微悬臂梁的平衡和稳定性研究

对原子力显微镜(AFM)在接触和非接触工作模式下的平衡状态和稳定性进行了研究,分析研究了微悬臂梁的长度以及探针与被测样品表面之间的距离对平衡位置的影响,获得了平衡位置与悬臂梁的长度以及与被测表面之间的规律,该结论为微悬臂的设计和改进提供了理论指导。     

基于AFM的微位移测量新方法研究

提出了一种测量物体微位移的新方法。原子力显微镜作为测量工具,样品和扫描器置于待测物体上,物体每移动一定距离就由AFM扫描获得一幅样品图像,由此获得一系列连续的序列图像。采用模板匹配方法检测相邻序列图像的偏移,从而可计算出物体的微位移。实验结果表明,用该方法还可实现物体二维方向的微位移测量,且精度达到纳米量级。     

基于弯曲法的AFM微悬臂梁弹性常数标定技术

原子力显微镜(atomic force microscopy,AFM)在微纳米尺度力学测量领域有着广泛应用,其微悬臂梁探针的弹性常数是直接影响测量结果准确性的关键因素之一.弯曲法是标定微悬臂梁弹性常数的一类重要方法,基于弯曲标定原理提出了一种新的技术实现方案,并研制了相应的标定系统.借助精密运动定位台使微悬臂梁接触超精密天平并产生弯曲,分别以天平和光杠杆机构同步测得接触力和梁的弯曲量,再根据胡克定律直接算得弹性常数.利用所研制的系统对多种型号的微悬臂梁进行了标定,实验结果表明该系统具有良好的准确性和重复性,测量相对标准差小于5％.     

原子力显微镜微悬臂梁品质因数的数字调控技术的研究

为了提高轻敲模式原子力显微镜的微悬臂梁的低品质因数，在分析品质因数调控技术原理的基础上，设计了基于DSP的品质因数数字调控系统。该系统结构简单，操作方便，智能性和实时性好，能够比较精确地调控微悬臂梁振动的品质因数。通过对比液体中微悬臂梁振动的频谱以及蛋白质分子的成像实验证明，该数字调控电路能够提高微悬臂梁的力灵敏度，非常适合用于对软样品的检测。     

基于AFM的微注射量检测装置设计

介绍了一种基于原子力显微镜(AFM)的微注射量检测的新方法,设计聚酯悬臂感应结构,利用原子力显微镜具有纳米级高度分辨率的特点,对聚酯悬臂在注射微滴重力作用产生的挠度进行检测,达到微滴量检测的目的.通过改进检测装置隔震系统的阻尼器结构,抑制影响微滴检测过程的低频扰动因素.最后对30pl内的微注射量进行检测试验.     

基于AFM的煤体微结构研究

比较了扫描电子显微镜和原子力显微镜的原理及特点。得出了AFM的独特优势。用AFM对煤的表面微形貌进行了三维测量，观测到煤中的颗粒和气孔，气孔形状以圆形为主，其次有椭圆形，且边缘光滑，轮廓清晰，据AFM分析，平均气孔孔径为92.25nm，最小孔径10nm，最大孔径800nm。结论表明。用AFM可以观测到煤真实、精确的表面微形貌，为分析瓦斯分子在煤孔隙中的分布提供了一种研究和测量方法。     

MEMS微平面构件的空气阻尼效应研究

对垂直于衬底表面运动的微平面构件产生的空气挤压阻尼进行研究。从非线性修正雷诺方程出发,计入稀薄气体效应,建立微平面空气挤压理论模型,用有限差分法进行求解。研究揭示了在谐振挤压运动周期内挤压膜的性能变化。研究发现,气体稀薄效应必须在理论分析模型中计入,否则,将高估空气阻尼的影响。微构件平面尺寸增大将增大挤压阻尼力,且阻尼力的增大速度大于微构件面积的增大速度。谐振频率的提高将显著增强空气阻尼效应。     

原子力显微镜微悬臂梁的分叉与混沌

以原子力显微镜单自由度模型为研究对象,在考虑激励和摩擦的情况下,应用相轨迹、Poincare图、分叉图等对Lennard-Jones potential力场模型系统进行分析计算,说明在其他参数不变激励频率为基频率时激励振幅对杆的影响,显示随着激励振幅的增大系统将发生分叉,在经过倍周期分叉后系统产生混沌.     

