Study of a piezoelectric multimorph based micro-scanner

This paper concerns the modeling of a piezoelectric micro-scanner. The micro-scanner presented in this paper uses multimorph-type bending actuators to tilt a square plate mirror. A complete analytical model of the piezoelectric micro-scanner is presented. Each step of the modeling has been validated by Finite Element Modeling. This theoretical model based on strength of material equations calculates the force generated by the multimorphs on the mirror, the profile of the structure and the angular deflection of the mirror. The proposed model, used to optimize the design of the piezoelectric silicon micro-scanner, is intended for further HDL integration, thereby allowing rapid system level simulation and optimization.     

Quality factor of micro cantilevers transduced by piezoelectric lead zirconate titanate film

The quality factors (Q-factor) of micro cantilevers transduced by piezoelectric lead zirconate titanate (PZT) film under atmospheric pressure conditions were investigated and discussed. It was found that Q-factors increased with thicker PZT film. Due to air damping, shorter cantilevers resulted in preferred larger Q-factors. The Q-factor was found to be as high as 450 for a 150-μm long PZT cantilever when using 1.04-μm thick PZT film as the electromechanical conversion medium. Differences in the measured Q-factors when using integrated PZT film self-excitation and external PZT vibrator actuation indicate that energy dissipation induced by the electromechanical coupling in PZT thin films was noteworthy even under atmospheric pressure conditions. Moreover, the mechanical properties of the PZT film were found contribute significantly to decreases of the Q-factor.     

Study of an innovative one-sided actuating piezoelectric valveless micropump with a secondary chamber

Previous studies have indicated that a one-sided actuating piezoelectric micropump (OAPMP) combined with two valves may enhance the liquid flow rate to 4.1 ml/s and make it possible to reach the maximum pump head of 9807 Pa in a limited space. In this study, an innovative one-sided actuating piezoelectric valveless micropump (OAPMP-valveless) has been developed to actuate fluid at a higher flow rate in one direction by adding a secondary chamber. The secondary chamber plays a key role in the application of the valveless micropump: the flow rate of the pump can reach 0.989 ml/s by adding a secondary chamber. The maximum pump head is 1522.5 Pa when using the 0.3 mm-thick secondary diaphragm and the 0.5 mm-thick primary diaphragm. In addition, if a nozzle/diffuser element is applied to the OAPMP-valveless with a secondary chamber, the flow rate can be further improved to 1.183 ml/s at a frequency of 150 Hz. A three-dimensional numerical model of the valveless micropump has been built to compare the measured results with the simulated results.     

Theoretical analysis and experimental study for nonlinear hybrid piezoelectric and electromagnetic energy harvester

A nonlinear hybrid piezoelectric (PE) and electromagnetic (EM) energy harvester is proposed, and its working model is established. Then the vibration response, output power, voltage and current of nonlinear hybrid energy harvester subjected to harmonic excitation are derived by the method of harmonic balance, and their normalized forms are obtained by the defined dimensionless parameters. Through numerical simulation and experimental test, the effects of nonlinear factor, load resistance, excitation frequency and the excitation acceleration on amplitude and electrical performances of hybrid energy harvester are studied, which shows that the numerical results are in agreement with that of experimental tests. Furthermore, it can be concluded that the bigger nonlinear factor, the lower resonant frequency; moreover, there is an optimal nonlinear factor that make the harvester output the maximum power. In addition, the output power of nonlinear hybrid energy harvester reaches the maximum at the optimal loads of PE and EM elements, which can be altered by the excitation acceleration. Meanwhile, the resonant frequency corresponding to the maximum power rises firstly and then falls with PE load enhancing, while it rises with EM load decreasing; furthermore, the frequency lowers with the acceleration increasing. Besides, the larger acceleration is, the bigger power output and the wider 3 dB bandwidth are. Compared with performances of linear hybrid energy harvester, the designed nonlinear energy harvester not only can reduce the resonant frequency and enlarger the bandwidth but also improve the output power.     

压电传感测试技术的应用研究进展

压电传感器以其独特的性能在减振降噪、健康监测、形状自适应控制、损伤监测等方面发挥着重要作用,综述了压电传感测试技术在航空航天、土木、机械、交通工程、铁路行车安全监测等领域的研究进展,并指出了今后有待进一步研究的问题。     

Modeling analysis of a triaxial microaccelerometer with piezoelectric thin-film sensing using energy method

This study applies energy method to derive the system modeling of a triaxial microaccelerometer that consists of a quadri-beam suspension, a seismic mass, and displacement transducers using piezoelectric thin films. Two suspension beams support both ends of the seismic mass, which is fabricated by anisotropic etching of silicon. An out-of-plane acceleration will result in a symmetric bend, and in-plane accelerations will produce asymmetric bend and torsion of the suspension beams. Two piezoelectric thin-film transducers are arranged at both ends of each suspension beam. Eight transducers in total are interconnected such that triaxial accelerations can be measured selectively. The structure stiffness of the suspension beams considers both the silicon beams and piezoelectric films by the use of the laminated beam theory. Therefore, the analytical model is applicable to the accelerometers with thick piezoelectric films. The model is based on the anisotropic material properties of Silicon and PZT and Euler’s beam equation with the assumptions that smaller strains and stresses are negligible. The analytical results of the resonant frequencies and sensor sensitivities to triaxial accelerations are presented and confirmed by finite element analysis.     

