改进型微悬臂梁弹性常数标定系统

微悬臂梁作为原子力显微镜中感受微观力的关键元件,其法向和横向弹性常数的可溯源测量是微观力准确定量的前提.受微电子加工工艺的限制,微悬臂梁形状参数与其法向弹性常数无法准确标定,其横向弹性常数更是缺少广泛认可的标定方法.在天平法的基础上对标定系统进行了改进设计,超精密电磁天平与光杠杆结构的结合,能够准确测量微悬臂梁弯曲量及所受作用力,提高了法向弹性常数的准确度.设计了微孔样片和倾斜加载方式,实现了横向弹性常数的间接测量.基于本系统分别对3种商用微悬臂梁的法向或横向弹性常数进行了标定,并采用基于扫描电镜的尺寸参数法比对测量,实验结果重复性好、相对偏差小.研究结果表明该校准系统和方法可作为微悬臂梁弹性常数标定的参考方法.     

基于电磁补偿天平的微纳力值标准装置的性能研究

采用基于电磁补偿原理的精密天平,研制了一种微纳力值标准装置。通过高等级的标准砝码对天平进行校准,实现标准装置力值的SI溯源,在500 nN~500μN范围的力值测量标准不确定度小于0.7%。该装置用于对原子力显微镜（AFM）微悬臂弹性常数和微小力值传感器的力值提供准确的溯源。采用多自由度位置调整系统调整被测微悬臂或传感器的位置及俯仰角度,提高了定位准确度。对几种不同弹性常数的AFM微悬臂进行测量,测量结果的标准偏差小于1.6%,满足高准确度微小力值测量的要求。     

微悬臂梁横向弹性系数标定技术

微悬臂梁是新型力学传感器的关键部件,其性能决定力学测试结果的准确度。为了定量研究微悬臂梁与样品表面间的相互作用力,须对微悬臂梁的力学性能进行表征。提出了一种新的微悬臂梁横向弹性系数标定方案:采用精密天平和光杠杆分别测得微悬臂梁的横向扭转力和扭转量,进而可得到微悬臂梁的横向弹性系数。对3种型号的微悬臂梁进行了横向弹性系数的实际标定,结果表明:均方差均小于5%,重复性良好,且与有限元仿真值一致。     

低刚度高谐振频率的新型微压电悬臂梁探针的结构设计

以超高密度信息存储技术为应用背景,设计了低刚度高谐振频率的新型微压电悬臂梁探针,并安排了探针加工工艺流程.通过建立更接近真实结构的悬臂梁模型,推导出了非矩形不等截面多层材料复合悬臂梁的弹性常数和谐振频率计算公式,并算出设计的悬臂梁探针的弹性常数和谐振频率分别为4 N/m和245 kHz.通过悬臂梁几何参数对力学性能影响的分析,从力学性能的角度对用于超高密度信息存储的悬臂梁探针进行了几何尺寸的优化.     

MEMS执行机构在微小力传感器量值溯源中的应用

对一种基于微电子机械系统（MEMS）执行器结构的非接触式三维微小力装置测量原理、装置结构、标定方法、力学特性及使用方法等进行分析。结果表明：该装置可产生空间任意方向微小力,实现空间非竖直方向微小力传感器量值溯源;利用该装置对微小力传感器进行量值溯源时,能大幅减小极板间距离测量与控制不确定度对输出微小力影响,装置无需配备复杂昂贵的位移控制与测量辅助装置便可达较高精度。对简化微小力传感器量值溯源装置结构具有较大实际意义。     

微力微位移天平测试方法

介绍了一种简单有效的微力、微位移天平测试方法,通过对薄型硅悬臂梁进行力—挠度特性测试进而提取材料杨氏模量的方法是简便、可行的。还介绍了用于测量薄膜应力的悬臂梁挠曲法,对于硅上热生长1.1μm SiO_2的结构,测得SiO_2膜内的压应力为200～230MPa.微力微位移天平测试方法操作方便,仪器成本低,具有较高精度。     

微力微位称天平测试方法

介绍了一种简单有效的微力，微位移天平测试方法，通过对薄型硅悬臂梁进行力一挠度特性测试进而提取材料杨氏模量的方法得简便，可行的，还介绍了用于测量薄膜应力的悬臂梁挠曲法，由于硅上热生长１．１μｍＳｉＯ２的结构，测得ＳｉＯ２膜内的压应力的２００～２３０ＭＰａ，微力微位移天平测试方法操作方便，仪器成本低，具有较高精度。     

