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.     

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.     

Wireless and batteryless SAW sensors,a promising solution for harsh environments

In this paper,general principle of the Surface Acoustic Wave(SAW) sensor in wired and wireless con-figurations will be developed and a review of recent works concerning the field of high temperature applications will be presented.The first part will be devoted to aspects of data transmission and processing.Both configurations of SAW de-vice,delay line and resonator,will be discussed as well as the remote interrogation techniques used to collect and to proc-ess signal.The second part will be devoted to the material aspects.Indeed,knowing that the conventional piezoelectric substrates such as quartz or lithium niobate cannot be used at high temperature,the choice of the material constituting the SAW device(substrate & electrodes) is one of the challenges to face.We will focus our discussion on the Langasite,the current reference for high temperature applications,and on the AlN/Sapphire structure,the very promising alternative for application where the use of high frequency is required.     

声表面波谐振器无源传感信号特性和信号处理方法研究

无源无线声表面波谐振器传感信号是一个低信噪比、瞬态衰减信号,并叠加有激励信号和信道噪声.本文利用信号统计特性,显著地提高信噪比,获取谐振频率所在区间,让激励频率在该区间内取值,使之逼近谐振频率,从而达到检测谐振频率的目的.     

ZnO based surface acoustic wave ultraviolet photo sensor

Ultraviolet (UV) sensor based on ZnO thin film surface acoustic wave (SAW) device is reported. ZnO films were grown using an RF magnetron sputtering technique. SAW devices were made using such ZnO films exhibiting a central frequency at ～41.2 MHz. The SAW UV sensor was fabricated by depositing a 70 nm thin photoconducting ZnO overlayer on the fabricated SAW device. The SAW UV sensor was found to exhibit interesting photoresponse behavior to UV illumination, and a downshift in frequency of ～45 kHz, and a change in insertion loss ～1.1 dB were observed under UV illumination intensity of 19 mW/cm². The changes in the frequency of operation and the insertion loss have been attributed to the acoustoelectric interaction between the photogenerated charge carriers and the potential associated with the acoustic waves. Results show the promise of ZnO for the fabrication of low cost wireless SAW UV sensors.     

声表面波无源无线温度传感器产品研究进展

声表面波（SAW）温度传感器可以实现无线无源检测,满足高温、高压、强电磁辐射和强电磁干扰等恶劣环境下正常工作,属于高水平传感器。首先介绍了应用SAW技术的无源无线温度传感器谐振型和延迟线型2种结构的基本工作原理,着重描述了目前国内外高温和低温SAW无源无线温度传感器的产品性能,对各产品进行了比较和分析,提出了SAW温度传感器询问距离的优化方法。询问距离的优化研究对SAW温度传感器在更广泛领域的应用将有深远意义。     

折线型IDT的SAW微力传感器设计研究

声表面波(SAW)微力传感器易于集成和小型化,无源无线的工作方式,具有极大的应用潜力.将其应用于物体间微间隙压力检测有望实现高灵敏、低功耗的监测水平.针对复杂环境中存在的测量灵敏度问题,设计了一种具有折线形状的叉指换能器(IDT)的SAW微力传感器.采用有限元分析方法(FEM)对其进行了仿真分析和结构参数设计.理论分析...     

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...     

用于传感器的声表面波谐振器耦合模理论研究

本文主要研究声表面波耦合模理论在声表面波谐振器中的应用。本文结合声表面波谐振器的特点，对谐振器表面沉积介质薄膜后引起器件结构参数的变化进行了分析，为研究基于ＳＡＷ谐振器的传感器提供了一种方法。     

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.     

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.     

BST Capacitor Based Tunable Matching Network for SAW Sensors

Surface acoustic wave (SAW) sensors are becoming extremely important in environmental health monitoring by wireless technologies. SAW devices need impedance matching networks at the input and output for efficient power transfer. In this paper, we are presenting the results of tunable matching networks for SAW devices with BST capacitors. We used simple L-matching network implemented with chip inductors and tunable BST capacitors. The characteristics of tunable matching network interfaced to SAW device is simulated using Agilent's ADS simulation tool. The return loss from the SAW devices can be increased and tuned significantly by applying a tuning voltage to the BST capacitors. The SAW device which has been studied is SAW filter.     

