Highly Sensitive Fiber-Optic Faraday-Effect Magnetic Field Sensor Based on Yttrium Iron Garnet

The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulatein the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity .The sensor system exhibited a noise-equivalent field of 8 pT/√Hz and a 3 dB bandwidth of ～10 MHz.

Field-assisted tunneling enabled pressure-sensitive composites/sensors for smart concrete structures

Spiky spherical nickel powder with sharp nano-tips on its surface is a kind of excellent fillers for developing pressure-sensitive cement-based composites/sensors for traffic detection,structural health monitoring,and border and military security.The sharp nano-tips on the surface of spiky spherical nickel particles can induce field emission and tunneling effects,which leads to the ultrahigh pressure-sensitive responses of the cement-based composites.In this paper,we systematically introduce research on nanotip-induced ultrahigh pressure-sensitive cement-based composites/sensors,with attentions to their pressure-sensitive property and sensing mechanism,pressure-sensitive characteristic model,and smart structure system for traffic detection.

Engineering high-performance dielectric chiral shells with enhanced chiral fields for sensitive chiral biosensor

Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral biosensors.However,the intrinsic Ohmic loss in surface plasmonic resonance has limited their practical use,resulting in large light dissipation and weak chiroptical resonance.Here,we report on the development of high-performance dielectric chiral shells(DCS)through a two-step Si deposition process on a self-assembled microsphere monolayer.The form DCS sample completely oyercomes the cancelation effect originated from the disorder property of the micro-sphere monolayer in macroscale,and at a wavelength of approximately 710 nm,the measured optimal chiral signal(g-factor)and transmittance can reach up to 0.7 and 0.3,respectively.The strong chiroptical effect comes from the asymmetric circular displacement currents(i.e.,magnetic modes)enabled by the specific shell geometry.The chiral shell geometry,electromagnetic properties,sensor sensitivity of chiral molecules and figure of merit are systematically investigated.The DCSs demonstrate highly sensitive detection of chiral biomolecules owing to their easily accessible geometry and enhanced uniform chiral field.

Fabrication and characteristics of magnetic field sensors based on nano-polysilicon thin-film transistors

A magnetic field sensor based on nano-polysilicon thin films transistors(TFTs) with Hall probes is proposed.The magnetic field sensors are fabricated on <100> orientation high resistivity(ρ>500Ω·cm) silicon substrates by using CMOS technology,which adopt nano-polysilicon thin films with thicknesses of 90 nm and heterojunction interfaces between the nano-polysilicon thin films and the high resistivity silicon substrates as the sensing layers.The experimental results show that when V_(DS) = 5.0 V,the magnetic sensitivities of magnetic field sensors based on nano-polysilicon TFTs with length-width ratios of 160μm/80μm,320μm/80μm and 480μm/80μm are 78 mV/T,55 mV/T and 34 mV/T,respectively.Under the same conditions,the magnetic sensitivity of the obtained magnetic field sensor is significantly improved in comparison with a Hall magnetic field sensor adopting silicon as the sensing layers.

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance （SPR） biosensors, novel highly sensitive SPR biosensors with Au nanopartieles and nanogratings enhancement have been proposed recently. But in practice, these structures have obvious disadvantages. In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parame- ters on the performance is investigated by using rigorous coupled wave analysis （RCWA）. Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters. The results indicate that significant sensitivity increase is associated with localized surface plasmons （LSPs） excitation mediated by nanoholes. Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves＇ width are obtained simultaneously under optimized structural parameters.

Design and Fabrication of Magnetic Sensor Based on Giant Magneto-Impedance Effect

A large giant magneto-impedance effect was observed in CoFeSiB amorphous ribbon which was treated with the longitudinal field annealing in an atmosphere of Ar for one hour at 10-3 T and 400 ℃. The maximum magneto-impedance ratio is 475% and magnetic sensitivity of about 120%/Oe (1 Oe=80 A/m) at 20MHz, which is helpful to improve the sensitivity of magnetic sensor. The performances of the sensor were carefully studied in open-loop and closed-loop with negative feedback. The full measurement range of the magnetic field detection is 1.7-4 Oe presently, and the sensitivity achieves 176 mV/Oe. The sensor with negative feedback shows excellent linearity and good stability. The designed magnetic sensor can be applied in geomagnetic field measurement.