适体和蛋白质解离常数检测方法比较分析

对基于石英晶体微天平（QCM）生物传感器的两种检测核酸适体与蛋白质解离常数方法进行了比较,提出来一种更加精确合理的检测流程。以凝血酶和凝血酶适体 TBA15为模型,耗散型石英晶体微天平（QCM-D）为传感器,实时检测末端修饰巯基适体的固定、表面封闭剂对非特异性结合位点封闭以及两种不同的蛋白进样方式引起的频率响应,实验数据拟合得到解离常数。不同蛋白的进样方式得到的解离常数不同,非特异性位点的封闭也同样影响解离常数的检测。从低浓度到高浓度依次通入固定体积蛋白的进样方式,实验重复性高且消耗样品量小于1μg,是较为理想的检测方式。     

仿生湿吸二维微力传感器设计与试验研究

设计了一种L型的二维微力传感器,该二维微力传感器采用悬臂梁式结构。在弹性力学和材料力学基础上,利用Solidworks三维建模软件和ANSYS仿真软件对传感器分别进行模型建立和有限元应变分析。对该二维微力传感器的实体进行标定,得出了力和输出电压之间的关系。然后,在设计与分析二维微力传感器的基础上,研制了二维微力传感器阵列测试系统。最后,在测试系统实施了不同预压力下的湿吸力测试试验,验证了传感器和系统的可靠性。     

开孔变截面微悬臂梁传感器的等效刚度和固有频率

研究新型开孔变截面微悬臂梁传感器的等效法向刚度及其对固有频率的影响.首先,考虑微梁纵截面孔洞结构引起的弯扭耦合效应,利用二次积分法获得在自由端集中载荷作用下悬臂梁的挠度,基于弹性材料的Hooke定律建立了微梁等效法向刚度分析的解析模型.然后,采用Rayleigh法获得了微梁的固有频率.最后,通过比对实验结果和有限元结果对解析模型进行了验证.研究表明:解析模型对于开孔变截面微梁刚度和频率的预测和标定具有较好的精度;微梁的等效刚度和固有频率与跨宽比负相关,却与内外宽度比正相关.有关结论可为新型变截面微纳机械传感器的设计提供理论依据和参考.     

航空发动机矢量推力测量系统的静态校准及不确定度评定方法研究

介绍了航空发动机矢量推力测量系统的静态校准原理,建立了静态校准的数学模型,并通过多元回归分析方法得到了各阶模型的校准系数.在此基础上,针对目前矢量推力测量系统缺少精度评定规范的问题,提出了一种基于校准系数误差传递的不确定度评定方法,并与传统的校准残余误差方法和验证残余误差方法进行了比较.校准实验结果表明,由于加载条件不...     

飞行试验脚蹬力测试系统在线校准技术研究

飞行试验中脚蹬力测试系统的校准,常规采用将测试系统拆卸后进行校准的方式,易造成传感器损坏,且所经环节多工作效率低。本文对脚蹬力传感器测力原理及供电电压对传感器输出的影响进行研究,提出一种新的脚蹬力测试系统在线校准方法以解决上述问题。并对该方法进行验证,对多架试验机共6组脚蹬力测试系统分别采用传统方法及新方法进行校准,结果表明两种校准方法下的校准曲线基本一致,最大偏差不超过总测量范围的0.15%,满足飞行试验机载测试精度的需求。最终表明该校准方法准确可靠,可应用于机载脚蹬力测试系统校准。     

力传感器在发动机推力试验工况下的技术特性分析

力传感器是工业测控领域的常见测量仪器,其数据准确程度是应用效果的重要保证.力传感器在航空发动机试车台等推力测量场合的受力工况比较复杂,与实验室校准时的工作状态存在明显差异,由此引入的数据偏差需要进行分析和校准.通过对发动机推力试验中常用的应变式力传感器的使用工况进行分析,并与实验室校准条件进行比较,对力传感器在不同的环...     