机械构件的弯曲变形与弯曲刚度

分析了影响构件弯曲变形的主要因素及弯曲刚度与弯曲变形的联系和区别。对其在概念上的不同进行论述,并分析影响机械构件弯曲的主要因素,找出提高构件刚度的有效措施是零件结构设计的主要内容。     

硅基微机械表面粘附及摩擦性能的AFM试验研究

在Si（100）基片上制备了十八烷基三氯硅烷（OTS）分子润滑膜，并用原子力显微镜（AFM）对比研究了施加OTS膜前后的硅表面的粘附、摩擦磨损性能。试验考虑了相对湿度和扫描速度对粘附、摩擦性能的影响。结果表明，相对于硅构件来讲，OTS膜表面粘附力较小，具有较小的摩擦因数，呈现较好的润滑性能；硅构件受湿度变化的影响比OTS膜明显。微构件的摩擦性能由于水合化学作用生成Si（OH）。润滑膜，使得其受相互间运动速度影响很大。OTS膜不仅是一种耐磨性较好的润滑膜，而且有良好的稳定性。     

Characterization of MEMS piezoresistive pressure sensors using AFM

Atomic force microscope (AFM) is adapted to characterize an ultrasensitive piezoresistive pressure sensor based on microelectromechanical system (MEMS) technology. AFM is utilized in contact mode to exert force on several different micromachined diaphragm structures using a modified silicon cantilever with a particle attached to its end. The applied force is adjusted by changing the trigger voltage during each engage step of the probe-tip on the diaphragm surface. The contact force is determined from the force plots obtained for each trigger voltage in advanced force mode. Low force values in the range of 0.3–5 μN have been obtained with this method. This force induces strain on the bridge-arm of the diaphragm where the polysilicon resistor is located. The resultant change in the resistance produced due to varying force/pressure is measured using a delta mode current–voltage (I–V) measurement set-up. The contact mode AFM in conjunction with a nanovoltmeter enables the calibration of very sensitive force sensors down to 0.3 μN.     

基于原子力显微的多模式扫描探针显微镜

扫描探针显微镜是目前世界上分辨率最高的显微镜之一,也是纳米技术研究的主要工具。本文在分析原子力显微镜工作原理的基础上,探讨多模式扫描探针显微镜的相关功能,并对扫描探针显微镜的发展前景进行展望。     

运用碳纳米管原子力显微镜针尖减小长程力作用的研究

减小探针和样品表面之间的长程宏观力是原子力显微镜获得高分辨率成像的关键。首先通过理论分析得出影响长程力的主要因素是探针的几何形状和尺寸。然后分别运用几何形状和尺寸不同的原子力显微镜的传统Si针尖和碳纳米管针尖对样品进行扫描试验研究,结果显示碳纳米管针尖较传统针尖获得了高分辨率的图像。这一结果表明,碳纳米管针尖减小了成像中宏观长程作用力的影响,是理想的原子力显微镜针尖。     

激光照射对H_2O_2处理的红细胞膜结构影响的AFM分析

本文首次利用原子力显微镜(atomic force microscope,AFM)的超高分辨率功能研究H_2O_2处理引起的红细胞膜超微结构的变化,及低强度He-Ne激光照射H_2O_2处理过的红细胞使膜结构恢复的情况。实验结果表明,无论是H_2O_2作用还是激光照射红细胞整体都能维持双凹圆盘状结构;但用AFM得到的超微结构图显示H_2O_2作用的红细胞膜表面高低起伏明显,面上平均粗糙度增加,出现较宽、较深的孔洞。随着激光照射剂量的增加,红细胞膜表面的高低起伏减弱,面上平均粗糙度下降,孔洞变浅、变窄,细胞表面趋于平滑。分析表明,H_2O_2与红细胞内游离铁离子发生类Fenton反应产生的羟自由基(·OH)损伤红细胞膜的结构,细胞的超微结构发生较明显的变化,细胞膜表面的平均粗糙度明显增大,出现较深、较宽的孔洞;激光照射消除部分自由基的作用,较小剂量的激光照射能使损伤部分减弱,膜表面的平均粗糙度降低,孔洞变浅、变窄;较大剂量的激光照射使膜表面平均粗糙度进一步降低,孔洞进一步变浅、变窄,损伤进一步恢复。     