压电传感技术的研究及应用

介绍了压电传感器的分类和测量原理,综述了国内外压电传感技术在航空航天、土木、机械、交通、医学等领域健康监测方面的主要应用实例。介绍了基于压电传感测试技术的桥梁振动监测研究,最后讨论了压电传感器在进一步实用化过程中面临的困难和需要解决的问题,并对其应用前景做了展望。     

Design and optimization of parylene nanomechanical cantilevers with integrated piezoresistors for surface-stress based biochemical sensing

The sensitivity of surface-stress based cantilever sensor can be significantly increased by using polymer as the cantilever material. In our previous research, parylene nanomechanical cantilevers with integrated poly-crystal silicon piezoresistors have already been developed for biochemical applications. However, parylene cantilevers exhibit different behaviors compared with their more rigid counterparts. In this paper, a new analytical model has been developed and verified using finite element simulations. The design optimization has also been discussed based on the new analytical model, resulting in several useful design guidelines that are unique to parylene or more generally to polymer cantilevers with integrated poly-crystal or single-crystal silicon piezoresistors for surface stress sensing.     

Fabrication and characterization of cantilevers with integrated sharp tips and piezoelectric elements for actuation and detection for parallel AFM applications

We have developed a new process to fabricate arrays of cantilevers with integrated tips for atomic force microscope (AFM) imaging and a piezoelectric layer for vertical actuation and detection. A good homogeneity of the tip shape is obtained thanks to a self-sharpening effect. The cantilevers have been characterized mechanically and electrically.     

An experimental analysis of electrostatically vibrated array of polysilicon cantilevers

Micromechanical cantilevers are one of the most fundamental and widely studied structures in micro-electromechanical systems. Dynamic response of such cantilevers has long been an interesting subject to researchers and different analytical and experimental approaches have been reported to determine it. Theoretical estimation of different damping mechanisms have been reported over years which are relevant particularly in studying the dynamics of the micro-mechanical structures. Most properties and functionalities of the MEMS devices are invariably dependant on the dynamic response of the devices, which in turn depends on the quality factor of the devices or in other words the overall damping present in the system. This paper presents a thorough experimental analysis of vibration characteristics of micro-mechanical cantilevers of different dimensions. Arrays of polysilicon micro-cantilevers of different dimensions have been designed and fabricated using surface micromachining process. The beams are resonated by electrostatic actuation and their vibration characteristics have been observed using Laser Doppler Vibrometer. Also a thorough analysis of modal behaviour of the beams is presented using analytical approach and finite element method based simulation. Different damping mechanisms have been critically reviewed and a semi-analytical estimation of the overall damping is presented. The results are compared with experimental values.     

Theoretical performance of a coiled coil piezoelectric bimorph

The electromechanical coupling behaviour of a novel, highly coiled piezoelectric strip structure is developed in full, in order to expound its performance and efficiency. The strip is doubly coiled for compactness and, compared to a standard straight actuator of the same cross-section, it is shown that the actuator here offers better generative forces and energy conversion, and substantial actuated displacements, however, at the expense of a much lower stiffness. The device is therefore proposed for high-displacement, quasi-static applications.     

压电蛋白传感芯片制备技术的研究

在石英晶体微天平上用戊二醛交联法固定HBsAb,构建乙肝表面抗原(HBsAg)压电蛋白传感芯片,运用抽检、测试、数据统计分析、正交试验设计和质量检验等方法对芯片制作中的清洗、固定、封阻、检测等步骤进行质量控制,压电蛋白传感芯片稳定性、合格率均有显著提高。对压电蛋白传感芯片制备工艺进行质量控制,是提高芯片技术性能的关键。     

含金属芯压电纤维传感Lamb波方向性研究

含金属芯压电纤维(MPF)是一种新型压电功能器件.阐述了基于小波变换的Lamb波能量因子计算原理,把MPF作为Lamb波传感器,分别采用幅值和小波变换能量因子的方法对MPF传感Lamb波的方向性进行了研究.研究结果表明:MPF对Lamb波的传感表现出很强的方向性.相比采用幅值表征的结果,采用能量因子进行传感方向性表征更...     

