Improved performance of the micro planar double-axis fluxgate sensors with different magnetic core materials and structures

As a classic weak magnetic field sensor, the fluxgate sensors have great potential application in many fields. This paper presents four kinds of the micro planar double-axis fluxgate sensors based on the MEMS technologies, which have different core materials and core structures. The core materials include electroplated permalloy, Co-based amorphous ribbon and Fe-based amorphous ribbon, and the core structures include single-layer open magnetic loop structure and double-layer closed magnetic loop structure. The sensor with closed double-layer Fe-based ribbon core exhibits a best sensitivity of 238 V/T due to reducing the magnetic flux leakage. The results show that the magnetic core with closed magnetic loop, high permeability and high saturation induction density will help increase the sensitivity of the micro double-axis fluxgate sensor.     

Improved micro fluxgate sensor with double-layer Fe-based amorphous core

A rapid manufacturing process for the micro solenoid fluxgate sensor integrating multilayer amorphous ribbon core has been established, which combines the micro assembling method and the MEMS technologies. We select Fe-based amorphous soft magnetic ribbons for core materials and have fabricated the micro fluxgate sensors by MEMS technologies, with single-layer core and double-layer core respectively. The micro fluxgate sensors with double-layer core show the advantageous to that with single-layer core and exhibit sensitivity of 1089.2 V/T at excitation current of 120 mA rms, wide linear range of ?900 to 900 μT and power consumption of 24.48 mW. The noise power density of the single core fluxgate sensor is 2.48nT/Hz^1/2@1 Hz.     

Low power integrated fluxgate sensor with a spiral magnetic core

Facing the new integrated applications, coordination between three parameters of the micro fluxgate sensor, namely, sensitivity, power consumption and operation range, is the key to make the applications come true. This paper reports a new low power micro integrated fluxgate sensor with low cost solution. A spiral electroplating permalloy magnetic core is introduced to reduce excitation current. Due to the design of little coils resistance and thick magnetic core, the fluxgate sensor exhibits a power consumption of 7.35 mW, a sensitivity of 117 V/T and a linear range of −200 to 200 μT. Compared with the constant-width magnetic core and the multi rectangular ring magnetic cores, experiment results show that the spiral magnetic core benefits both smaller excitation current and higher sensitivity. The newly developed fluxgate sensor maintains high sensitivity and wide linear range with low power consumption.     

Two-axis micro fluxgate sensor on single chip

We present a two-axis micro fluxgate sensor on single chip for electronic compassing function. To measure X- and Y-axis magnetic fields, functional two fluxgate sensors were perpendicularly aligned and connected each other. The fluxgate sensor was composed of square-ring shaped magnetic core and solenoid excitation and pick-up coils. The solenoid coils and magnetic core were separated by benzocyclobutane which had high insulation and good planarization characters. Copper coil patterns of 10 μm width and 6 μm thickness were electroplated on Ti (300 Å)/Cu (1,500 Å) seed layers. 3 μm thick Ni_0.8Fe_0.2 (permalloy) film for the magnetic core was also electroplated under 2,000 gauss. Excellent linear response over the range of ?100 μT to +100 μT was obtained with the sensitivity of ～280 V/T. Actual chip size was 3.1×3.1 mm². The sine and cosine signals of two-axis fluxgate sensor had a good function of azimuth compass.     

微型磁通门的优化分析与性能测试

对铁芯结构的改进有利于满足微型磁通门传感器降低功耗的要求,但不同的拓扑结构所取得的效果不同,为此对铁芯结构进行了优化分析,并采用MEMS工艺制备了不同铁芯结构的微型磁通门进行性能测试与对比验证.测试结果表明,优化后的多孔铁芯结构能更好的降低微型磁通门传感器的功耗与噪声,提高灵敏度,改善器件的整体性能.     