基于AFM的机器人化纳米操作系统综述

对基于扫描隧道显微镜(Scanning tunnel microscope,STM)及原子力显微镜(Atomicforcemicroscope,AFM)的纳米操作技术发展进行阐述,针对其中存在的主要问题,引述出机器人化纳米操作的必要性。接着,对国内外机器人化纳米操作系统的研究进展、现状及存在的主要问题进行详细分析,提出基于AFM的机器人化纳米操作系统的结构原型,并指出实现机器人化纳米操作所需解决的关键技术问题及相应的解决方案之一,为进行深入的机器人化纳米操作研究提供了可以借鉴的研究方向。     

An interferometric platform for studying AFM probe deflection

This paper describes an interferometric platform for measuring the full-field deflection of atomic force microscope (AFM) probes and generic cantilevers during quasi-static loading. The platform consists of a scanning white light interferometer (SWLI), holders for the cantilevers, a translation stage, a rotation (tip-tilt) stage, and an adapter plate to connect these items to the SWLI table. Visualization of cantilever bending behavior is demonstrated for snap-in against a rigid surface, cantilever-on-cantilever tests, and a damaged AFM probe. A new approach to normal force calculation using a polynomial fit to the cantilever deflection profile is also presented and verified experimentally. The method requires only the coefficient for the third order (cubic) term from the fit to the deflection profile, the elastic modulus, and the area moment of inertia for the cantilever under test.     

Micromachined Si cantilever arrays for parallel AFM operation

Silicon cantilever arrays with a very small pitch for parallel AFM operations were studied. We fabricated 1x104 in eight groups and 1x30 Si probe arrays and produced a smaller pitch (15 μm) between probe tips by using Si anisotropic etching with a vertical wall shaped oxide mask. The vertical controls of Si probes were able to operate individually or in a group by integrating electrostatic actuators into the cantilevers of the probes. The fabricated Si cantilever arrays showed reasonable dynamic characteristics for the probe cantilever and reliable parallel operation of AFM.     

Quantitative analysis of the number of antigens immobilized on a glass surface by AFM

To develop force measurements using an atomic force microscope (AFM) in a quantitative manner, it is necessary to estimate the number density of target molecules on a sample surface, and for this, the sensitivity of detection should be known. In this study, the AFM was used as a mechanical detector and an antigen and its antibody were used as a model to evaluate the sensitivity of detection. Antigens were immobilized on a glass surface and number density was estimated by monitoring optical absorbance due to product formation by the reaction of crosslinkers. The concentration of antigen was controlled by mixing control peptides. A microbead was used as a probe and antibodies were immobilized on the bead. AFM force measurements were then made for a range of number densities in the order of 10–10⁶ antigen molecules per square micrometer of surface and were compared to evaluate the sensitivity of detection. Our result establishes the reliability of estimating a number of molecules like receptors on the cell surface, and indicates that the AFM is useful as a mechanical detector with high sensitivity.     

High-speed scanning by dual feedback control in SNOM/AFM

We have developed a high-speed scanning near-field optical microscope (SNOM)/atomic force microscope (AFM) system including dual feedback controllers. The system includes an additional piezoelectric actuator with fast response in the z direction and a correction circuit to eliminate unnecessary components from the feedback signal. From the measurement of a patterned chromium layer of 2 × 2 μm² checks on a quartz glass plate, we confirmed that our system had more effective feedback control and faster scanning than current SNOM/AFM systems that use only a piezo-tube. The scanning speed of the present system was estimated to be about five times faster than that of current SNOM/AFM systems.