复合L形宽频压电悬臂梁的建模与仿真

为提高单频压电悬臂梁的振动能量采集转换效率,提出一种复合L形压电悬臂梁的宽频拓展技术,通过在单频压电悬臂梁水平结构中增加一个辅助垂直悬臂梁,组成L形压电悬臂梁,通过控制L形压电悬臂梁的结构和材料参数使悬臂梁的2阶模态频率为1阶模态频率的2倍,将1阶、2阶模态频率串联起来形成一个宽频的谐振带。利用拉格朗日方程和模态假设法建立了L形压电悬臂梁的频率方程和振动方程,通过数值仿真分析了L形压电悬臂梁结构和材料参数对其频率特性和振动特性的影响,并确定了系统的最佳结构和材料参数,实例验证了悬臂梁宽频拓展方法的正确性。     

基于微纳光纤谐振环的温度传感器研究

该项工作制作并验证了基于微纳光纤结型谐振环的高灵敏度且扩大测量范围的温度传感器。 在微纳光纤谐振环中产 生多个模式并参与谐振,多个模式谐振的光谱相互叠加,形成带包络的游标光谱。 通过提取游标光谱的包络线,实现高灵敏度 的温度测量,灵敏度高达-10 nm/ ℃ 。 但计算得到利用游标光谱时的温度测量范围仅约为 4℃ 。 为解决测量范围过小的问题, 将包络光谱与单一频率组分对应的谐振光谱相结合,使测量范围扩大至约 20℃ 。 相比于单一频率组分对应的谐振光谱,利用 游标包络光谱实现了灵敏度约 1 600 倍的放大。 该方案利用游标效应提高温度测量灵敏度的同时,利用单一频率组分对应的 谐振光谱扩大了游标光谱的温度测量范围,提高了传感器的性能和实用性。     

基于SH-SAW谐振器的无线温度传感器研究北大核心CSCD

基于128°YX铌酸锂压电衬底设计制作了窄带、高Q值的水平剪切声表面波(SH-SAW)谐振器,研究了其温度特性,并基于该谐振器制作了无线温度传感器。研究结果表明,该SH-SAW谐振器在常温至250℃内保持良好的谐振性能,频率温度系数为-24.33 kHz/℃。基于该SH-SAW的无线温度传感器在常温至250℃温度范围内实现了温度的准确无线测试,测温误差为0.93%,且具有良好的重复性。     

基于SH-SAW谐振器的无线温度传感器研究

基于128°YX铌酸锂压电衬底设计制作了窄带、高Q值的水平剪切声表面波(SH-SAW)谐振器,研究了其温度特性,并基于该谐振器制作了无线温度传感器。研究结果表明,该SH-SAW谐振器在常温至250℃内保持良好的谐振性能,频率温度系数为-24.33 kHz/℃。基于该SH-SAW的无线温度传感器在常温至250℃温度范围内实现了温度的准确无线测试,测温误差为0.93%,且具有良好的重复性。     

基于声表面波的电站锅炉受热面温度监测传感器研究

为了直接测量电站锅炉高温受热面的温度,对声表面波温度传感器进行有限元模拟及制备,并进行高温实验研究.选择硅酸镓镧(LGS)作为高温压电基底材料,对Au、Pt、Cu三种电极及不同厚度进行模拟分析,最终选择100 nm厚的Au电极.实验结果表明该传感器谐振频率随温度呈下降趋势,温度灵敏度较好为5.89 kHz/℃,且高温时...     

低温环境下MEMS微构件的动态特性及测试系统

研究了微机电系统(MEMS)微构件的谐振频率等动态特性在低温环境下的变化规律,从理论上分析了改变环境温度对微悬臂梁谐振频率的影响,并对低温环境下微构件的动态特性测试技术进行了研究。研制了低温环境下MEMS动态特性测试系统,采用半导体冷阱实现低温环境,利用压电陶瓷作为底座激励装置的驱动源,通过底座的冲击激励,使微悬臂梁处于自由衰减振动状态,使用激光多普勒测振仪对微悬臂梁的振动响应进行检测,从而获得微悬臂梁的谐振频率。利用研制的测试系统,在-50℃～室温的环境下对单晶硅微悬臂的谐振频率进行了测试,结果表明,随着温度的降低,微悬臂梁的谐振频率略有增大,其谐振频率的温度变化率约为-0.263 Hz/K,与理论分析的结果基本一致。该测试装置能够有效地完成在-50℃～室温环境下微构件的动态特性测试。     