Analytical and numerical modelling of AlGaN/GaN/AlN heterostructure based cantilevers for mechanical sensing in harsh environments

Some industrial areas as oil, automotive and aerospace industries, require electromechanical systems working in harsh environments. An elegant solution is to use III-V materials alloys having semiconductor, piezoelectric and pyroelectric properties. These materials, particularly nitrides such as GaN or AlN, enable design of advanced devices suitable for harsh environment. A cantilever structure based on AlGaN/GaN/AlN heterostructures coupled with a High Electron Mobility Transistor (HEMT) can act as an electromechanical device suited for sensing applications. In this article, we present the mechanical modelling of such a structure. An analytical and a numerical model have been developed to obtain the electrical charge distribution in the structure in response to mechanical stress. A theoretical electromechanical sensitivity of 3.5 μC m⁻² was achieved for the cantilever free end displacement of several hundreds of nanometres. Both models show good agreement, presenting less than 5% deviation in almost the whole structure. The differences between the two models that are pronounced near the clamped area can be explained by particular boundary conditions of the numerical model. The topological characterization and numerical modelling allowed the estimation of the equivalent intrinsic residual stress in the structure and the stress distribution within each layer. Finally, the dynamic mechanical characterization of fabricated cantilevers using laser interferometry is presented and compared to numerical modal analysis with less than 10% deviation between theoretical and experimental resonant frequencies. The obtained results enable the use of the analytical model for further study of the electromechanical coupling with the HEMT structure.     

压电传感技术快速检测牛奶中的金葡球菌

以串联式压电传感器为基础构建了一台自动化微生物检测仪,并开发了一种适合该仪器使用的专用培养基。对加入金黄色葡萄球菌的模拟牛奶样品进行了检测,发现检测时间和样品中细菌浓度呈线性关系,求出其关系式并用于细菌数量的测量。测量范围为10~106cells.m l-1,检测时间为3~15 h。结果表明:该方法准确度与国标的平板计数法相当(r≥0.99),但更为灵敏、快速、简便。     

串联电极阵列压电传感技术自动检测病原体

以串联电极阵列压电石英晶体（SPQC）传感器为基础构建了一台8通道微生物自动检测仪。电极插入培养基检测溶液电导的变化。池常数k=0．05m,使用中性、低电导的氨基酸培养基（AaB）,电导控制灵敏度区间为550-600μs。利用拟合-微分的方法简单准确地得到频率检测时间（FDT）。对普通的金黄色葡萄球菌（S．aureus）和痢疾杆菌（S．dysenteriae）进行自动检测,结果表明：FDT和样品中细菌浓度呈线性关系（R〉0．99）,检测范围为10-10^6CFU·mL^-1。该方法准确度与国标的平板记数法相当（置信区间为95％）,但重现性更好,更稳定,灵敏度更高。     

液体层-压电薄板中兰姆波对液体密度的声传感

叉指换能器在液体层 -压电薄板结构中可激发出兰姆波模式 ,兰姆波的相速度与液体介质的密度密切相关 ,并可反映出液体密度的变化。本文对液体层 -压电薄板结构中兰姆波的液体密度声传感过程进行了理论研究和数值分析 ,所得结果表明 ,用兰姆波对液体密度进行声传感是可行的。     

表面四电极含金属芯压电纤维的冲击振动传感特性研究

模仿昆虫毛发感受器的结构和功能,设计制备了一种能测量外部振动的表面四电极含金属芯压电纤维(FMPF)冲击振动传感器.采用干压成型法制备了含铂金芯的压电陶瓷纤维胚体,经过高温烧结、涂镀表面电极、高温极化后,制成FMPF传感器.基于压电方程和振动理论,建立了悬臂梁结构的FMPF冲击振动传感器的理论模型,分析了传感信号与冲击振动角度和幅值的关系.把FMPF固定在基体上,搭建了实验系统,测试了FMPF对冲击振动的响应,验证了理论模型.结果表明,FMPF的传感信号和冲击振动的幅值成线性关系,和方向成"8"字形关系.得出了FMPF传感器能够测量冲击振动幅值和方向的结论.     

基于ANSYS的声表面波氢气传感器压电分析

设计了声表面波氢气传感器的结构,利用ANSYS软件建立了声表面波传感器的有限元模型,并对SAW氢气传感器进行了仿真,最后用数据处理软件Origin分析了敏感薄膜的材料参数对传感器输出的影响.传感器通人1 000× 10-6的氢气后,钯膜的厚度、密度、弹性模量等发生了相应改变,进而导致输出电压、频率等发生改变.分析表明:...