复杂声表面波滤波器进化设计

传统的复杂声表面波滤波器设计方法繁杂,迫切需要简炼的复杂声表面波滤波器设计技术,提出了一种新的声表面波滤波器设计方法,它将变迹的输入和输出叉指换能器进行"分割-求和",以声表面波滤波器中心频率处的插入损耗和旁瓣抑制作为寻优目标,叉指换能器的指条长度作为基因,通过选择、交叉和变异等遗传操作,自动生成复杂声表面波滤波器的输入和输出叉指换能器所有指条长度,进化实例表明,所提出的设计方法能自动、高效地满足所要求设计指标的复杂声表面波滤波器,且具有较强的实用价值.     

抽指加权叉指换能器进化设计

为克服传统方法设计抽指加权叉指换能器的繁杂性,提出了一种全新的抽指加权叉指换能器的设计方法,它模仿生物进化规律,将所设计的抽指加权叉指换能器进行二进制编码,并根据任意给定的目标频率响应曲线和抽指加权叉指换能器的频响特性构造适应度函数,同时考虑抽指加权叉指换能器的指条抽取后的邻近效应,通过排序选择、一点交叉和变异等遗传操作,自动进化出符合任意给定频率响应特性的抽指加权换能器.进化实验结果表明,该设计方法正确有效、实用性强.     

小波变换用于钢丝绳断丝检测的研究

本文采用漏磁场探伤方法对钢丝绳断丝进行检测,该方法的原理是利用励磁磁场和缺陷(即钢丝断丝处)相互作用产生的漏磁场来检测钢丝绳断丝,并且利用霍尔元件能够准确地获取漏磁场信号.首次把声表面波式小波变换的重构器件应用于钢丝绳断丝检测中.发现声表面波器件的发射叉指换能器和接收叉指换能器的指条重叠包络均按照小波函数(如Morlet小波)包络设计时,从而得到声表面波器件的发射叉指换能器和接收叉指换能器的脉冲响应函数均等于小波函数,所以制作出了声表面波式小波变换的重构器件.该器件是一带通滤波器,其相对带宽是1.1%,所以该器件可有效滤除干扰信号.     

基于电路仿真技术异型声表面波器件特性分析

为了能够采用EDA工具设计含声表面波器件的电子系统,本文研究了应用EDA工具仿真声表面波器件特性的方法.它以叉指换能器一个周期段的Mason等效电路模型为基础,根据电网络理论将Mason等效电路模型中的复阻抗采用LC串并联网络来等效,LC网络中的各L、C值采用进化方法确定,使得串并联网络的等效阻抗和Mason等效电路中的阻抗特性误差最小,并以子电路的形式由自行研制的异型声表面波器件各叉指换能器的等效电路调用,异型声表面波器件幅度特性仿真结果与实测结果在中心频率处插入损耗基本相符.     

基于声表面波技术的微流体混合及仿真

报道了在微流系统中使用基于叉指聚焦换能器的声表面波的一种有效方法.利用lift-off和软光刻技术在铌酸锂( LiNbO3)压电单晶片基底上制作器件.使用有限元分析软件COMSOL Multiphysics分别模拟聚焦叉指电极和平行叉指电极两种声表面波的形成和分布.通过与相同条件下的平行叉指电极比较,说明聚焦叉指电极可...     

一种新的纸基微流开关及其活跃方法

提出了一种新的、基于声表面波的纸基微流开关。通过软光刻技术制作内含两个微孔的聚二甲基硅氧烷(PDMS)微架,其上固定经折叠、长度可变的纸通道。PDMS微架贴附于压电基片之上,并在待连接的两微通道之下方,折叠纸通道最低端离压电基片间距为2 mm。压电基片上采用微电子工艺光刻一对叉指换能器和反射栅。当足够强度的电信号加到叉指换能器对时,激发两相向声表面波,使得压电基片上微流体输运到折叠纸通道,改变其长度,连接其上待连通的两纸基微通道,完成开关功能。对可编程微流器件提供了一种新的编程和开关控制方法。     

基于压电基片微液滴间隙式驱动研究

连续的声辐射力驱动方式难以在平面内精确操控微流体,报道了单步驱动微流体及其在平面中位置确定的方法.在128°-YX LiNbO3上制作中心频率27.7 MHz叉指换能器组,经方波调制的载波信号加到叉指换能器激发间隙性声表面波,以单步驱动其声路径上的微液滴.垂直方向叉指换能器组确定微液滴平面上位置.采用水和0.1 g/mL的NaCl溶液进行间隙性驱动实验,结果表明,在载波强度达到一定幅度时,微液滴运动速度随调制信号频率增大而减少;当调制信号频率一定时,声路径上微液滴运动速度随载波幅度增大而增大.     

