共查询到20条相似文献,搜索用时 156 毫秒
1.
A novel sample holder that allows atomic force microscopy (AFM) to be performed on transmission electron microscope (TEM) grids is described. Consequently, AFM and TEM images were repeatedly obtained on exactly the same sample area. For both techniques, a thin carbon film was used as the imaging substrate. Although these techniques have been previously used in conjunction, AFM and TEM images on exactly the same area have not been repeatedly obtained for any system. Correlation of AFM and TEM images is useful for work where the three‐dimensional topographical information provided by the AFM could be used to better interpret the two‐dimensional images provided by the TEM and vice versa. To demonstrate the applicability of such correlation, new results pertaining to a fibrillar collagen system are summarized. 相似文献
2.
Winfried Wiegrbe Martin Nonnenmacher Reinhard Guckenberger Olaf Wolter 《Journal of microscopy》1991,163(1):79-84
The protein surface layer of the bacterium Deinococcus radiodurans (HPI layer) was examined with an atomic force microscope (AFM). The measurements on the air-dried, but still hydrated layer were performed in the attractive imaging mode in which the forces between tip and sample are much smaller than in AFM in the repulsive mode or in scanning tunnelling microscopy (STM). The results are compared with STM and transmission electron microscopy (TEM) data. 相似文献
3.
A novel sample holder that enables atomic force microscopy (AFM) tips to be mounted inside a scanning electron microscopy (SEM) for the purpose of characterizing the AFM tips is described. The holder provides quick and easy handling of tips by using a spring clip to hold them in place. The holder can accommodate two tips simultaneously in two perpendicular orientations, allowing both top and side view imaging of the tips by the SEM. 相似文献
4.
《Measurement》2016
We present a remotely-controlled device for sample stretching, designed for use with atomic force microscopy (AFM) and providing electrical connection to the sample. Such a device enables nanoscale investigation of electrical properties of thin gold films deposited on polydimethylsiloxane (PDMS) substrate as a function of the elongation of the structure. Stretching and releasing is remotely controlled with use of a dc actuator. Moreover, the sample is stretched symmetrically, which gives an opportunity to perform AFM scans in the same site without a time-consuming finding procedure. Electrical connections to the sample are also provided, enabling Kelvin probe force microscopy (KPFM) investigations. Additionally, we present results of AFM imaging using the stretching stage. 相似文献
5.
Matsko NB 《Ultramicroscopy》2007,107(2-3):95-105
We demonstrate that atomic force microscopy represents a powerful tool for the estimation of structural preservation of biological samples embedded in epoxy resin, in terms of their macromolecular distribution and architecture. The comparison of atomic force microscopy (AFM) and transmission electron microscopy (TEM) images of a biosample (Caenorhabditis elegans) prepared following to different types of freeze-substitution protocols (conventional OsO4 fixation, epoxy fixation) led to the conclusion that high TEM stainability of the sample results from a low macromolecular density of the cellular matrix. We propose a novel procedure aimed to obtain AFM and TEM images of the same particular organelle, which strongly facilitates AFM image interpretation and reveals new ultrastructural aspects (mainly protein arrangement) of a biosample in addition to TEM data. 相似文献
6.
This paper presents a novel estimation scheme to calculate the probe–sample separation in atomic force microscopy (AFM). The AFM is capable of measuring the sample topography by using a probe to interact with the sample. The interaction is dominated by the atomic force which is dependent on the probe–sample separation and sample properties. The key to successful AFM applications is accurate sensing and regulation of the probe–sample separation in nanometer scale. Our proposed scheme provides an accurate estimate of the probe–sample separation based on the information of the main sinusoidal and its harmonics. The estimation is shown to have a good performance even when noise is present. 相似文献
7.
With the integration of submicro- and nanoelectrodes into atomic force microscopy (AFM) probes using microfabrication techniques, an elegant approach combining scanning electrochemical microscopy (SECM) with AFM has recently been introduced. Simultaneous contact mode imaging of a micropatterned sample with immobilized enzyme spots and imaging of enzyme activity is shown. In contrast to force spectroscopy the conversion of an enzymatic byproduct is directly detected during AFM imaging and correlated to the activity of the enzyme. 相似文献
8.
