Effects of scratching directions on AFM-based abrasive abrasion process

AFM-based single abrasive abrasion process is widely employed in the surface micro/nanomachining for fabrication of structures at the nanometer scale. The wear depth and roughness are significantly important in the application of these structures. To study effects of scratching directions on the wear depth and roughness within the wear mark, single groove scratching test and wear test on the surface of polished single crystal silicon were carried out using AFM with a pyramidal diamond tip. Single groove scratching tests indicated that tip geometry leads to different removal states such as cutting and plowing. At the same load, deeper wear depth and rougher surface were produced by using the scratching direction perpendicular to the long axis of the cantilever rather than parallel to the long axis of the cantilever. Surface roughness decreases with respect to the feed scratching perpendicular to the long axis of the cantilever, whereas while scratching along the long axis of the cantilever, the surface roughness is rougher at the small feed. This is attributed to the different stiffness of the cantilever along different scratching directions and different removal states between the tip and sample.     

基于原子力显微镜扫描的金刚石刀具纳米刃口轮廓测量方法研究

基于扫描探针理论,本文介绍了一种超精神加工金刚石刀具刃口锋锐轮廓的测量方法,给出了测量图象并分析了测量结果,首次对金刚石刀具刃口轮廓参数进行了ＡＦＭ扫描原理下的初步评定。这一方法可提高金刚石刀具刃口锋锐度的测量准确度,对进一步分析刃口参数如何影响超精密加工表面质量具有指导意义。     

基于原子力显微镜的线宽粗糙度测量

给出采用原子力显微镜(Atomic force microscope,AFM)测量线宽粗糙度(Line width roughness,LWR)的分析步骤。分析线宽和LWR及其偏差随刻线横截面位置的高度变化的关系,线宽及其偏差和LWR及其偏差随刻线横截面位置的高度值增加而减小。分别采用四种边缘提取算子提取了碳纳米管针尖AFM测量的刻线顶部线宽边缘,计算了刻线顶部线宽和LWR,顶部线宽和LWR测量结果对边缘提取算子不敏感。结合被测单晶硅台阶的顶表面和底表面加工方法,提出采用各扫描线轮廓高度相等的方法校正AFM压电驱动器的z向非线性。比较了采用普通氮化硅探针针尖、超尖针尖以及碳纳米管针尖AFM测量名义线宽为1 000 nm刻线LWR的结果,显示采用三种针尖的LWR测量结果存在差异,但考虑到AFM分辨率,可认为测量结果基本相同。因此,为更精确描述刻线边缘,必须提高AFM分辨率。     

On the Abrasion of Ultrafine WC–Co Hardmetals by Small SiC Abrasive

Abrasive wear of a series of WC-(5–14 wt.%)Co hardmetals was investigated employing P800 and P120 SiC abrasive papers. It was found that if fine abradant was utilized, submicron grades demonstrated substantially higher wear rates than the coarse grades. Such a behaviour was associated to different wear mechanisms operating for fine and coarse grades and correlated to the ratio of the abrasive size to size of the hard WC phase.     

The immobilization of animal cells using the cysteine-modified RGD oligopeptide

RGD peptide sequence is an effective cell recognition motif and used to enhance the cell adhesion on desired solid material for cell immobilization. We have synthesized CRGD, CRGD-multiple-armed peptide (MAP), RGD-MAP-C and evaluated their comparative efficacy for cell immobilization. Each peptide was assembled on gold surface and investigated by the atomic force microscopy (AFM) technique in the contact mode. The viability of immobilized animal cells was examined by an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Our results showed that RGD-MAP-C in comparison to others was the most effective proliferation of cells on the gold surface. The goal of this present work is integration to the nano-pattern cell chip bioplatform for biomedical assays or provide valuable insights into cell biology and design of biomaterials. This RGD-MAP-C can be applicable to the nano-pattern cell chip platform.     

IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY（AFM）

An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy (AFM) here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function. Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication's difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe.     

AFM针尖对胶原样品表面一种损伤现象的研究

用AFM对吸附于云母表面的胶原蛋白的研究过程中，观察到一种AFM针尖对样品损伤现象。在小范围的扫描过程中．胶原蛋白在AFM针尖的作用下。产生了明显的移动。改变了其原来平整、均匀分布的表面特征。此现象文献中也曾有报道，在本实验中能重复出现。本文进一步分析讨论这种现象产生的原因，对比了不同成像模式下AFM针尖对样品表面的影响。结果表明，用Tapping Mode(TM)，扫描过程对样品表面几乎不产生影响，但是Non Contact Mode(NCM)在扫描过程中对样品表面产生了损伤作用。证明了TM模式更适合于对生物样品的研究。实验还发现这种损伤的程度和扫描范围的大小、针尖扫描的方向有着很大关系。     

表面活性剂及复配在云母片上吸附的AFM研究

借助原子力显微镜对十二烷基硫酸钠(SDS)/十六烷基三甲基溴化铵(CTAB)及其复配溶液在云母表面的吸附以及吸附后不同的表面形貌和微摩擦特性进行了研究,探讨了摩擦力与表面形貌的关系。结果表明,SDS与CTAB表面活性剂分子都以纳米级颗粒吸附于云母表面;摩擦力受表面形貌的影响,但不成一一对应关系;在0.8和2倍临界胶束浓度(CMC)下,SDS/CTAB=1∶1复配溶液在云母表面吸附后的润滑效应较其它配比好。     

TMX2000型原子力显微镜(AFM)力的标定

根据针尖的形状和各项参数进行了TMX2000型原子力显微镜载荷、粘附力、法向力、横向力及其摩擦力的标定。其标定结果为载荷Fl=0.073×(Ilm-Il0)/Sn×N·m-1,横向力Ft=0.156×It/Sn×N·m-1,摩擦力Ff=0.078×(It -It-)/Sn×N·m-1     

自由磨粒复杂曲面磁力研磨光整加工试验研究

为了实现复杂曲面模具表面高质量高效率磁力研磨光整加工,在3-TPT五自由度并联机床上进行磁力研磨光整加工的试验研究,对复杂曲面模具自动化研磨光整加工进行了初步探索.从理论上研究了自由磨粒磁力研磨光整加工机理,并针对不同形状的加工对象,实验研究了磁感应强度、研磨间隙、磨粒粒度以及研具表面形状对磁力研磨光整加工的影响及其变化规律.     

Effect of the molecular weight on deformation states of the polystyrene film by AFM single scanning

Nanobundles patterns can be formed on the surface of most thermoplastic polymers when the atomic force microscope (AFM)‐based nanomechanical machining method is employed to scratch their surfaces. Such patterns are reviewed as three‐dimensional sine‐wave structures. In the present study, the single‐line scratch test is used firstly to study different removal states of the polystyrene (PS) polymer with different molecular weights (MWs). Effects of the scratching direction and the scratching velocity on deformation of the PS film and the state of the removed materials are also investigated. Single‐wear box test is then employed to study the possibility of forming bundle structures on PS films with different MWs. The experimental results show that the state between the tip and the sample plays a key role in the nano machining process. If the contact radius between the AFM tip and the polymer surface is larger than the chain end‐to‐end distance, it is designated as the “cutting” state that means the area of both side ridges is less than the area of the groove and materials are removed. If the contact radius is less than the chain end‐to‐end distance, it is designated as the “plowing” state that means the area of both side ridges is larger than the area of the groove and no materials are removed at all. For the perfect bundles formation on the PS film, the plowing state is ideal condition for the larger MW polymers because of the chains’ entanglement. SCANNING 35:308‐315, 2013. © 2012 Wiley Periodicals, Inc.     

