基于COMSOL的声表面波器件仿真

声表面波器件在通信、传感、射频识别等领域有着广泛的应用.以有限元方法为基础,利用有限元软件COMSOL对声表面波器件进行了仿真.从器件的模型建立入手,按由浅入深的顺序对无电极压电基片、压电基片表面沉积叉指换能器、叉指换能器表面溅射薄膜、薄膜上负载液体的4种结构进行了仿真分析.仿真研究表明:叉指换能器的电极效应会产生正、反特征频率,并且两种频率都随着叉指电极的敷金比与高度增加而向低频偏移;薄膜厚度的增加同样会导致器件频率向低频变化;当器件负载液体用于液体密度检测时,可通过器件频率变化对液体密度的灵敏程度来对薄膜厚度进行优化.其研究结果可以为声表面波器件的设计制作提供依据.     

Characterization of a Polycrystalline Material with Laser-Excited Nonlinear Surface Acoustic Wave Pulses

High-amplitude nonlinear surface acoustic waves (SAWs) generated by laser pulses were observed in polycrystalline material (stainless steel), and the nonlinear acoustic parameters were evaluated. The velocities of bulk waves and the elastic moduli of the second order were determined by detecting the surface perturbations produced by longitudinal and shear bulk waves (precursors). Consequently, a consistent set of elastic and acoustic constants was obtained by performing all necessary measurements with the same sample using laser excitation and detection techniques.     

A Novel Saw Device in CMOS: Design, Modeling, and Fabrication

The design, finite element modeling, fabrication, and characterization of a novel surface acoustic wave (SAW) delay line for bio/chemical and telecommunication applications in CMOS technology are introduced. A full modeling was carried out. The devices are designed in a standard semiconductor foundry 1.5-mum two-metal two-poly process. A unique maskless postprocessing sequence is designed and completed. The three postprocessing steps are fully compatible with any standard integrated circuit technology such as CMOS. This allows any signal control/processing circuitry to be easily integrated on the same chip. ZnO is used as the piezoelectric material for SAW generation. A thorough characterization and patterning optimization of the sputtered ZnO was carried out. The major novelties that are introduced in the SAW delay line features are the embedded heater elements for temperature control, compensation, and acoustic absorbers that are designed to eliminate edge reflections and minimize triple transit interference that is amplified by edge reflections. Both of these attributes are designed by using CMOS materials without disturbing SAW performance     

Some Applications of Surface Acoustic Wave Sensors

The paper describes the evaluation of thin amorphous magnetic film by using of surface acoustic waves on piezo electric substrate. The obtained experimental data show strong dependence of material parameters on the annealing temperature. The mixed ferromagnetic/SAW devices for electronic applications will be also discussed.     

基于机器学习的声表面波温度传感器快速优化设计

目的 为提高声表面波谐振器(SAWR)性能,制造高性能声表面波(SAW)温度传感器。方法 通过FEM/BEM理论,建立SAW温度传感器精确仿真优化模型,基于此模型对敏感基片的欧拉角进行大步长优化;同时,结合仿真数据并利用多项式回归模型对敏感基片的欧拉角进行小步长快速优化。结果 文中提出的FEM/BEM仿真模型与机器学习相结合优化设计方法不仅能够实现SAWR的精确模拟,而且可大幅提高优化效率。优化结果与实际器件的中心频率相对误差为0.4%,Q值相对误差为1.2%。文中提出的FEM/BEM仿真模型与机器学习相结合优化设计方法与纯FEM/BEM方法相比,单个切型计算速度提高了2 000多倍。结论 所设计的优化系统可用于谐振器敏感基片切型的快速优化设计,可缩短高性能SAW温度传感器的开发周期。     

声表面波器件的研究进展

声表面波器件作为一种新型的电子器件,近年来引起了人们极大的关注,在科学研究领域有了较大的进展,在现代无线通讯领域的应用范围日趋广泛.本文简述了目前国际上出现的声表面波器件的制备方法、性能研究及其应用,展望了其今后的发展趋势.     

声发射传感器表面波灵敏度的比较法校准

声发射传感器的校准是声发射技术的重要课题,基于表面波的比较法校准是声发射传感器校准中的常用方法,其原理简单,校准效率高,适用于声发射传感器的日常校准。本文针对比较法校准,优化了校准中使用的声发射源和声场,构建了完整的声发射传感器比较法校准系统,编写了相应的校准程序,实现了传感器表面波灵敏度的校准,并具有较好的重复性和稳定性。     

LiNbO3声表面波特性及其应用

LiNbO3因其优异的压电性能和声表面波特性被广泛应用于声表面波器件中.着重介绍LiNbO3的压电性能、声表面性能及其薄膜制备技术,对通过不同制备工艺生长出的LiNbO3薄膜的质量和声表面波性能进行了比较,并简要介绍了LiNbO3在声表面波领域应用的新进展.     

