三维力柔性触觉传感器电极研究与实验

为了实现机器人智能皮肤对三维力的探测,基于炭黑/碳纳米管/硅橡胶的表面压阻效应,设计了2种不同排布的对称结构的四叉指电极三维力柔性触觉传感器.理论分析了这2种三维力传感器的工作原理,并对这2种结构的传感器进行了量程、灵敏度、线性度等实验对比,实验证明四电极方形排布的传感器在剪切力方向拥有更高的灵敏度和更好的线性度,但量程相对十字形排布的传感器较小。通过三维力实验表明,这2种新型的三维力柔性触觉传感器均具备检测三维力的功能,可在机器人皮肤等实际应用场合,根据工作量程和灵敏度的不同要求来选择传感器结构。     

声表面波在MOA比例单元中的热特性研究

无间隙金属氧化物避雷器(MOA)的在线监测是保证电力系统可靠运行的重要措施,实时获取MOA的在线状态,成为避雷器在线监测的热点.本文在介绍避雷器常用测温方式的基础上,分析声表面波(SAW)温度传感器的测温原理并由此分析了SAW器件应用于避雷器在线监测的可行性,本文利用无线无源SAW温度传感器设计了MOA比例单元温度测量的应用方案,通过比例单元动作负载试验的热特性试验,验证了SAW技术应用于避雷器在线监测的正确性,改进了以往测试方式,提高了测量精度,对应用于MOA在线监测有重要的参考价值.     

GA-BP神经网络对SAW压力传感器测量数据的拟合

随着传感技术的不断发展,出现了越来越多以传感器为基础的无线传感检测系统。这些传感系统需要对采集到的数据进行数据分析。因此,传感器的数据分析对于无线传感系统的精确检测起到至关重要的作用。首先对设计的声表面波(surface acoustic wave, SAW)微压力传感器进行实际测量,利用最小二乘法建立数学模型,对测得的频率变化与对应的载荷力之间的关系进行数据拟合分析。随后,构建BP(back propagation)神经网络模型,通过该方法对已采集的数据进行样本训练并对SAW微压力传感器的输入与输出之间的关系进行预测。最后,使用遗传算法(genetic algorithm, GA)对BP神经网络进行优化。结果表明,经过优化后比优化前的BP神经网络误差减少近45%,从而验证了遗传算法能够优化BP神经网络的可行性。该分析方法对声表面波微压力传感器无线传感检测系统的发展提供了重要的研究依据。     

新型压电式三维力传感器的设计及特性研究

基于压电效应设计了一种新型三维力传感器,分析了传感器原理。根据传感器的结构,推导了传感器的灵敏度、固有频率的计算公式;分析了传感器部件参数对传感器灵敏度与固有频率的影响,通过计算与仿真,得到了影响传感器灵敏度与固有频率的影响因素与规律。计算与仿真结果表明了此计算方法的有效性。     

基于微纳光纤的三光束干涉型电场传感器

光纤电场传感器具有体积小、电气绝缘性能良好等特点,在电气设备状态监测中具有广泛而重要的应用。针对传统基于双光束干涉的电场传感器所存在的灵敏度低、温度稳定性差等技术瓶颈问题,提出一种基于三光束干涉(TBI)的电场传感器。为此介绍了传感器的工作机理,讨论了TBI器件的结构参数对传感器性能的影响规律,给出了具有良好温度稳定性及灵敏度的传感器最优结构设计方法。实验测试结果表明,TBI电场传感器的平均灵敏度约为1.32 V/(kV·cm–1),温度稳定性为2.6 pm/℃,传感器对工频及脉冲电场的响应结果表明:传感器具有较宽的响应频带范围。该研究工作对提升全光纤电场传感器的技术水平、推广其在工程中的实际应用具有重要意义。     