一种平面四轴向磁通门传感器的设计

设计了一种新型的四轴向磁通门传感器,可测量铁磁性目标经过时产生的磁异信号在四个轴向上的变化情况,通过各轴间的相关性即可判断出目标的运动方向。结构中将四个三端式磁通门探头单元相间45°摆放,使得传感器的任一侧都有四个磁场强度分量的输入,结合分时激励的方法,与传统磁通门传感器相比,其具有电路简单,灵敏度高、稳定性好、功耗小等优点。经实验表明,该传感器方向识别正确率可达85%以上,能够较好的应用于安防及侦测领域中对目标运动及其方向的监测。     

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.     

Analytical study on cantilever resonance type magnet-integrated sensor device for micro-magnetic field detection

A beam-shaped cantilever resonance type magnetic sensor device has been proposed with a micro magnet. Two structural designs, named as design 1 and design 2, have been comparatively analyzed using ANSYS in order to obtain larger frequency shifts (higher magnetism sensitivity) due to the applied exterior magnetic field. The analytical results show that, in the range of 0–10 mT, the frequency shifts are small, while under 100 mT, a relatively larger frequency shift of about 30 Hz can be theoretically obtained. The power consumption of the proposed devices has been further theoretically studied for preliminary understanding. Using the well-known displacement equations, the estimated power consumption is around 0.21 μW, which is very lower than that of the reported magnetic field sensors. This implies that it is possible to fabricate higher sensitive magnetic field sensor with lower power consumption.     

微型磁通门铁芯结构的拓扑分析与优化

多孔铁芯有利于满足微型磁通门传感器降低功耗的要求,但不同的拓扑结构所取得的效果不同,对多孔铁芯结构进行了拓扑分析与针对性优化,并采用微机电系统(MEMS)工艺制备了不同铁芯结构的微型磁通门进行性能测试与对比验证.实验结果证明:优化后的铁芯结构能更好地降低微型磁通门传感器功耗,提高器件整体性能.     

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...     

MEMS micro fluxgate sensors with mutual vertical excitation coils and detection coils

As a classic Earth magnetic field sensor, fluxgate magnetic sensors have great potential applications in many fields. This paper presents a new 3D micro-solenoid fluxgate magnetic sensor based on the MEMS technique. The excitation coils were placed vertically to the detection coils on the chip plane, around a rectangular shaped magnetic core. Polyimide was used to insulate coils and magnetic core. Width of copper conductor lines is 50 μm, and line space is 50 μm. The design of such fluxgate magnetic sensor followed second harmonic signal selecting method. Phase-lock amplifier was used to get second harmonic signal output by detection coils. The linear range of 0–80 μT with sensitivity of 6.7 V/T was achieved from the fabricated sensor with excitation current of 430 mA and the operational frequency of 40 KHz. As the excitation current was 470 mA, linear range of 0–50 μT with sensitivity of 21.7 V/T was achieved.     

Microfabrication of thin film temperature sensor for cryogenic measurement

In this paper, thin film Pt temperature microsensor in the temperature range of 10–100 K for cryogenic engineering applications is proposed and researched. The sensor is designed with two structures, and they are obtained by micro fabrication technology. The sensors are annealed in different conditions. The degree crystallization and grain size are analyzed by X-ray diffraction and SEM for both as-deposited and annealed sensors. The resistance dependency on temperature test result shows that when temperature is larger and smaller than 50 K, the average temperature coefficient resistance (TCR) of rectangular shape sensor could achieve 3,118 ppm/K and above 257 ppm/K, respectively. Meanwhile, TCR of circular shape sensor is 2,778 ppm/K and above 249 ppm/K, respectively. The good thermal cycle stability is observed. After three cycles between 10 and 100 K, the maximum resistance variation values are 0.0034 and 0.0137 %, which correspond to 0.0082 and 0.061 K temperature shift for the rectangular and circular sensors, respectively. The ΔT/T (%) of rectangular and circular sensors is performed with the magnetic field up to 6T in the temperature range of 10–100 K, and they are within the range of ?19.84 to 0.137 and ?2.18 to 11.33 for rectangular and circular sensors,respectively. The impedance test shows that the sensors have the same electric properties under direct current and alternating current condition.     

