共查询到19条相似文献,搜索用时 125 毫秒
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简单分析了InSb磁敏电阻的工作原理,讨论了利用偏置磁场作用于半桥磁敏电阻构成转动速度及位移传感器的测试原理;针对半导体材料对温度十分敏感的特点,提出了利用浮动零点跟踪技术测试齿轮转速的方法,并对其优缺点进行了讨论。 相似文献
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采用溶胶-凝胶(sol-gel)法制备了名义组分为La0.67Sr0.33-xAgrMnO3(x=0.15、0.20)的多晶样品,发现用Ag部分替代Sr后样品的室温磁电阻比替代前明显增大。在1.8T下,La0.67Sr0.18Ag0.15MnO3样品的磁电阻在330K出现峰值,其峰值为35%;对于La0.67Sr0.13Ag0.2 MnO3样品,磁电阻峰值为26%.且峰的宽度较大,在290~315K之间的磁电阻随着温度变化不大.因此显著提高了室温时样品的磁电阻和磁电阻的温度稳定性,另外.还提高了样品的磁场灵敏度。这对磁电阻的应用有很大意义。 相似文献
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对几种C/C复合材料在不同的测试位向(指外加磁场与材料某特定表面的夹角)下的磁电阻效应进行了研究。研究结果表明,C/C复合材料不同位向下的磁电阻大小不同,且不同结构、不同处理工艺的材料出现最大磁电阻的位向不同;已石墨化的材料各位向磁电阻均呈正值,未石墨化材料各位向的磁电阻为负值,但它们的绝对值都随测试温度的增高而线性降低;温度升高到一定值,一些材料的磁电阻为0不再变化;外磁场一定时,对同一材料各位向下磁电阻-温度曲线进行回归,所得回归方程斜率项相同,截距项不同;将各位向磁电阻排序发现,不同工艺和结构的材料位向序列不同;外加磁场强度的改变,只改变各位向磁电阻的大小,不影响位向序列。 相似文献
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《中国测试》2016,(9):1-5
对试样液氮脆断后进行扫描电镜观察是研究材料微观结构的常用方法,但应用于磁性羟基铁粉填充的磁敏弹性体试样时,却很难获得理想效果。通过对橡胶高分子结晶现象和低温脆断理论的分析,揭示脆断截面无法形成裸露的羟基铁粉链的机理;提出机械切割和抛光相结合的截面处理方法,得到的样品截面可满足扫描电镜对磁敏弹性体表面微结构的表征要求。通过对扫描电镜工作原理和成像理论的分析,阐述磁性材料产生的杂散磁场与扫描电镜磁透镜的磁场、入射电子束、收集器电压产生的耦合作用。这种耦合作用使在样品表面按一定时间和空间顺序做光栅式逐点扫描的入射电子束发生畸变,改变磁敏弹性体发射的二次电子的运行轨迹,使二次电子收集器收集效果变弱,降低图像质量。根据绝缘电阻测试得到不同体积分数羟基铁粉的磁敏弹性体的电导率,确定金属离子真空溅射和粘贴导电胶的试样处理方法。提出磁敏弹性体样品的退磁方案,并得到理想的微观形貌图像。 相似文献
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为实现微型化、低功耗、低成本和高灵敏度的磁传感器,提出了一种基于微型磁扭摆结构的磁传感器,并利用对角度变化非常敏感的差分电容检测技术对磁扭摆的扭转角度进行检测.设计的磁传感器包括微扭摆结构、磁性敏感薄膜和差分检测电容等部分.分析了器件的磁敏感原理和电容检测原理,给出了器件的结构参数和综合设计考虑.利用体硅加工工艺成功制作出了磁传感器样品,并进行了实验测试.测试结果表明磁传感器有良好的线性度和重复性,其磁场检测的电容灵敏度可达到0.2fF/Gauss.根据对磁传感器的热噪声分析,可得到磁传感器最小可分辨的磁场为6.72μT.该磁传感器结构简凑、工艺简单,无需电流激励,大大降低了磁传感器功耗. 相似文献
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A novel multiplexed sensing scheme based on the measurement of the magnetic susceptibility of the affinity captured target molecules on magnetic nanoparticles in liquid suspension is proposed. The AC magnetic susceptibility provides a measurement of Brownian relaxation behavior of biomolecules bound to magnetic nanoparticles (MNPs) that is related to its hydrodynamic size. A room temperature, compact AC susceptometer is designed and developed to measure complex AC magnetic susceptibility of such magnetic nanoparticles. The AC susceptometer exhibits high sensitivity in magnetic fields as low as 10 μT for 1 mg ml(-1) concentration and 5 μl volume, and is fully software programmable. The capability of biological sensing using the proposed scheme has been demonstrated in proof of principle using the binding of biotinylated horseradish peroxidase (HRP) to streptavidin-coated MNPs. The proposed technique and instrument are readily compatible with lab-on-chip applications for point-of-care medical applications. 相似文献
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A magnetic field sensing system based on V-shaped groove filled with magnetic fluids is developed in this work. The propagation direction of the emergent light after the V-shaped groove (or the position of the emergent light on the detecting plane) is related to the strength of the externally applied magnetic field. The analytical expressions for the sensing system are derived in detail. The sensitivity and other sensing properties of the sensing system are investigated numerically and experimentally. The sensing mechanism is analyzed and ascribed to the magnetically tunable refractive index of magnetic fluids. 相似文献