基于 FBG 改进泄压阀的旋叶式压缩机 排气压力感知研究

针对旋叶式压缩机排气压力精准监测难问题,提出了基于光纤布拉格光栅(fiber Bragg grating, FBG)改进泄压阀的旋叶 式压缩机排气压力感知方法。 首先,依据旋叶式压缩机泄压阀结构特点,结合 FBG 传感理论,建立了膜片式压力传感器模型, 揭示了压力与中心波长的映射关系;其次,设计了基于泄压阀的三段式 FBG 压力温度复合传感器,理论分析表明该传感器灵敏 度为 304. 26 pm/ MPa;最后通过仿真实验分析,研究了膜片半径、厚度对传感器灵敏度的影响,得到了最优半径与厚度组合(R = 5 mm, h = 0. 6 mm),实验灵敏度为 330. 78 pm/ MPa,研究对旋叶式压缩机状态监测及功耗控制具有重要的理论和实际工程 价值。     

一种用于绝缘子泄漏电流在线监测的宽频带微电流传感器的特性研究

文中描述了一种宽频带微电流传感器，根据传感器的等效电路模型，针对研制的一种用于绝缘子在线监测的穿芯式宽频带微电流传感器，研究了线圈匝数、杂散电容和负载电阻的变化对通频带宽及灵敏度的影响。通过传感器电子电路的分析和saber仿真发现，在理想情况下，传感器低频下限近似为零，高频上限为无穷大。测试表明：该传感器具有通频带宽、线性度好、灵敏度高、无接触等优点，为高压绝缘在线监测系统提供了一种新的微电流传感器。     

磁通集聚器放大磁场分布及矢量选择特性研究

主要针对T型磁通集聚器结构间隙内轴向放大磁场分布特性以及放大磁场矢量,选择性利用三维有限元静磁特性仿真分析及实验验证的方法进行了一系列的分析研究。结果表明,间隙内放大磁场分布均匀区与结构间隙区域具有相似的截面形状,该均匀区的大小与间隙截面积成正比并与间隙距离成反比。另外,通过仿真和实验验证了集聚器能够放大轴向环境磁场强度,缩小横向磁场强度,具有矢量选择特性。该结论为矢量磁传感器增大灵敏度提供了一定的应用基础。     

声表面波(SAW)传感器断路器触臂安装方式可行性研究

由于高压开关柜过热问题引发的供电安全事故时有发生,然而高压开关柜全部为金属密封结构,其发热导电部位被金属遮挡,常规的红外测温手段无法对其内部情况进行测量,因此在开关柜内部安装在线测温装置成为一种有效手段。声表面波(SAW)测温技术具有无源无线、运行可靠性高、维护工作量小等特点,是目前应用较为广泛的高压开关柜测温技术手段。但是不同厂家生产的SAW传感器安装位置与方式不一,不同的安装方式对测温结果的有效性和系统安全性带来了影响。文中针对声表面波(SAW)传感器手车开关导电臂安装方式的可行性进行了分析和论述。通过工频耐压试验、雷电冲击试验和局部放电检测验证了该安装方式的绝缘安全性能。另外通过对开关柜和手车开关整体做温升试验,从而验证手车开关导电臂安装方式下SAW传感器温度监测数据的准确性、实时性和有效性。     

昆虫电荷特性测量传感器的研究

针对昆虫探测及定位困难的问题,应用静电感应理论,建立了昆虫电荷特性传感器模型,设计制作了高灵敏度的昆虫电荷特性传感器和微电流测量电路;对传感器信号及噪声进行分析计算,并进行了标定试验。结果表明该昆虫电荷特性传感器对匀强电场的灵敏度是0.05 V/m,电荷量灵敏度为0.03 pC,线性度优于2%,可以完成对昆虫电荷量和电荷特性的测量任务,对进一步开展昆虫电荷特性的研究具有重要意义。     

Design and analysis of a novel SAW sensor for civil structural health monitoring

This paper presents a novel surface acoustic wave sensor for civil structural health monitoring. The sensing chip packaged in a shell is composed of two SAW delay line dice. One is utilized to sense the pressure induced by a gauge, and the other is used to sense the surrounding temperature for temperature compensation. Each SAW delay line die consists of an inter-digital transducer and two open grating reflectors. The SAW devices are analyzed by using coupling of modes model. Then, the devices in different parameters are fabricated on a 128°Y-X cut LiNbO₃ substrate by lift-off technique. Finally, a network analyzer is utilized to test the devices. Large signal-to-noise ratio, low loss and clear sharp peaks of the reflection coefficients S₁₁ in frequency and time domain can be observed. The experimental results matched well with the theoretical analysis by the finite element software COMSOL. The IDT finger pairs number, electrodes number of per reflector and acoustic aperture effect the reflection coefficient S₁₁ is discussed in detail.     