Melling M Karimian-Teherani D Mostler S Behnam M Hochmeister S 《Microscopy research and technique》2004,64(1):1-9
A comparative study of atomic force microscopy (AFM) and scanning electron microscopy (SEM) imaging of the healthy human liver parenchyma was carried out to determine the similarities and the differences. In this study, we compared the fine hepatic structures as observed by SEM and AFM. Although AFM revealed such typical hepatic structures as bile canaliculi and hepatocytes, it also showed the location of the nucleus and chromatin granules in rough relief structure, which was not visible by SEM. By contrast, SEM visualized other structures, such as microvilli, the central vein, and collagenous fibers, none of which was visualized by AFM. For better orientation and confirmation of most of the structures imaged by SEM and AFM, Congo Red-stained specimens were also examined. Amyloid deposits in the Disse's spaces were shown especially clearly in these images. The differences between the SEM and AFM images reflected the characteristics of the detection systems and methods used for sample preparation. Our results reveal that more detailed information on hepatic morphology is obtained by exploiting the advantages of both SEM and AFM. 相似文献
9.
Here we demonstrate a new microscopic method that combines atomic force microscopy (AFM) with fluorescence resonance energy transfer (FRET). This method takes advantage of the strong distance dependence in Förster energy transfer between dyes with the appropriate donor/acceptor properties to couple an optical dimension with conventional AFM. This is achieved by attaching an acceptor dye to the end of an AFM tip and exciting a sample bound donor dye through far-field illumination. Energy transfer from the excited donor to the tip immobilized acceptor dye leads to emission in the red whenever there is sufficient overlap between the two dyes. Because of the highly exponential distance dependence in this process, only those dyes located at the apex of the AFM tip, nearest the sample, interact strongly. This limited and highly specific interaction provides a mechanism for obtaining fluorescence contrast with high spatial resolution. Initial results in which 400 nm resolution is obtained through this AFM/FRET imaging technique are reported. Future modifications in the probe design are discussed to further improve both the fluorescence resolution and imaging capabilities of this new technique. 相似文献
10.
11.
Friction forces in the tip–sample contact govern the dynamics of contact mode atomic force microscopy. In ambient conditions typical contact radii between tip and sample are in the order of a few nanometers. In order to account for the large interaction area the dynamics of contact mode atomic force microscope (AFM) is investigated under the assumption of a multi-asperity contact interface between tip and sample. Thus, the kinetic friction force between tip and sample is the product of the real contact area between both solids and the interfacial shear strength. The velocity strengthening of the lateral force is modeled assuming a logarithmic relationship between shear-strength and velocity. Numerical simulations of the system dynamics with this empirical model show the existence of two different regimes in contact mode AFM: steady sliding and stick–slip where the tip undergoes periodically stiction and kinetic friction. The state of the system depends on the scan velocity as well as on the velocity dependence of the interfacial friction force between tip and sample. Already small viscous damping contributions in the tip–sample contact are sufficient to suppress stick–slip oscillations. 相似文献
12.
The technique demonstrated here provides features of both scanning tunnelling microscopy (STM) and atomic force microscopy (AFM). The metallic probe acts to record current variations and sense forces from the same sample area simultaneously. Thus, separate images may be recorded, in registry. The collected data allows real space correlations between some electrical properties and the geometric structure of a sample surface. The same tip is used since the geometry and condition of the tip can effect the data recordings. Platinum alloys, tungsten and graphite tips have been employed successfully. An AFM lever can respond to surface contact forces, within the elastic limits of the sample, while electric current is sensed by the tip of the lever. The usefulness of this experimental procedure is tested here by an application to semiconducting samples of Ag-doped CdTe in air and in paraffin oil media. 相似文献
13.
Drying cells for SEM, AFM and TEM by hexamethyldisilazane: a study on hepatic endothelial cells 总被引:10,自引:0,他引:10
Critical point drying (CPD) is a common method of drying biological specimens for scanning electron microscopy (SEM). Drying by evaporation of hexamethyldisilazane (HMDS) has been described as a good alternative. This method, however, is infrequently used. Therefore, we reassessed HMDS drying. Cultured rat hepatic sinusoidal endothelial cells (LEC), possessing fragile fenestrae and sieve plates, were subjected to CPD and HMDS drying and evaluated in the scanning electron microscope, atomic force microscope (AFM) and transmission electron microscope (TEM). We observed no differences between the two methods regarding cellular ultrastructure. In contrast with CPD, HMDS drying takes only a few minutes, less effort, low costs for chemicals and requires no equipment. We conclude that HMDS-dried specimens have equal quality to CPD ones. Furthermore, the method also proved useful for drying whole-mount cells for TEM and AFM. 相似文献
14.