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A novel magneto-optic sensor with electrically adjustable sensitivity is proposed that is based on the approximate multiplication correlation between the linear electro-optic phase retardation and the Faraday magneto-optic rotation angle in a single bismuth germanate crystal. The measurement sensitivity and its temperature stability, linear and monotonic measurement ranges of the proposed sensor can be controlled in real time by adjusting the modulating voltage applied to the sensing crystal. In particular, the proposed sensor can be used for the precise measurement of dc magnetic field or dc current. The basic sensing performance is theoretically analyzed and experimentally demonstrated by dc current measurement. 相似文献
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传感器温漂对磁悬浮转子控制精度的影响 总被引:1,自引:1,他引:0
传感器温漂对磁悬浮转子的控制精度有很大的影响.磁悬浮转子在运转时有较大的温升.磁悬浮转子的结构设计对其工作温度的高低及其分布有很大影响.本文研究了磁悬浮转子实际工作温度场的不均匀性,对涡流传感器的温度特性进行了实验测试,对传感器的布置形式对磁悬浮转子精度的影响进行了分析.研究了磁悬浮转子结构形式、结构参数、传感器的个数及其测试方式等对磁悬浮转子控制精度的影响程度和变化规律.在上述研究的基础上得出了减少传感器温漂对磁悬浮转子控制精度影响的结构设计原则. 相似文献
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O. A. Mironov S. Zherlitsyn M. Uhlarz Y. Skourski T. Palewski J. Wosnitza 《Journal of Low Temperature Physics》2010,159(1-2):315-318
Microminiature Hall probes (MHP) may be used as magnetic field transducers, with virtually no change of sensitivity with temperature, for applications at room and cryogenic temperatures. The probes have a nominal active sensing area from 90×90 μm down to 20×20 μm and are based on Sn-doped n-InSb/i-GaAs MBE-grown heterostructures. MHPs were intensively tested in static (up to 14 T) and pulsed magnetic fields and shown to be appropriate for various applications in the temperature range 2–300 K and in pulsed magnetic fields up to 87 T. The latest version of these probes, with overall cross-section thickness-width dimensions of 150×750 μm, are the smallest encapsulated Hall probes currently available and can be placed in areas not previously accessible to commercial packaged or unpackaged sensors. 相似文献
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Changjin Wen 《Journal of Modern Optics》2013,60(8):762-770
Effects of the metal coatings on the fiber Bragg grating (FBG) temperature sensing characteristics were simulated and experimentally investigated. Temperature sensitivity of the coated FBG as a function of the coating material properties was simulated using MATLAB software based on the temperature sensing model. The simulation results show that the elastic modulus, Poisson’s ratio, thermal expansion coefficient and coating thickness of the coatings have noticeable impacts on the sensing characteristics of the coated FBG. It is noted that (i) there is an extreme value for the influence of the elastic modulus on temperature sensitivity; (ii) temperature sensitivity increases with the increase of Poisson’s ratio and thermal expansion coefficient; (iii) with the increase of the coating thickness, the temperature sensitivity increases first then reaches a plateau asymptotically. To validate the simulation results, several FBGs were coated with copper, nickel, cobalt, copper–zinc, and Ni–ZrO2, and subsequently the associated temperature sensitivities were measured using a network analyzer as well as a water bath. The results show that the simulation results agree well with that of the experiments, with the errors up to 5.49%. 相似文献