声表面波温度传感器抗干扰技术研究

目的设计一种声表面波(SAW)温度传感器抗干扰技术,以提高温度测量的稳定性。方法分析SAW谐振器(SAWR)回波特性,建立SAWR回波信号熵能量模型,发现SAWR回波信号的衰减过程与熵能量的上升过程对应。当回波信号达到噪声水平时,熵能量的单调上升过程消失。为了抑制正弦干扰设计一种改进型自相关算法,利用该算法对信号进行去噪的同时使谐振器回波信号的衰减特性和正弦干扰的等幅特性得到保持。结果根据模拟仿真结果设置了SAWR回波信号的检测阈值(V_(thre)=1),并对该阈值进行了蒙特卡罗仿真实验。仿真结果表明,当信号信噪比大于4dB时,SAWR回波信号的检测率达到86%,而正弦干扰误检率小于0.5%。最后应用该算法对实际的正弦信号和SAWR回波信号进行了检测,得到的误检率接近于0。结论实验结果显示,所设计的算法可以用作声表面波温度传感器的抗干扰技术。     

可调声表面波滤波器的研究进展

随着移动通信产业的迅猛发展,作为通信系统关键器件之一的声表面波滤波器(SAWF)迎来了新的研究热潮.可调SAWF(TSF)因其体积小巧、性能卓越,越来越受到重视.简述了SAWF的原理,介绍了几种主要TSF的结构、性能和特点,展望了其今后的发展趋势.     

新型声表面波气体传感器

介绍了声表面波（SAW）气体传感器的工作原理及器件制作，提出了1种表面波SO2传感器，它采用三乙醇胺（TEA）覆盖薄膜，分辨率可达70×10－9。还讨论了SAW气体传感器的稳定性、可靠性、灵敏度及选择性等问题，并给出了有关的实验结果。     

Spatial Sensitivity Distribution of Surface Acoustic Wave Resonator Sensors

The sensitivity distribution of surface acoustic wave (SAW) resonator sensors is investigated by theoretical and experimental means. It is shown that the sensitivity to mass loading varies strongly across the surface due to the confinement of acoustic energy toward the center of the device. A model is developed for this phenomenon based on the extraction of coupling of modes parameters from a rigorous boundary element method analysis based on a periodic Green's function. As SAW sensors for many applications include a layer covering the electrodes, a new technique is introduced to account for the mechanical interactions with buried electrodes. Using this technique, the sensitivity calculations are found to be in good agreement with measurements. It is also shown that while changes in other parameters influence sensitivity, it is velocity change that most strongly determines overall frequency change     

基于声表面波技术的室内定位系统

针对现有采用接收信号强度RSSI原理的室内定位系统存在的问题,鉴于声表面波技术的无源、受多径效应影响小等优势,搭建了由声表面波定位标签和阅读器构成的室内定位系统.阅读器分时读取3个阅读器天线接收到的定位标签回波信号,与常规的室内定位硬件系统采用3个信号接收机相比,大幅度降低了成本.标定了系统的信号强度与距离之间的关系,采用基于RSSI原理的三边定位算法测试了系统的定位性能,其有效定位范围为1.6 m×1.6 m,定位精度为13 cm.     

新型多层结构压敏-电容双功能陶瓷元件的制备与性能研究

本文选择ZnO和Pb(Mg1/3Nb2/3)O4为基体材料,利用轧膜技术制备了多层片式结构的压敏-电容双功能陶瓷元件.通过工艺因素和SEM微观形貌分析,研究了ZnO基压敏材料和Pb(Mg1/3Nb2/3)O3基电容材料的制备过程、热行为匹配性、微观结构等在制备多层结构中的作用.以仿独石工艺形成了具有压敏-电容双功能的陶瓷元件,获得了降低元件压敏电压和提高其电容量的有效途径,为此类材料的应用打下研究基础.     

基于声表面波传感技术的微液滴检测方法

为了提高声表面波(SAW)技术用于微液滴体积测量的精度,提出了一种差分面积拟合法.根据声表面波信号的特点分析了差分面积拟合法的合理性,在自行研制的声表面波液滴体积检测系统上对该方法的应用进行了验证.采用两种黏性不同的微液滴,分别为5～9μL的微水滴和微油滴进行了测量.对测得的信号分别采用曲线峰值法和差分面积拟合法与微液滴大小进行回归.实验结果表明,采用差分面积拟合法进行回归得到的模型的相关系数相比采用峰值法提高了4%以上,同时对两种微液滴的预测均方根误差(RMSEP)减小了37%以上,从而证明了该方法的有效性.     

基于SVD-Rife算法的声表面波应变传感器高精度解调方法设计

目的提出一种可用于储运材料表面应变检测的声表面波(SAW)检测方法,设计一种基于SVD-Rife算法的高精度SAW应变传感器解调方法。方法利用SVD方法实现对SAW谐振器回波信号去噪,以提高解调精度;基于Rife算法设计一种谱细分估计方法,该方法可减少系统的硬件要求,提高谱估计精度。结果对设计的解调方法进行了仿真和实验,仿真结果表明估计方差得到改善,最大误差为0.25 kHz。对提出的SAW应变传感器进行了实验,得到的传感器线性度为1.45%,重复性为1.09%,与传统的解调方法相比线性度得到改善。结论实验结果显示所设计的解调方法可用于储运材料表面应变的检测。     

Surface Wave Utility in Composite Material Characterization

Abstract

A surface wave velocity measurement technique is used to supply supporting measurements in the computation of elastic constants for practical nondestructive evaluation of composite materials. Theoretical modeling work is carried out to illustrate the surface wave velocity changes as a function of angle with respect to the axes along the fibers of a unidirectional graphite epoxy composite material for a variety of different problems, including porosity (PC) changes, fiber volume fraction (FF) changes, and delamination. Experiments are conducted on two unidirectional reinforced composites and a (0–90)_s cross ply graphite epoxy laminate to illustrate the surface wave velocity measurements and the inverse computation procedure for evaluation of the stiffness coefficients. Variations of the feature values in the stiffness matrix are also discussed for inhomogeneities, delaminations through cracking, and large defects.