Analysis of Tsai calibration method using two- and three-dimensional calibration objects

Camera calibration is a fundamental process for both photogrammetric and computer vision. Since the arrival of the direct linear transformation method and its later revisions, new methods have been developed by several authors, such as: Tsai, Heikkilä and Zhang. Most of these have been based on the pinhole model, including distortion correction. Some of these methods, such as Tsai method, allow the use of two different techniques for determining calibration parameters: a non-coplanar calibration technique using three-dimensional (3D) calibration objects, and a coplanar technique that uses two-dimensional (2D) calibration objects. The calibration performed by observing a 3D calibration object has good accuracy, and produces very efficient results; however, the calibration object must be accurate enough and requires an elaborate configuration. In contrast, the use of 2D calibration objects yields less accurate results, is much more flexible, and does not require complex calibration objects that are costly to produce. This article compares these two different calibration procedures from the perspective of stereo measurement. Particular attention was focused on the accuracy of the calculated camera parameters, the reconstruction error in the computer image coordinates and in the world coordinate system and advanced image-processing techniques for subpixel detection during the comparison. The purpose of this work is to establish a basis and selection criteria for choosing one of these techniques for camera calibration, according to the accuracy required in each of the many applications using photogrammetric vision: robot calibration methods, trajectory generation algorithms, articulated measuring arm calibration, and photogrammetric systems.     

材料试验机同轴度检测方法及影响因素分析

材料试验机同轴度是影响其试验力传递效率的重要指标。各级计量部门按照检定规程规定的方法开展对试验机同轴度指标的周期性检测工作，而检测过程中存在多方面因素会影响结果的准确性从而影响其合格性判定结果。当前试验机同轴度检测所依据的检定规程中给出了多种检测方法，多种方法的差异性、适用性和可比性也往往会引起疑惑。通过比较分析，对几个相关标准文件规定的几种同轴度检测方法进行了适用性阐述，通过算法对比和仿真分析得出引伸计式同轴度测量方法和应变计式同轴度测量方法的差异，并从安装定位、初始拉力、夹持长度等方面，对影响检测结果的几个因素进行分析探讨，为完善同轴度检测操作方法，提升数据的准确性和可比性提供参考依据。     

Silicon nitride cantilevers with oxidation-sharpened silicon tips for atomic force microscopy

High-resolution atomic force microscopy (AFM) of soft or fragile samples requires a cantilever with a low spring constant and a sharp tip. We have developed a novel process for making such cantilevers from silicon nitride with oxidation-sharpened silicon tips. First, we made and sharpened silicon tips on a silicon wafer. Next, we deposited a thin film of silicon nitride over the tips and etched it to define nitride cantilevers and to remove it from the tips so that they protruded through the cantilevers. Finally, we etched from the back side to release the cantilevers by removing the silicon substrate. We characterized the resulting cantilevers by imaging them with a scanning electron microscope, by measuring their thermal noise spectra, and by using them to image a test sample in contact mode. A representative cantilever had a spring constant of /spl sim/0.06 N/m, and the tip had a radius of 9.2 nm and a cone angle of 36/spl deg/ over 3 /spl mu/m of tip length. These cantilevers are capable of higher resolution imaging than commercially available nitride cantilevers with oxidation-sharpened nitride tips, and they are especially useful for imaging large vertical features.     

1/f noise considerations for the design and process optimization ofpiezoresistive cantilevers

Piezoresistive cantilevers are limited by two major noise sources: Johnson noise, which is independent of frequency, and conductance fluctuation noise, which has a 1/f spectrum. The 1/f fluctuations of piezoresistive cantilevers are shown to vary inversely with the total number of carriers in the piezoresistor, as formulated by Hooge in 1969. Therefore, while 1/f noise is reduced for large heavily doped cantilevers, sensitivity considerations favor thin lightly doped cantilevers. Balancing these conflicting constraints produces optima for many design and processing parameters. For a cantilever with specified spring constant and bandwidth requirements, optima are identified for the beam thickness and length, and it is shown that the legs should be between 1/3 and 2/3 of the total length with a doping depth that is 1/3 of the beam thickness. Additionally, an optimal doping concentration is identified as a function of the cantilever volume and the measurement bandwidth. Annealing reduces 1/f noise, but causes a loss in sensitivity due to dopant diffusion, and an optimal anneal is computed with a typical diffusion length 10^-8 cm. The analysis, methods, and some of the conclusions of this paper are also applicable to other types of piezoresistive sensors