基于 CBAM-CNN 和压电悬臂梁的温度解耦质量感知方法

悬臂梁结构广泛用于微小质量测量,而温度变化会引起测量结果漂移。 传统测量方法需要在温度稳定的环境中进 行,但实际应用中通常难以满足此要求,且温度漂移对测量的影响难以直接解耦。 本文提出了一种基于数据驱动,CBAM-CNN 和压电悬臂梁的自适应温度解耦质量感知方法。 首先,搭建谐振式压电悬臂梁温控测量平台采集不同质量负载下的阻 抗响应信号,设计自适应加权预处理方法以增强结构特征并突出有限样本中的关键信息;其次,设计基于混合领域注意力机 制的 CBAM-CNN 网络来评估信号中多个谐振峰的相对关系,实现温度解耦和质量感知。 实验结果表明,该方法在 25℃ 至 55℃ 的温度范围内的对 0. 1 ~ 1 g 的质量感知准确率高达 99. 70% ,无需进行温度补偿即可实现大跨度温度下的精确质量 感知。     

一种仿生型无阀压电泵

针对传统的容积型流阻差式无阀压电泵具有吸入周期和排出周期,存在着流动脉动大、流量小的问题,提出一种新型的鱼鳍摆动式无阀压电泵。模仿在鱼类中巡游速度最快的金枪鱼的鱼体结构,设计了压电双晶片结构的压电振子,并将其尾鳍设计成柔性叶片状。分析了压电双晶片结构悬臂梁的受力变形、模态振型在机电转换效率方面的关系。研制了泵的样机并测量了激励电压在100 V时泵的流量。实验结果表明:振子工作在1阶振型时,泵水效应不明显;振子工作在2阶振型时,谐振频率为740 Hz,泵的流量为266 mL/min;振子工作在3阶振型时,谐振频率为1 280 Hz,泵的流量为105 mL/min。     

高温环境下微悬臂梁谐振频率温度特性及测试技术研究

对单晶硅微悬臂梁在高温环境下的动态特性进行了理论分析,研制了高温环境下的MEMS动态特性测试系统,采用压电陶瓷作为底座激励装置的驱动源,设计了一个可动的机构,解决了压电陶瓷在高温环境下使用的难题;通过激励装置进行冲击激励,使用激光多普勒测振仪对微悬臂梁的振动响应进行检测,对微悬臂梁受冲击后的时域信号进行分析,获得微悬臂梁的谐振频率。利用研制的高温环境下MEMS动态特性测试系统,在室温至300℃的温度环境下对单晶硅微悬臂梁的动态特性进行了测试,结果表明随着温度的升高其谐振频率会有轻微的减小,验证了理论分析的结果。     

应用石英音叉谐振器的智能温度传感器

为了实现高精密温度测量,设计了高性能数字温度传感器,该传感器由石英音叉谐振器,数字接口电路和基于现场可编程门阵列的传感器重置控制算法构成。依据石英晶体压电效应原理,对石英音叉谐振器的热敏切型和电极设置进行了研究;基于力学振动原理,导出石英音叉谐振器弯曲振动模式的微分方程;讨论了谐振式温度传感器的工作原理,提取出石英音叉温度传感器的特征参数并进行了非线性误差分析;采用光刻和侵蚀技术加工制作了石英音叉谐振器。该传感器的频率输出信号通过数字接口进入现场可编程门阵列,通过重置控制算法实现传感器的重置和现场自动校验。实验结果表明,在-20 ~140 ℃,该传感器的灵敏度可达65×10^-6/℃,测温分辨率为0.001 ℃,响应时间为1 s,测温精度为0.01 ℃。     

Piezoelectric based resonant mass sensor using phase measurement

The paper presents design, development and testing of a resonant sensor to measure mass in the range of 0-12 g. The sensor is built using cantilever structure with piezoelectric excitation, sensing and microcontroller based closed loop electronics. The sensor measures the unknown mass by measuring the shift in resonance frequency of the cantilever beam. The shift in resonance frequency for a change in mass is detected by measuring the phase difference between the piezoelectric sensor output and actuator input using microcontroller. The proposed measurement system is simple and accuracy is found to be ±1.2% of full scale deflection.     