声表面波无源无线温度传感系统研究

本文提出了一种单端口声表面波无源无线温度传感系统。该传感系统采用间歇正弦脉冲串信号作为无线激励信号，而反射波是一调幅信号，该调幅信号的包络频率为激励信号频率与声表面波器件固有频率的差，该传感系统提高了遥感的距离并且减小了环境对固有频率测量的影响。     

Filter technologies for wireless base stations

Phenomenal growth in the telecommunication industry in recent years has brought significant advances in filter technology as new communication systems emerged, demanding more stringent filter characteristics. In particular, the growth of the wireless communication industry has spurred tremendous activity in the area of microwave filter miniaturization and has been responsible for many advances made in this field. The filters that are currently being used in wireless base stations can be divided into two main categories: coaxial cavity resonator filters and dielectric resonator (DR) filters. While coaxial cavity filters have limited quality factor (Q) values, they offer the lowest cost design and are still being widely employed, particularly in wide bandwidth applications. With increased demands for high performance wireless systems, dielectric resonator filters are emerging as the baseline design for wireless base stations. Over the next five years, dielectric resonator filters are expected to have a significant share of the overall wireless base station filter market. High-temperature superconductor (HTS) filters are also expected to have a share of this market, particularly for systems, which have very stringent requirements for out-of-band interference. In this article, we begin by reviewing the main filter requirements, highlighting the technologies that are being currently employed. Emerging filter technologies that have the potential to replace the existing technologies are then described.     

基于ZigBee技术低功耗无线温度数据采集及传输

提出一种基于ZigBee无线传感器网络技术的无线温度数据传输设计方案。结合温度参数采集算法,设计了ZigBee低功耗无线温度数据采集及传输网络节点,以标准Pt100实现温度数据采集,采用掌上智能终端PDA以及上位机计算机对接收数据进行分析处理。结果表明,系统可实现在70m范围内实时传送采集到的温度数据,系统功耗〈20mA,时间同步精度较高,工作状态稳定,能够满足工业环境下的温度数据参数的远程监控。     

Bulk acoustic wave RF technology

RF filtering in mobile terminals is dominated by surface acoustic wave (SAW) and bulk acoustic wave (BAW) based filters due to their high performance, small size, and low cost. As compared to SAW filter technology, BAW filter solutions can provide lower insertion loss, better selectivity, higher power handling, higher operation frequency, and better ESD protection. With these advantages, BAW filter technology has been gaining more market share in wireless communication application.     

波导谐振环微带阵列多裂纹检测传感器设计

针对飞行器机翼的大面积壁板等金属结构的多形态裂纹分布难以同时检测、检测精度低等问题,设计了一种互补开口波导谐振环微带阵列多裂纹检测传感器。该传感器群阵列中不同尺寸的互补开口波导谐振环微带传感器能够检测直裂纹、针孔、星型3种裂纹的特征参数。实验结果表明,传感器对3种裂纹的参数变化的最大检测灵敏度达到了150 MHz/mm,传感器可检测出的最小直裂纹尺寸为10 mm×1 mm×0.1 mm。该传感器结合了互补开口谐振环辐射能力强、易于表面共形和基片集成波导低损耗、品质因数高、尺寸小的特性,能够实现对金属材料上多形态裂纹的同时检测,具有灵敏度高、检测范围大等优点。     

基于ANSYS的超声波电动机压电振子动力学参数的提取

从理论上推导了在某一模态下超声波电动机振子的模态参数之间的关系,利用ANSYS软件对超声波电动机压电振子进行数值模拟分析,实现了基于ANSYS的压电振子各动力学参数的提取,从而将复杂的超声波电动机振子模型简化为单自由度的弹簧一质量系统,经与理论计算值对比,结果表明该方法对于获得超声波电动机动力学参数行之有效.     

基于无线传感器网络的绝缘子泄漏电流在线监测系统

将无线传感器网络用于输电线路绝缘子泄漏电流监测与预警系统,分析了其技术特点及系统构成,设计和实现了监测系统中各个组成部分的软、硬件。结合输电线路的结构、布局及监测参数等特点,设计了长链树状无线传感器网络的拓扑结构。针对传感器网络数据传输中的漏斗效应问题,实现了多模层次无线传感器网络构建。解决了输电线路绝缘子泄漏电流在线监测数据传输中的一些关键问题,如利用邻近网络Sink节点进行信道调整的联合传输模型解决网络瓶颈问题等。无线传感器网络的优良特性使及时、准确、低成本的输电线路监测成为可能。     

基于ZigBee的无线智能门禁系统设计

无线传感器网络是随着无线通信和嵌入式计算技术、传感器技术、微机电技术的发展而发展起来的一种新兴的信息获取技术。网络中的节点具有体积小、价格便宜以及低能耗等特点,同时还具备信号采集、数据处理、短距离通信等功能。基于上述的特点,无线传感器网络在军事、环境监测、智能家庭等方面都有着较大的潜在应用价值。提出了一种基于ZigBee无线传输技术的智能门禁系统设计方案并介绍方案的具体实施过程。