基于两相向声表面波快速富集悬液中微粒

为提高生化分析灵敏度,提出了一种快速富集悬液中微粒的新方法.它在127.68°旋转Y切割X传播方向的LiNbO3基片上采用微电子工艺制作了2×2叉指换能器阵列,在该叉指换能器阵列的一对对角叉指换能器上同时加经功率放大器放大后的RF信号,以激发两相向声表面波,采用微量进样器将待富集的微流体(微液滴)进样到两相向传播的声路径上,微液滴中的微粒在该两相向的声表面波作用下快速向心富集.淀粉溶液微液滴富集实验结果表明,两相向声表面波作用下,10秒内实现微液滴中淀粉微粒的快速富集.     

声表面波传感器Q值改善的理论与实验分析

用P矩阵方法分析带变迹叉指换能器(IDT)和倾斜金属反射栅的高Q值Y型声表面波(SAW)质量沉积传感器的通带纹波,并分别在振荡和非振荡模式下比较了这些传感器的通带纹波和Q值.分析了获得高Q值的原因.理论和实验结果表明:均匀孔径无反射栅的传感器旁瓣抑制为10dB,振荡模式下其Q值为5 289;通过孔径变迹设计,传感器的旁瓣抑制和Q值分别改善到25dB和8689;而对孔径变迹并加入倾斜反射栅的传感器,这两个参数提高到25dB和12477.非振荡模式下带反射栅的传感器比没有反射栅器件的通带纹波约低2dB.因此,变迹IDT和金属反射栅的应用是SAW质量传感器Q值的改善的两个重要因素.由于Q值改善,质量沉积灵敏度达到5.24 GHz·cm2/g     

微通道导引下数字微流体快速混合

微流体混合是微流控芯片急需完善的重要操作单元,提出了在声表面波驱动下实现微通道内数字微流体快速混合方法.在1280YX-LiNbO3基片上设计相互垂直排列的两叉指换能器和反射栅,并在其声传播路径上制作微通道且进行疏水处理以防止微流体偏离运动方向,待混合的数字微流体移液于微通道中,分别在两叉指换能器上分时加RF电信号激发相互垂直声表面波,以驱动微通道中微流体输运、合并及快速混合.输运实验结果表明微流体在没有微通道时运动发生严重偏离声传播方向;混合实验表明:相比于自由扩散混合,声表面波作用极大地提高微通道中微流体混合速度且混合程度更高.     

Detailed investigation of capacitive micromachined ultrasonic transducer design space

In this study, we present general design guidelines for MEMS ultrasonic transducers, capacitive micromachined ultrasonic transducers (CMUTs), obtained from finite element models with a statistical design of experiment approach. The design space is illustrated using 2-D response surfaces as a function of various geometrical parameters and material selections. Important transducer figure of merits such as operation frequency, fractional bandwidth, collapse voltage and transformer ratio are investigated. Our study illustrates that while keeping geometrical parameters constant, changing the material selection to silicon carbide from silicon dioxide results in a 2.4 times increase in the transformer ratio, and more than 2.5 times increase in the operating frequency while keeping the bandwidth the same. Furthermore, our studies indicate that for a CMUT membrane with an aspect ratio of 4, using a spring constant value obtained analytically results in an error of 160% for the collapse voltage and transformer ratio values.     

Finite element modeling,characterization, and optimization design for the polymer-typed capacitive micro-arrayed ultrasonic transducer

This study constructs a two-dimensional axisymmetric finite element model (FEM) of the polymer-typed capacitive micromachined ultrasonic transducers (P-CMUT). The electromechanical FE model is created using the APDL programming technique. The ANSYS multiphysics solver with sequential approach and the Physics environment files are applied for the solution of the electrostatic-structural coupled-field analysis. Simulations are performed to investigate the operational characteristics, such as collapse voltage and the resonant frequency of the P-CMUT. The numerical results are found to be in good agreement with experimental observation. Having confirmed validity and accuracy of the proposed numerical model, the study of influence of each defined parameter on the collapse voltage and resonant frequency of the P-CMUT are also presented. To solve some conflict problems taken place in diverse physical fields, an integrated multi-objective design method involving electrical and mechanical characterization is developed to optimize the geometric parameters and material properties of the P-CMUT. The optimization search routine conducted using the genetic algorithm (GA) is connected with the commercial FEM software ANSYS to obtain the best design variable using multi-objective functions. The results show that the optimal parameter values satisfy the conflicting objectives of the design procedures, namely to minimize the collapse voltage while simultaneously maintaining a high resonant frequency. Overall, the presented results confirm that the combined FEM/GA optimization approach provides an efficient and versatile means for optimization design of the P-CMUT.     