Resonance based DC current sensor

The paper presents design, development and testing of a resonant proximity DC current sensor to measure current in the range of 0-20 mA. The sensor is built using cantilever structure with piezoelectric excitation, sensing and closed loop electronics. The sensor measures the DC current by measuring the shift in resonance frequency of the cantilever beam. The proposed measurement system is novel, simple and accuracy is found to be 1.1% of full scale deflection.     

基于槽式悬臂梁结构的微质量传感器设计

压电式微质量传感器的测试精度直接依赖于结构频率对质量变化的灵敏程度。本文利用对称槽型梁和压电薄膜组成的对称敏感结构,提出了一种提高传感器灵敏度的结构设计方法,并设计了一种高精度谐振式微质量传感器。建立了结构频率变化对吸附质量敏感性的分析模型,并研究了槽型截面参数、自振频率及振动模态对灵敏度的影响。与矩形截面结构进行了仿真与实验对比,结果表明,相同几何尺寸参数下,槽型截面悬臂梁的一阶自振频率为1 851 Hz,矩形截面悬臂梁的一阶自振频率为1 610 Hz,相应的传感器灵敏度则分别为3.12×10⁴ Hz/g和1.5×10⁴ Hz/g,前者是后者的2倍。该项设计为提高微质量传感器灵敏度提供了一种新思路。     

常温下硅微谐振加速度计零偏稳定性的提高

考虑环境温度会影响硅微谐振加速度计(MSRA)的测量精度,本文研究了谐振梁的频率漂移及抑制方法以便提高其在常温下的零偏稳定性。针对结构热膨胀导致的应力进行了建模仿真,并根据仿真结果优化设计了一种低热应力的双端固支梁的结构来降低热膨胀系数不匹配带来的频率漂移。实验测得新结构的单梁谐振频率的温度系数从典型结构的约30Hz/℃降为-1.5Hz/℃,与仿真结果-1.14Hz/℃基本一致。为了进一步提高该加速度计的零偏稳定性,设计了一种高精度测温电路用来补偿温漂,该电路测温灵敏度为96.25mV/℃,测量噪声约为0.000 2℃。实验结果表明,采用优化后的结构结合线性温度补偿的方法,可使该硅微谐振加速度计的1h零偏稳定性在常温下达到10μg以下,比改进前实验室获得的52μg水平提升了80%,满足了高精度加速度测量的要求。     

基于啁啾光纤光栅的电压传感性能研究

电压的实时测量是电力系统稳定、安全的关键。提出了一种基于啁啾光纤光栅的电压传感器,利用压电陶瓷的逆压电效应带动黏贴在其上面的传感啁啾光栅发生形变,使传感啁啾光栅的波长发生漂移,通过检测传感啁啾光栅和参考啁啾光栅反射光包络的强度变化,获取被测电压的幅值和频率信息。理论分析了电压与光功率变化的关系,搭建了带温度补偿的双啁啾光栅传感系统,实验研究了传感器的静态和实时动态特性。实验结果表明,该传感器的相关系数R2为0.999 8,电压灵敏度达到0.048mW/V,既能直接检测直流电压,也能较好地检测交流电压及其频谱信息,为在复杂环境评估电能质量提供了参考。     