三维霍尔开关型传感器

霍尔传感器由于自身的高失调电压和低磁场灵敏度限制了应用,基于SMIC 180 nm互补金属氧化物半导体(CMOS)工艺,设计了一种阈值可调三维霍尔开关型传感器。在霍尔传感器的信号处理电路中,使用四相旋转电流法和相关双采样保持技术对霍尔器件的失调电压进行消除;设计了一种阈值可调电路,实现多种情况的应用;通过失调消除电路的处理,降低了失调。传感器的工作电压为3.3 V,工作电流为7 mA,信号处理电路对微弱的霍尔信号实现了放大,最终输出表示开关状态的数字信号。

金属氧化物pH传感器的研究进展

围绕近年来金属氧化物pH传感器的相关研究,对其传感机理进行了概述,对不同类型金属氧化物pH传感器的研究进展进行了介绍,根据二氧化钌、二氧化铱、五氧化二钽等金属氧化物的特性,分析其作为pH敏感电极的优点和不足,重点分析了4种pH传感器(电位型、电导型、离子敏感场效应管型和外延栅极场效应管型)的制备工艺、工作原理、灵敏度和响应时间,并总结了针对不同应用最适宜的金属氧化物pH传感器类型。最后,对金属氧化物pH传感器面临的问题进行了概述,展望了其未来的发展方向。

一种灵敏度漂移自补偿型MEMS电场传感器

针对温度和应力变化带来的电场传感器灵敏度漂移和测量误差问题,该文提出一种具有灵敏度漂移自补偿功能的微机电系统(MEMS)谐振式电场传感器。传感器结构中,感应电极用于测量外部电场,参考电极用于监测可动结构振动信息;基于振动相位和锁相环技术实现传感器谐振频率自动跟踪,利用参考电极输出信号对感应电极输出信号进行实时补偿,提高传感器灵敏度的稳定性。该文开展了敏感结构设计和理论分析,研制出传感器样机,并进行了样机标定测试。测试结果表明,在±18 kV/m电场范围内,传感器线性度达到0.21%,3个往返行程总不确定度达到1.34%;在–40℃~70℃温度范围内,灵敏度相对漂移量小于3.0%,具有良好的灵敏度漂移自补偿效果。

基于MSE/PVDF复合结构转速传感器的研究

磁敏弹性体(MSE)是一种具有优良磁响应特性的磁敏材料,在磁场作用下将产生垂直其表面的磁致法向力,结合聚偏氟乙烯(PVDF)的正压电效应,针对转速检测提出一种结合两者特性的转速传感器,在敏感单元中设计由MSE与PVDF压电单元组成复合结构,通过复合结构感知磁场激励以实现转速检测,并从微观与宏观层面分析了检测机理,采用自建测试系统确立了磁致法向力与磁场间的关系,PVDF的动态形变响应及传感器的输出特性。结果表明:以复合结构为核心的敏感单元对测试转速的磁场激励表现出稳定的电压峰值响应,并能够实现对中高转速的准确检测。

一种MEMS电场传感器宽频带电场检测方法

基于MEMS(微电子机械系统)技术的微型电场传感器凭借其体积小、功耗低、可批量化制造等优点,在诸多领域得到广泛应用。MEMS电场传感器可用于静电场与交流电场检测,但目前存在电场检测频率范围较窄、测量不同频率电场灵敏度不一致的问题。对此,根据对传感器输出信号的系统性分析,提出了一种适用于宽频域电场检测的方法。理论上,在不考虑放大电路带宽限制和信号饱和的情况下,该方法检测的电场频率没有上限,并且对不同频率电场的检测灵敏度一致。实验结果显示:用该方法检测0~7 kHz频率范围内的电场,具有良好的线性度和准确度,传感器的灵敏度保持了很好的一致性,验证了该方法的合理性。

铌酸锂晶体结构对电场传感器灵敏度影响分析

铌酸锂晶体光学电场传感器为全介质结构,具有宽带宽、对被测电场干扰小的优点,但其灵敏度较低。因此,分析了晶体几何尺寸对传感器灵敏度的影响机理,得出通过增加沿外加电场方向的晶体尺寸同时减少晶体横截面上沿外加电场垂直方向的晶体尺寸来提高传感器的灵敏度。使用COMSOL仿真分析了铌酸锂晶体不同厚度、宽度、长度对晶体内部电场强度的影响,得出晶体厚度从15 mm减小到3 mm和宽度从3 mm增加到22 mm时,晶体内部电场强度分别提高约5.1倍和12.3倍;晶体长度从15 mm变化到55 mm时,晶体内部的电场强度变化仅约为5%。设计并研制出晶体尺寸分别为3 mm×3 mm×42.2 mm (x×y×z),3 mm×6 mm×42.2 mm (x×y×z),6 mm×6 mm×42.2 mm(x×y×z)的三只铌酸锂晶体电场传感器,并搭建工频电场测试平台,测试得出三只电场传感器的灵敏度分别为0.243 mV/(kV·m^(-1))、0.758 mV/(kV·m^(-1))、0.150 mV/(kV·m^(-1))。当晶体厚度和长度一定且晶体宽度从3 mm增加到6 mm时,传感器灵敏度提高3倍。当晶体宽度和长度一定且晶体厚度从6 mm减小到3 mm时,传感器灵敏度提高5倍。结合仿真与实验结果得出:在晶体长度一定时,可以通过设计使用宽度更宽、厚度更薄的晶体,研制出高灵敏度的电场传感器。

