻GMR效应的高灵敏度三维加速度传感器和相关的磁传感器构成的惠斯通电桥电路组成的探测系统,通过对地震波波相及其空间磁变现象进行实时监测,根据地震发生前及发生过称程中空间磁场突变特征,予以提前预警,预警时间可提前到10～25min。从震动和磁变两方面对地震进行实时监测,大大提高了探测及预警的准确度。     

A novel integrated microfluidic platform based on micro-magnetic sensor for magnetic bead manipulation and detection

We present a novel integrated microfluidic platform based on micro-magnetic sensor for manipulating and detecting magnetic beads (MB). A micro-spiral planar coil in MB manipulating system microfabricated by micro-electro-mechanical system technology is implemented to manipulate MB, and a giant magnetoimpedance (GMI) based micro-magnetic sensor is employed to detect the trapped MB. In our work, MB can be efficiently trapped by trapping force generated from micro-coil in microchannel. Next, trapped MB are detected by the changing ratio of impedance, as well as the variation of resistance and reactance in GMI sensor for trapped MB induce weak stray magnetic field under the magnetization by external magnetic field. The maximum difference of GMI ratio between with beads condition and without beads condition is 4.0% at the optimum driving frequency of 20 MHz under the external magnetic field of 15 Oe, and resistance ratio varies more significantly than reactance ratio. In comparison with traditional MB detecting methods by GMI sensor, the integrated microfluidic platform based on GMI sensor can not only manipulate and detect MB signal sensitively, but also enhance detection efficiency and decrease the experiment errors. Furthermore, this platform avoids contamination from the solutions in chemically reactive layers and reduces assay time in future biomarker detection. In our work, the microfluidic platform based on GMI sensor has potential applications in biomarker detection via MB manipulation and detection.     

GMI sensitive element based on commercial Vitrovac amorphous ribbon

A very high giant magnetoimpedance (GMI) up to 420% and sensitivities up to 60%/Oe have been achieved in commercial Vitrovac^® 6025 Co₆₇Fe₄Mo_1.5Si_16.5B₁₁ amorphous ribbons. A relatively low frequency range of 0.5–10 MHz and driving current intensities between 1.5 and 15 mA in combination with high sensitivities, low GMI hysteresis with respect to external magnetic field make this material very attractive for low field sensing processes. Special treatments under load without heating result in additional stability and favorable noise to signal ratio. We explain these outstanding GMI properties taking into account extra uniform magnetization processes and longitudinal magnetic anisotropy. The complex study of the magnetic and GMI properties shows, that equilibrium of various parameters of GMI medium is an additional guarantee of stable functionality.     

Study on the giant magnetoimpedance effect in micro-patterned Co-based amorphous ribbons with single strip structure and tortuous shape

Field-annealed Co-based commercial amorphous ribbons (Metglas^® 2714A) with single strip structure and tortuous shape are fabricated by MEMS technology. The influence of the size, magnetic field and frequency on the giant magnetoimpedance (GMI) ratio of the ribbons with single strip structure and tortuous shape is investigated. The results show that the GMI ratio of micro-patterned Co-based amorphous ribbons with single strip structure increases with increasing in length and decreases with the increasing in width. The ribbons (length = 10 mm, width = 250 μm) with single strip can get higher GMI ratio at lower frequency (<40 MHz). The GMI ratio of micro-patterned tortuous-shaped Co-based amorphous ribbon with six turns is biggest with 82 %, obtained at a frequency of 40 MHz and a field of 20 Oe, and the GMI ratio increases with the increasing in turn number from two turns to six turns. All mechanisms (line width and tortuous shape) that influence the inductance and resistance will result in changes in the impedance and the GMI effect. The anisotropy field H_K (15–20 Oe) of tortuous shape ribbon that the peak GMI ratio is larger than that (5–10 Oe) of the ribbon with single strip structure. The effect of the frequency on the GMI ratio of the ribbons with tortuous shape is more complex. This can be explanation by complex inductance of tortuous shape ribbons.     

Fabrication of symmetrical meandering NiFe/Cu/NiFe film sensors and study of the effects of field direction and film thickness on giant magnetoimpedance

Sandwich NiFe/Cu/NiFe film sensors with symmetrical meandering structure are fabricated by Micro-Electro-Mechanical-System (MEMS) technology, the longitudinal, transverse, and perpendicular giant magnetoimpedance (GMI) effect have been investigated comprehensively. The correlation between film thickness and GMI effect are analyzed thoroughly. The experimental results show that the alternating current (AC) frequency of maximum GMI ratio decreases gradually with the increasing of magnetic layer thickness, but the conducting layer exhibits an opposite tendency. The NiFe and Cu layer both show a GMI ratio tendency from increasing to decreasing along with the increase of film thickness. It is observed the longitudinal, transverse and perpendicular GMI effect share a common characteristic: the AC frequency of maximum GMI ratio increases with the increase of external field intensity. However, there is a notable difference between them, it is demonstrated that the higher GMI ratio and sensitivity can be obtained in the longitudinal direction. The longitudinal GMI ratio reaches the peak value 191.2 % at f _AC = 6.5 MHz under H _L = 17 Oe in six turns sample with the Cu and NiFe thickness of 6 and 7 μm, respectively.     

Temperature offset drift of GMI sensors

Temperature offset stability of magnetoimpedance sensor is discussed based on experiments accomplished with soft magnetic amorphous material. An amorphous ribbon of Co₆₇Fe₄Cr₇Si₈B₁₄ composition was tested in a magnetic shield with adjustable internal temperature. DC resistance and complex components of impedance at frequencies up to 30 MHz were investigated in the temperature range of −20 to +75 °C. The measured data were used for the evaluation of temperature dependence of transverse permeability that is assumed to be a major contributor to the temperature variations of impedance. We also show that thermal treatments of the amorphous ribbon significantly affect the temperature behaviour of GMI. In case of tested alloy, which has very small negative temperature coefficient of resistivity, the achieved equivalent temperature offset drift is −0.27 A/m/K (−340 nT/K).     

一种GMI传感器目标探测模型

为了使巨磁阻抗（ GMI）传感器能够在军事目标探测中发挥灵敏度高、探测距离远的特点,对其输出曲线处理方法进行改进,提出了基于幅值功率特征和小波特征的目标探测模型,既充分利用了敏感材料的GMI效应,又保证了测量的精度。最后通过模拟目标定位实验验证了该模型的有效性。该模型操作简单,易于实现,且定位精度较高,在目标探测与跟踪领域有很大的发展空间。     

宽线性GMI磁传感器的研制

用单辊快淬法制备的Fe76Si7.6B9.5P5C1.9非晶合金薄带,在540℃空气中退火后具有宽线性的磁敏特性。利用纵向驱动的方法研制一种巨磁阻抗（GMI）传感器,该磁传感器重复性好,迟滞误差小,在-0.3～＋0.3 kA·m-1范围具有比较好的线性度,灵敏度达到12.65mV/A·m-1。