Parylene增强型声表面波传感器及其温度响应

针对声表面波(SAW)传感器对品质因数、寿命和成本的要求,研制了Parylene增强型SAW传感器。根据金属剥离工艺要求,利用LOR剥离胶和AZ5214光刻胶双层胶旋涂工艺制作了梯形结构;在传统光学光刻条件下制作了2μm的超细叉指电极。传感器制作过程利用了MEMS工艺,不仅实现了传感器的微型化,还可以批量化生产,得到的以石英为基底的传感器谐振频率达到249.077 953 MHz。最后在传感器的表面镀制Parylene聚合物薄膜以提高基底温度灵敏度。实验对比了未增强型(未镀Parylene)和增强型SAW传感器(镀Parylene)的温度灵敏度。结果显示:未增强型SAW传感器温度灵敏度为2.048kHz/℃,Parylene增强型SAW传感器温度灵敏度为2.855kHz/℃,比前者提高了0.807kHz/℃,且镀Parylene之后谐振频率变化量与温度具有较好的线性度,线性相关系数达到0.996 15。实验证明,Parlene增强型SAW传感器的性能优于未增强的SAW传感器。     

Modeling and characterization of piezoelectric cantilever in fluids at different temperatures

This paper introduces measurement and modeling of a piezoelectric beam used as a sensor in different types of liquids. It is immersed in different fluids at temperatures increasing from 20 °C to 50 °C. The working principle is based on detecting different resonance frequencies of the cantilever in different solutions. The oscillation of piezoelectric beam is measured using a vector network analyzer. An electrical equivalent circuit derived from a resonator model is used to simulate the experimental data. These calculated circuit constants have been related to physical properties of liquids under test. The combination of these liquids which includes non-conducting and conducting solutions, exhibiting low and high viscosity covers a good range of common physical properties of fluids. Main focus of this research is to explore the capability of piezoelectric cantilever as a liquid sensor with the influence of temperature. The equivalent circuit model has been proved to be viable to fit experimental data in non-conducting solution but less effective in conducting solution.     

Fabrication and characterization of PMN-PT single crystal cantilever array for cochlear-like acoustic sensor

We have successfully fabricated piezoelectric PMN-PT single crystal cantilever array. Each PMN-PT cantilever has a different length to achieve different resonance frequencies. The width and thickness of PMN-PT cantilever array are 200 μm and 10 μm, respectively. Resonance frequencies of PMN-PT cantilevers were measured with laser interferometer, and charge sensitivity was measured with charge-measuring device. PMN-PT cantilever array was installed in a noise-shield case. The array was then exposed to sound pressure frequency corresponding to resonance frequency to measure its sensitivity. The experimental results show that the PMN-PT cantilever array has high sensitivity to the sound pressure. This implies that the single crystal PMN-PT cantilever array is a potential candidate for a cochlear-like acoustic sensor.     

Design and application of fiber Bragg grating (FBG) geophone for higher sensitivity and wider frequency range

The fiber Bragg grating geophone sensor with higher sensitivity and wider frequency range was reported. The methods to increase the sensitivity of the FBG cantilever sensor were presented. The acceleration sensitivity of the optimized FBG geophone is 220 pm/g, and the resonant frequency can reach to 295 Hz. The experiments show that the FBG geophone system has the minimum detectable acceleration of 1 mm/s². Some factual application examples of using this fiber Bragg grating geophone monitoring system for micro seismic monitoring in coal mine were presented.     

Expression of picogram sensitive bending modes in piezoelectric cantilever sensors with nonuniform electric fields generated by asymmetric electrodes

Single-layer uniform cross-sectioned piezoelectric macro-cantilevers fabricated with an asymmetric electrode configuration enabled electrical measurement of picogram-sensitive resonant bending modes in liquids. Bending modes were otherwise not electrically measurable without excitation by a nonuniform electric field created by the geometric asymmetry in electrode design used. Electrode modification was confirmed by energy-dispersive X-ray spectroscopy (EDS). Mass-change sensitivity was tested using both bulk density changes and surface chemisorption experiments in a continuous flow apparatus. Significant response to density changes as small as 0.004 g/mL was measured. A sensitivity limit of ～1 picogram in liquid was determined from 1-dodecanethiol chemisorption experiments. The sensitivity decreased with chemisorbed mass and was log-linear over five orders of magnitude. The observed resonance responses were in agreement with previously reported models of resonating cantilever sensors. This work demonstrates experimentally for the first time that introducing electrode asymmetry enables measurement of bending modes in cantilevers containing only a single piezoelectric layer.