一种新型方位传感器

简述了二次谐波法磁通门磁强计的工作原理。以高导磁材料坡莫合金丝作探头铁芯 ,试制了一种以正交的双轴磁通门磁强计为基本结构的摆式航向传感器。该传感器体积小 ,分辨率高 ,精度达到 0 .2°。     

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.     

Electroplating a magnetic core for micro fluxgate sensor

A square-ring shaped micro fluxgate sensor, which was designed for measuring two axes weak magnetic field at the same time, was fabricated using MEMS technologies. To get better magnetic properties, Ni/Fe permalloy was selected to be the materials of magnetic core which was fabricated by DC-electroplating method with several micron thickness. Saccharine was added into the electrolyte to reduce the internal stress, and its influence on magnetic properties was studied. The results show that magnetic properties are related to the crystalline phase transition in the deposition which varied with saccharine content. With 3 g/L saccharine in the electrolyte, a film with low coercive force and high saturation magnetization relatively was obtained and some characters of the sensor were also discussed in the paper.     

新型环形同点单铁芯双分量磁通门传感器

双分量磁通门传感器在金属磁记忆检测中得到广泛使用,且使用的双分量磁通门传感器为双铁芯式跑道型设计的磁通门传感器。由于传感器中的双铁芯磁参数不一致、铁芯不闭合的原因,产生变压器效应,形成了测量噪声。双分量磁通门通常由两个磁通门传感器平行放置而成。因此,由于传感器铁芯参数,线圈参数不可能完全一致所造成的传感器之间的一致性差,而且双分量或多分量磁通门传感器存在着几何中心不重合的问题。本文研究设计了新型双分量磁通门传感器,采用环形铁芯设计,直接应用单铁芯调理双方向的磁通门信号,改善了双分量传感器的一致性差、几何中心不同点的问题,有效的抑制了变压器噪声,提高了磁通门传感器的测量中的测量准确度,减少了测量误差。     

一种三端式磁通门传感器激磁电路设计

磁通门传感器是目前微弱磁场检测中较为理想的测试元件,具有高灵敏度、高精度和良好的稳定性等优点;在分析了三端式磁通门传感器的数学模型的基础上,介绍了其工作原理,即需要激励源、传感器和检测电路共同作用才可以构成完整的测量系统;同时,设计了一种三端式磁通门传感器的激磁电路,其激励电压幅值为5V,频率为5kHz;结果表明,该信号频率和幅值比较稳定,可以作为磁通门传感器的激磁信号。     

地磁相对记录用低噪声磁通门磁力仪

针对地磁相对记录要求观测仪器具有高分辨力、低噪声和长期稳定性的特点,抑制外界温度对传感器输出的影响,获得较低的温度系数,研制的磁通门传感器采用高导磁率坡莫合金作为磁芯材料,激励线圈直接缠绕在高塑性、较高持久蠕变强度的环形合金骨架上,感应线圈和补偿线圈缠绕在低温度系数的玻璃钢骨架上.采用交变模拟信号处理电路、深度负反馈网...     

无线传感器网络中基于分层的非均衡分簇算法

降低网络能量消耗、延长网络寿命是无线传感器网络设计的重要目标,分簇是实现该目标的主要方法之一。针对矩形传感器网络,提出一种基于分层的非均衡分簇算法。算法根据节点的能量消耗情况计算出了每层的宽度,可以有效实现网络的能耗均衡。将非均衡分簇算法与LEACH协议进行了比较,仿真实验表明:基于分层的非均衡分簇算法可以更好地实现能耗均衡,能有效延长网络的寿命。     

Novel sensor design methodology for measurements of the complex solar wind–magnetospheric–ionospheric system

This paper describes the results of an applied novel design methodology for engineering optimised macroscale fluxgate sensors for low-power consumption. The study is used in conjunction with the development of a new fully digital system measuring the Earth’s magnetic field and extracting the necessary parameters for measuring the complex solar wind–magnetospheric–ionospheric system. The results are of interest to the aerospace and defence industries, since macroscale fluxgate sensors exist in airborne and spaceborne systems for many decades. Lowering power consumption is followed by simplification of the accompanying electronic circuits.