用原子力显微镜研究阿莫西林对沙门氏菌和单核增生性李斯特菌的抗菌活性

目的:探测阿莫西林作用于沙门氏菌(G)和单核增生性李斯特菌(G~+)后2种菌体的形貌和生物力学特性的变化,探讨阿莫西林的抗菌活性和抗菌机理。方法:通过平板菌落计数法测细菌的失活率,利用原子力显微镜(AFM)对药物作用后细菌的表面形貌及细胞的硬度、粘附力做定性和定量分析。结果:平板菌落计数得,25μg/mL的阿莫西林作用1h后,沙门氏菌的失活率较李斯特菌的失活率大。AFM测量显示,与低浓度阿莫西林作用后,沙门细菌表面出现孔洞,而李斯特菌表面出现裂缝,力曲线测量显示,药物作用后针尖和细胞壁之间的粘附力明显增加,而杨氏模量(E)显著降低。结论:结合AFM图像可知形貌与生物力学特性的变化反映细胞壁的变化,细胞壁的成分由均一性变为异质性从而导致细菌的粘附力增加即F_(native)E_(amoxicillin)通过以上分析进一步探讨阿莫西林的杀菌机理和不同的细菌对阿莫西林的敏感程度。这些AFM数据为阿莫西林的临床应用提供可视化的数据支持。     

T细胞与K562细胞共培养的AFM观察

人类机体的免疫系统很难彻底清除肿瘤细胞,了解T淋巴细胞杀伤肿瘤细胞的整个过程的机理,将为提高免疫系统杀灭肿瘤的效率提供知识基础。本文采用原子力显微镜与倒置显微镜在细胞层面上观察T淋巴细胞进攻杀伤人慢性粒细胞性白血病细胞株——K562细胞的过程,并对T细胞与K562细胞共培养前后的表面形貌和生物机械性质进行表征。结果显示,与培养前相比,共培养后2种细胞数目之和减少,2种细胞的表面形貌和机械力学性质均出现很大差异,表现为:K562细胞,平均粗糙度(Ra)降低,细胞平均高度(Mh)降低,细胞表面出现5～8 cm的孔洞,有的细胞甚至完全破裂溶解。多个T细胞的统计分析结果显示,共培养前,T细胞为静息状态,而共培养后Ra和Mh都显著增加。该方法为研究免疫系统与肿瘤相互作用的机制提供重要的切入点。     

Controlled growth and formation of SAMs investigated by atomic force microscopy

Recently we reported a simple method for obtaining both monolayer thickness and surface patterning using self-assembled monolayers (SAMs). Here we presented a straightforward method for controlling the formation of SAMs over surfaces useful for both chemical and biological applications. Atomic force microscopy (AFM) has been used to investigate the growth mechanism and formation of octadecylsiloxane (ODS) films obtained using a less-reactive silane; octadecyltrimethoxysilane (OTMS). SAMs formation from both OTMS and octadecyltrichlorosilane (ODTS) differ in the hydrolysis step where ODTS results in hydrochloric acid formation, which may affect the delicate features on surfaces. On the other hand, OTMS does not show this behavior. In contrast to monolayer formation from chlorosilane precursors, methoxysilane SAMs have been studied less extensively. Our observations highlight the importance of controlling water content during the formation of ODS monolayers in order to get well-ordered SAMs. We have also seen that, like ODTS, OTMS exhibits monolayer growth through an island expansion process but with a comparatively slow growth rate and different island morphology. The average height of islands, surface coverage, contact angle and root-mean-square (RMS) roughness increase with OTMS adsorption time in a consecutive manner.     