Milani M Drobne D Tatti F Batani D Poletti G Orsini F Zullini A Zrimec A 《Scanning》2005,27(5):249-253
A novel focused ion beam-based technique is presented for the read-out of microradiographs of Caenorhabditis elegans nematodes generated by soft x-ray contact microscopy (SXCM). In previous studies, the read-out was performed by atomic force microscopy (AFM), but in our work SXCM microradiographs were imaged by scanning ion microscopy (SIM) in a focused ion beam/scanning electron microscope (FIB/SEM). It allows an ad libitum selection of a sample region for gross morphologic to nanometric investigations, with a sequence of imaging and cutting. The FIB/SEM is less sensitive to height variation of the relief, and sectioning makes it possible to analyse the sample further. The SXCM can be coupled to SIM in a more efficient and faster way than to AFM. Scanning ion microscopy is the method of choice for the read-out of microradiographs of small multicellular organisms. 相似文献
15.
To improve the precision of dynamic atomic force microscopy (AFM) using cantilever vibration spectra, a simple but effective method for suppressing spurious response (SR) was developed. The dominant origin of SR was identified to be the bending vibration of the cantilever substrate, by the analysis of the frequency of SR. Although a rigid cover pressing the whole surface of the substrate suppressed SR, the utility was insufficient. Then, a method of enhancing the bending rigidity of the substrate by gluing a rigid plate (clamping plate, CP) to the substrate was developed. This chip can be used with an ordinary cantilever holder, so that the reproducibility of SR suppression when attaching and detaching the cantilever chip to the holder was improved. To verify its utility, the evaluation of a microdevice electrode was performed by ultrasonic atomic force microscopy. The delamination at a submicron depth was visualized and the detailed variation of the delamination was evaluated for the first time using clear resonance spectra. The CP method will particularly contribute to improving dynamic-mode AFM, in which resonance spectra with a low quality factor are used, such as noncontact mode AFM in liquid or contact resonance mode AFM. The effect of the CP can be achieved by fabricating a substrate with a thick plate beforehand. 相似文献
16.
Daniel Platz Erik A. Tholén Carsten Hutter Arndt C. von Bieren David B. Haviland 《Ultramicroscopy》2010
Intermodulation atomic force microscopy (IMAFM) is a dynamic mode of atomic force microscopy (AFM) with two-tone excitation. The oscillating AFM cantilever in close proximity to a surface experiences the nonlinear tip-sample force which mixes the drive tones and generates new frequency components in the cantilever response known as intermodulation products (IMPs). We present a procedure for extracting the phase at each IMP and demonstrate phase images made by recording this phase while scanning. Amplitude and phase images at intermodulation frequencies exhibit enhanced topographic and material contrast. 相似文献
17.
The increased growth in the use of tip-based sensing, manipulations, and fabrication of devices in atomic force microscopy (AFM) necessitates the accurate prediction of the dynamic behavior of the AFM probe. The chip holder, to which the micro-sensing device is attached, and the rest of the AFM system can affect the overall dynamics of the probe. In order to consider these boundary effects, we propose a novel receptance coupling method to mathematically combine the dynamics of the AFM setup and probe, based on the equilibrium and compatibility conditions at the joint. Once the frequency response functions of displacement over force at the tool tip are obtained, the dynamic interaction forces between the tip and the sample in nanoscale can be determined by measuring the probe tip displacement. 相似文献
18.
Frictional effects in atomic force microscopy (AFM) of Langmuir-Blodgett films of 1, 2-dipalmitoyl-snglycero-phosphoglycerol were examined. Height measurements of the Langmuir layers are strongly influenced by the orientation of the cantilevers used in AFM relative to the sample. A simple model is used to describe the frictional effects and to calculate the real height of the monolayers. 相似文献
19.
20.
Se-Hui Jung Jin-Young Park Je-Ok Yoo Incheol Shin Young-Myeong Kim Kwon-Soo Ha 《Ultramicroscopy》2009,109(12):1428-1434
Atomic force microscopy (AFM) is an emerging technique for imaging biological samples at subnanometer resolution; however, the method is not widely used for cell imaging because it is limited to analysis of surface topology. In this study, we demonstrate identification and ultrastructural imaging of microfilaments using new approaches based on AFM. Photodynamic therapy (PDT) with a new chlorin-based photosensitizer DH-II-24 induced cell shrinkage, membrane blebbing, and reorganization of cytoskeletons in bladder cancer J82 cells. We investigated cytoskeletal changes using confocal microscopy and atomic force microscopy. Extracellular filaments formed by PDT were analyzed with a tandem imaging approach based on confocal microscopy and atomic force microscopy. Ultrathin filaments that were not visible by confocal microscopy were identified as microfilaments by on-stage labeling/imaging using atomic force microscopy. Furthermore, ultrastructural imaging revealed that these microfilaments had a stranded helical structure. Thus, these new approaches were useful for ultrastructural imaging of microfilaments at the molecular level, and, moreover, they may help to overcome the current limitations of fluorescence-based microscopy and atomic force microscopy in cell imaging. 相似文献