Controllable fabrication and electromechanical characterization of electrophoresis assembled single-walled carbon nanotube-polymer film transducers

This paper presents a controllable electrophoresis allowing a directed deposition of negatively charged single-walled carbon nanotubes (SWNTs) on an electro-active polymer to fabricate thin-film transducers under an electric field excitation. The assembled high-density SWNT networks are verified with SEM micrograph and Raman spectroscopy, and the electric filed-induced mechanism for electrophoresis of SWNT is investigated using electrochemical analysis technique. The dynamic electromechanical properties are characterized by a combinative approach of piezoelectric excitation and laser vibrometer measurement. A remarkable performance enhancement and tunability for such thin-film transducers in both resonant frequency and quality factor is demonstrated, compared with pure polymer. This observed enhancement can not only be exploited to tailor the thin-film transducers for desired electromechanical properties, but also create versatile pathways for variety of applications including polymeric electronic technologies.     

硅微压电超声换能器的设计与制作

介绍了一种用ZnO薄膜作为压电层的硅微压电式超声换能器(PMUT).该硅微压电换能器的振动基膜采用LPCVD制作的氮化硅薄膜和PECVD制作的二氧化硅形成的复合振动膜结构.文中运用有限元方法对该硅微压电换能器的结构进行了模拟和计算,并进行了预应力对硅微换能器共振频率的影响的分析.实验测得硅微压电式换能器的共振频率为71.36 kHz.本文还使用该硅微超声换能器在油中进行了初步的共振频率点收发信号的实验,接收实验测得信号峰峰值为9 mV左右,发射实验标准水听器接收信号峰峰值为0.8 mV左右.     

An Intelligent,multi-transducer signal conditioning design for manufacturing applications

This paper describes a flexible, intelligent, high bandwidth, signal conditioning reference design and implementation, which is suitable for a wide range of force and displacement transducers in manufacturing applications. The flexibility inherent in the design has allowed more than 10 specialised transducer conditioning boards to be replaced by this single design, in a range of bespoke mechanical test equipment manufactured by the authors. The board is able to automatically reconfigure itself for a wide range of transducers and calibrate and balance the transducer. The range of transducers includes LVDT, AC/DC strain gauge and inductive bridges, and a range of standard industrial voltage current interface transducers. Further, with a minor low-cost addition to the transducer connector, the board is able to recognise the type of transducer, reconfigure itself and store the calibration data within the transducer, thereafter allowing a plug-and-play operation as transducers are changed. The paper provides an example of the operation in typical manufacturing test application and illustrates the stability and noise performance of the design.     

用于压电换能器的频率跟踪驱动电路设计

针对新的压电换能器损耗模型理论,设计并实现了跟踪最佳驱动频率的驱动电路。通过测量验证了最佳频率工作点的存在;利用LC滤波电路克服了电流振荡波形引起的干扰;对换能器进行阻抗匹配设计;通过数字锁相电路,结合FPGA多线程工作模式,实现了最佳频率跟踪。实验结果,在新的频率跟踪系统下,换能器的发热量降低为原来的一半,相较于定频系统运行更加稳定。     

逻辑门混频器的特性分析与选择

在基于频率输出的传感器测量电路设计中,存在如何测量由测量参数引起的小频率增量问题,将被测信号和参考信号进行混频并进行滤波可以解决这个问题.将仅频率变化的两准数字信号施加于逻辑门进行混频,对混频器输出的特性进行了理论分析和实验验证,结果表明:异或门和同或门用作差频测量的混频器时,其输出效果明显好于其他基本逻辑门;当信号为...     

电容层析成像系统传感器参数优化——基于正交试验设计法

介绍了电容层析成像系统的工作原理及数学模型,采用有限元分析对传感器灵敏度分布进行仿真,分析了系统中各个传感器参数对传感器性能的影响,提出传感器性能评价函数,并基于正交试验设计确定了一组优化参数,为电容层析成像系统中传感器的设计提供了参考依据。     

海底管道超声检测数据采集模块的设计

应用超声检测技术于海底管道探伤,具有快速、可靠、经济等优点;由于超声中心频率比较高,探头数目也较多,对超声数据采集系统提出了比较高的要求,正是针对这一问题,提出了一种基于LFECP33 FPGA DSP平台的数据采集方案,其中LFECP33是内含8个sysDSP的高性能FPGA,这套系统不仅具有采样频率高和多个通道实时处理高速大容量数据的能力,同时由于整套器件的功耗比较低,非常适用于管道检测中高压高温的环境特点,对超声技术应用于海底管道检测提供了很好的数据采集方案.