A novel electrode‐area‐weighted method of implementing wavelet transform processor with surface acoustic wave device

The objective of this research was to investigate the possibility of a novel electrode‐area‐weighted (EAW) method of implementing wavelet transform processor (WTP) with surface acoustic wave (SAW) device. The motivation for this work was prompted by a diffraction problem of the WTP using SAW device. In this paper, we propose a novel EAW method in order to solve the diffraction problem. When the electrode areas of the EAW wavelet interdigital transducer (IDT) (i.e. the input IDT) are designed according to the envelope areas of the wavelet function, the impulse‐response function of the EAW wavelet IDT is equal to the wavelet function, so that the novel EAW WTP using SAW device can be fabricated. In this study, we also present the diffraction problem, the substrate material, and the electrode number of the output IDT as three key problems, and the solutions to the three key problems are implemented. Copyright © 2016 John Wiley & Sons, Ltd.     

A Novel Wireless Passive Temperature-Pressure SAW-based Sensor

A novel wireless and passive surface acoustic wave (SAW) sensor is developed for measuring temperature and pressure. The sensor has two single-port resonators on a substrate. One resonator, acting as the temperature sensor, is located at the fixed end without pressure deformation, and the other one, acting as the pressure sensor, is located at the free end to detect pressure changes due to substrate deformation. Pressure at the free end bends the cantilever, causing a relative change in the acoustic propagation characteristics of the SAW traveling along the surface of the substrate and a relative change in the resonant frequency of the resulting signal. The temperature acts on the entire substrate, affecting the propagation speed of the SAW on the substrate and directly affecting the resonant frequency characteristic parameters. The temperature and pressure performance of this new antenna-connected sensor is tested by using a network analyzer, a constant temperature heating station, and a force gauge. A temperature sensitivity of 1.5015 kHz/°C and a pressure sensitivity of 10.6 kHz/gf at the ambient temperature have been observed by wireless measurements. This work should result in practical engineering applications for high-temperature devices.     

Surface acoustic wave sensors to detect volatile gases by measuring output phase shift

This paper presents properties of saw acoustic wave (SAW) gas sensors to detect volatile gases such as acetone, methanol, and ethanol by measuring phase shift. A dual-delay-line saw sensors with a center frequency of 100 MHz were fabricated on 128^∘ Y-Z LiNbO₃ piezoelectric substrate. In order to improve sensitivity of SAW sensors, a thin titanium (Ti) film as mass sensitive layer was deposited using e-beam evaporation on the surface of the SAW sensors. In our investigation the response time and sensitivity of SAW sensors were measured. The response time and sensitivity of SAW sensor with thin Ti film were strongly improved because of changing electrical and mechanical properties in the mass sensitive layer. As a result, high sensitivity and fast response time could be achieved by deposition of thin Ti film as mass sensitive layer on the surface of SAW sensor. It can be applied for high performance electronic nose system by assembling an array of different sensors.     