氧化钛栅介质离子敏场效应管pH传感器的研制

为了满足微量溶液的检测需求以及解决部分pH传感器灵产品敏度低、尺寸较大以及抗干扰性差的问题,研制了一种氧化钛(TiO_(2))栅介质离子敏场效应管pH传感器。该传感器的沟道层为铟镓锌氧化物(InGaZnO)薄膜,顶栅介质为氧化钛(TiO_(2))薄膜,源极和漏极均为金属铝(Al)薄膜;InGaZnO薄膜和TiO_(2)薄膜均由射频磁控溅射工艺制成,Al薄膜由电子束蒸发沉积工艺制成,3种薄膜材料均通过光刻、刻蚀工艺图形化。传感器具有体积小、灵敏度高、抗干扰性强的优点,尺寸仅为10 mm×15 mm,在室温(25±1)℃条件下,用半导体参数测试仪测得器件在不同pH值(4~10)溶液中的平均灵敏度为63.25 mV/pH,在K^(+)、Cl^(-)、Na^(+)、SO_(4)^(2-)离子干扰下的电压漂移量为相同浓度H^(+)离子干扰下的3%,满足当前生物医学、食品加工等领域的pH值检测需求。

多物理场下压力传感器失效分析方法

由于电力场景的复杂应用环境,应用于其中的压力传感器会面临温度,压力以及电场等多物理场的同时作用的考验,进而导致传感器失效。为分析压力传感器的失效机理,本文首先分析压力传感器的工作原理并基于此设计仿真,以获取压力传感器材料的屈服断裂特性;接下来基于有限元法对其进行力热电多物理场仿真分析,获取传感器在-50℃,20℃,40℃,60℃时和200kPa恒压下的输出电压,其中输出电压即代表着传感器灵敏度。仿真结果表明随着温度的升高,压力传感器的输出电压也随之升高,因此温度的变化会影响传感器的灵敏度。

电容层析成像系统传感器敏感特性分析及比较

电容层析成像传感器的敏感场受多相流介质分布的影响,软场特性给图像重建带来很大困难,为了提高重建图像质量,对敏感场分布进行分析是非常必要的。现以8电极油水两相流电容层析成像系统为研究对象,采用有限元仿真的方法,通过用三角形和四边形两种不同剖分形式对电容敏感场的分析和比较、计算机仿真及实验分析,结果表明利用不等间距的剖分形式可以得到较好的仿真结果,具有较高的精度。

电容层析成像传感器场域剖分及图像重建算法

电容层析成像传感器的敏感场受多相流介质分布的影响,软场特性给图像重建带来很大困难,为了提高重建图像质 量,对敏感场分布进行分析是非常必要的。采用有限元法,通过对敏感机理的分析,提出一种利用不等间距的场域剖分方法, 对敏感场分布进行计算机仿真,依据敏感场计算的数据及测量结果,提出了基于遗传算法的图像重建算法。实验证明有限元 模型是正确的,说明利用不等间距的剖分形式可以得到较好的仿真结果,重建的图像具有较高的精度。

电容层析成像传感器软场性能分析

电容层析成像传感器的敏感场是软场，受被测介质分布的影响·以基于有限元分析的灵敏度快速计算法为工具，通过多种介质分布下灵敏度分布的计算与比较，研究了传感器的软场性能·结果表明，即便对于介电常数差异较小的气／ 油两相流，不同的电介质分布亦可导致灵敏度值有正、负百分之几十的变化·各处灵敏度变化不仅与管内介质分布有关，还与该点在敏感场中所处的位置有关·

电容层析成像系统径向电极对传感器性能及敏感场分布的影响

电容层析成像系统传感器的敏感场分布受多相流介质分布的影响,软场特性给图像重建带来很大困难。该文以8电极油水两相流电容层析成像为研究对象,采用有限元仿真的方法,分析了径向电极及其嵌入尺寸对电容层析成像系统电容值及敏感场分布的影响。通过仿真分析,确定了径向电极的嵌入尺寸,从而能够在缩小测量电容值的动态变化范围,减轻数据采集电路设计难度的同时,提高电容响应的灵敏度,改善传感器敏感场的分布,提高电容层析成像系统的性能。