Atomic force microscopy of histological sections using a new electron beam etching method

In order to examine histological sections of the rat vomeronasal epithelium with the atomic force microscope (AFM), we developed an electron beam etching method that improves the resolution of AFM images. This method results in AFM images comparable to those obtained with the transmission electron microscope (TEM). Ultrathin tissue sections embedded in epoxy resin were observed before and after the treatment with electron beam radiation. Before electron beam treatment, epithelial structures such as the microvilli surface, dendritic processes, the supporting cell layers and the neuronal cell layers were all visible using the AFM. However, only a few subcellular structures could also be resolved. The AFM images were not as clear as those obtained with the TEM. After electron beam treatment, however, the resolution of AFM images was greatly improved. Most of the subcellular structures observed in TEM images, including the inner membrane of mitochondria, ciliary-structure precursor body, junctional complexes between the neurons and supporting cells, and individual microvilli were now visible in the AFM images. The electron beam treatment appeared to melt the embedding resin, bringing subcellular structures into high relief. The result of this study suggests that electron beam etching of histological samples may provide a new method for the study of subcellular structure using the AFM.     

基于AFM的化学机械抛光磨粒模拟研究

当前的化学机械抛光(CMP)磨损模型中大多数都缺少微观试验数据的支持。为进步揭示CMP中纳米磨粒对材料表面的磨损机制,提出了采用原子力显微镜(AFM)来模拟CMP中的单个磨粒的试验方案,并验证该模拟试验方案的可行性。结果表明:采用AFM探针来模拟CMP过程中单个磨粒对芯片表面的磨损与相互作用的试验方案是完全可行的;可以通过AFM探针对芯片表面的相互作用与磨损,模拟得出单个磨粒对芯片表面的作用与磨损状况,并可以在此微观试验数据的基础上建立起新的CMP磨损模型。     

Surface profile measurement of a sinusoidal grid using an atomic force microscope on a diamond turning machine

This paper describes the surface profile measurement of a XY-grid workpiece with sinusoidal microstructures using an atomic force microscope (AFM) on a diamond turning machine. The sinusoidal micro-structures, which are fabricated on an aluminum plate by fast tool servo-assisted diamond turning, are a superposition of periodic sine-waves along the X- and Y-directions (wavelength (XY): 150 μm, amplitude (Z): 0.25 μm). A linear encoder with a resolution of 0.5 nm is integrated into the AFM-head for accurate measurement of the Z-directional profile height in the presence of noise associated with the diamond turning machine. The spindle and the X-slide of the machine are employed to spirally scan the AFM-head over the sinusoidal grid workpiece. Experiments fabricating and measuring the sinusoidal grid workpiece are carried out after accurate alignment of the AFM cantilever tip with the spindle centerline.     

Nano-mechanical and tribological characteristics of ultra-thin amorphous carbon film investigated by afm

The mechanical as well as tribological characteristics of coating films as thin as a few nm become more crucial as applications in micro-systems grow. Especially, the amorphous carbon film has a potential to be used as a protective layer for micro-systems. In this work, quantitative evaluation of nano-indentation, scratching, and wear tests were performed on the 7nm thick amorphous carbon film using an Atomic Force Microscope (AFM). It was shown that AFM-based nano-indentation using a diamond coated tip can be feasibly utilized for mechanical characterization of ultra-thin films. Also, it was found that the critical load where the failure of the carbon film occurred was about 18μN by the ramp load scratch test. Finally, the wear experimental results showed that the quantitative wear rate of the carbon film ranged 10^-9~10^-8 mm³/N cycle. These experimental methods can be effectively utilized for a better understanding the mechanical and tribological characteristics at the nano-scale.     

用计量型AFM对一维纳米基准栅的标定及不确定度估计

利用轻敲模式的计量型AFM对公称栅距为240nm一维基准样板进行了标定,在充分分析AFM的结构和特性、测量过程、数据处理的基础上,得到了基准栅的平均栅距估计值和扩展不确定度。通过全面的不确定度分析,估计值的扩展不确定度达到了亚纳米量级。该不确定度分析表明,对于纳米量级测量,不确定度估计不仅需要全面掌握测量仪器、测量过程中各种测量不确定因素的影响,还需要考虑和估计常规测量过程中可以忽略的二次误差的影响。