Temperature stability of ZnO thin film SAW device on fused quartz

Surface acoustic wave (SAW) filters for low-frequency (38-65 MHz) applications have been developed using a radio frequency (RF)-magnetron-sputtered ZnO film on fused-quartz substrates. SAW propagation characteristics such as electromechanical coupling coefficient (K/sup 2/), SAW phase velocity (v), insertion loss, and temperature coefficient of delay (TCD) have been measured. The intergidital transducer (IDT)/ZnO/fused-quartz device structure yields almost zero TCD (1 ppm/spl middot//spl deg/C/sup -1/) with 0.316 /spl lambda/ thick ZnO layer (for the device operating at 60 MHz). Alternately, an overlayer of positive TCD material (ZnO itself) has also been deposited on the IDT/ZnO(<0.316 /spl lambda/)/fused-quartz device at a low substrate temperature to reduce the TCD. A modified layered structure consisting of ZnO/IDT/ZnO/fused quartz yields almost zero TCD (-3 ppm/spl middot//spl deg/C/sup -1/) with a 5.3-/spl mu/m-thick ZnO overlayer and a 8.1-/spl mu/m-thick (0.183 /spl lambda/) ZnO bottom layer. Experimentally obtained SAW propagation characteristics have been compared with the theoretical results.     

Effects of rapid thermal annealing on surface acoustic wave ultraviolet sensors using ZnO nanorods grown on AlN/Si structures

In this study, we demonstrate a high sensitivity of surface acoustic wave (SAW) ultraviolet (UV) sensor based on ZnO nanorods (NRs) grown on an aluminum nitride (AlN)/silicon (Si) layered structure. The one-dimensional ZnO NRs act as a high-UV sensing material due to their large surface-to-volume ratio. The fabrication of SAW UV sensor is entirely compatible with micro/nano electromechanical (M/NEMS) process with conventional lithography and synthesized ZnO NRs by hydrothermal method at low temperature. The rapid thermal annealing (RTA) process effectively improved the optical properties of ZnO NRs and the sensitivity of the SAW UV sensors. The resulting SAW UV sensors responded to various UV light intensities, and the RTA-processed samples showed high sensitivity. The SAW UV sensor after RTA treatment at 600 °C showed the highest sensitivity with a 130 kHz frequency shift at a UV light intensity of at 0.6 mW/cm², a 5-fold increase in sensitivity compare with as-grown sample.     

Sensors based on saw resonator with “nontraditional formats” of output signal

It is demonstrated that the sensitivity of sensors based on two-port surface acoustic waves (SAW) resonators increases by a factor of Q (Q-loaded quality factor of the resonator) if the output signal of these sensors is represented in the phase format instead of the conventional frequency format. Practical possibility of use of the SAW gas sensor with phase format of transmitted signal as output signal is demonstrated using procedure of the determination of the water contents in gaseous nitrogen with 386 MHz ST-quartz SAW resonator as an example. It is found that the SAW power affects the sensor response owing to the influence of the SAW intensity on the equilibrium amount of water molecules adsorbed on the resonator surface. Extremely high sensor sensitivity was obtained when using phase format of reflected signal as a sensor output. Using such a format of sensor output we have reliably measured the change of temperature of ST-quartz SAW sensor substrate as small as 0.01^∘C.     

Design and analysis of MEMS piezoresistive rectangular paddle microcantilever based wind speed sensor

Abstract

This paper presents design, simulation and finite element analysis of a wind speed sensor based on MEMS piezoresistive microcantilever. The design is based on the drag force of the wind flow on any structure and employs four piezoresistors in Wheatstone bridge configuration to provide an electrical readout. Two basic structures, diaphragm and cantilever, are designed and simulated for the wind speed range 0–35 m/s using Coventorware 2012. As the magnitude of the force exerted by the wind with a speed of 35 m/s is very small, enhancement in the sensitivity of the sensors involved is a priority and can be achieved by structural variation of the cantilever. The optimized diaphragm structure provides a sensitivity of 0.31007?mV/(m/s)V. This is increased to 0.41612?mV/(m/s)V when utilizing a simple cantilever structure. The piezoresistors are also optimized by varying their dimensions so as to provide maximum sensitivity of 0.47843?mV/(m/s)V. The cantilever structure is optimized for maximum sensitivity by introducing a rectangular paddle at the free end. The optimized sensor is simulated for the range wind speed 0-35 m/s and provides a sensitivity of 1.3156?mV/(m/s)V. MEMS based piezoresistive wind speed sensor has advantages of having a small size, low power consumption and good sensitivity over wide range of operation.