The surface microtopography of hematite over the course of dissolution in oxalic and citric acids was examined by in-situ and ex-situ atomic-force microscopy. In-situ imaging of the basal-plane surface of a centimeter-scale natural hematite sample immersed in 2 mM citric acid demonstrated that the basal-plane surface was relatively unreactive; rather, dissolution occurred along step edges and via etch-pit formation. Ex-situ imaging of synthetic hematite particles following batch dissolution in 1 mM oxalic acid showed similar dissolution features on basal-plane surfaces; in addition, etching along particle edges was apparent. The presence of etch features is consistent with a surface-controlled dissolution reaction. The results are in agreement with previous investigations suggesting that the basal-plane surface is relatively unreactive with respect to ligand exchange. Both in-situ and ex-situ imaging of particle surfaces can provide valuable information on the roles of surface structures and microtopographic features in mineral dissolution.

Tumors have posed a serious threat to human life and health. Researchers can determine whether or not cells are cancerous, whether the cancer cells are invasive or metastatic, and what the effects of drugs are on cancer cells by the physical properties such as hardness, adhesion, and Young's modulus. The atomic force microscope (AFM) has emerged as a key important tool for biomechanics research on tumor cells due to its ability to image and collect force spectroscopy information of biological samples with nano-level spatial resolution and under near-physiological conditions. This article reviews the existing results of the study of cancer cells with AFM. The main foci are the operating principle of AFM and research advances in mechanical property measurement, ultra-microtopography, and molecular recognition of tumor cells, which allows us to outline what we do know it in a systematic way and to summarize and to discuss future directions.

Over the past three decades, atomic force microscopy (AFM) has undergone a series of design changes to attain a flat XY scan and stable non-contact mode in ambient atmosphere. AFM has evolved into an ideal method for non-destructive scanning of samples with longer probe tip life, high accuracy, repeatability, and automation. Together with self-optimizing algorithms for scan parameters in the non-contact mode, AFM can become as widely adopted as other microscopies such as optical or scanning electron microscopy (SEM). Even full automation of AFM probe tip exchange is now possible with probe type recognition software and laser beam alignment on the cantilever and position-sensitive photo diode (PSPD). By separating the optics stage from the Z stage, an AFM system can be made with low mechanical noise and improved optical vision.

The aim of this paper is to determine the effects of forces exerted on the cantilever probe tip of an atomic force microscope (AFM). These forces vary according to the separation distance between the probe tip and the surface of the sample being examined. Hence, at a distance away from the surface (farther than don), these forces have an attractive nature and are of Van der Waals type, and when the probe tip is situated in the range of a0≤dts≤don, the capillary force is added to the Van der Waals force. At a distance of dts≤a0, the Van der Waals and capillary forces remain constant at intermolecular distances, and the contact repulsive force repels the probe tip from the surface of sample. The capillary force emerges due to the contact of thin water films with a thickness of hc which have accumulated on the sample and probe. Under environmental conditions a layer of water or hydrocarbon often forms between the probe tip and sample. The capillary meniscus can grow until the rate of evaporation equals the rate of condensation. For each of the above forces, different models are presented. The smoothness or roughness of the surfaces and the geometry of the cantilever tip have a significant effect on the modeling of forces applied on the probe tip. Van der Waals and the repulsive forces are considered to be the same in all the simulations, and only the capillary force is altered in order to evaluate the role of this force in the AFM-based modeling. Therefore, in view of the remarkable advantages of the piezoelectric microcantilever and also the extensive applications of the tapping mode, we investigate vibrational motion of the piezoelectric microcantilever in the tapping mode. The cantilever mentioned is entirely covered by two piezoelectric layers that carry out both the actuation of the probe tip and the measuringof its position.

The resonant frequency and sensitivity of an atomic force microscope (AFM) with an assembled cantilever probe (ACP) is analyzed utilizing strain gradient theory, and then the governing equation and boundary conditions are derived by a combination of the basic equations of strain gradient theory and Hamilton’s principle. The resonant frequency and sensitivity of the proposed AFM microcantilever are then obtained numerically. The proposed ACP includes a horizontal cantilever, two vertical extensions, and two tips located at the free ends of the extensions that form a caliper. As one of the extensions is located between the clamped and free ends of the AFM microcantilever, the cantilever is modeled as two beams. The results of the current model are compared with those evaluated by both modified couple stress and classical beam theories. The difference in results evaluated by the strain gradient theory and those predicted by the couple stress and classical beam theories is significant, especially when the microcantilever thickness is approximately the same as the material length-scale parameters. The results also indicate that at the low values of contact stiffness, scanning in the higher cantilever modes decrease the accuracy of the proposed AFM ACP.

We describe an improved experimental approach for characterizing the elastic modulus and hardness of single microfibers through instrumented indentation. A sample mounting technique on a curved surface is presented that ensures contact between an unmodified fiber and substrate. The indentation analysis considers three separate corrections to the well-known Oliver and Pharr method: (i) overestimation of the projected contact area due to sample curvature, (ii) overestimation of projected contact area due to substrate curvature, and (iii) underestimation of fiber stiffness due to the structural compliance of the sample. The method is applied to four types of high performance ballistic fibers: KM2 Plus, Twaron, AuTx, and Dyneema; the results are presented according to both the modified analyses as well as the standard Oliver and Pharr analysis. The modified analyses resulted in an increase in the elastic modulus and hardness of up to 35 and 60%, respectively, compared to the Oliver–Pharr method. The technique has the potential to be applied to single microfilaments under various environmental conditions that may otherwise be compromised by traditional fiber mounting methods.

Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.

CuInS2 thin films with thickness ranging from 196 to 1000 nm were prepared from a source containing CuInS2 nanocrystals by using thermal evaporation method. Annealed films of CuInS2 show the quasi-amorphous to crystalline phase transition, probed through x-ray diffraction (XRD), UV-visible spectrometer, and Raman spectroscopy. From XRD, the tetragonal distortion (η) is found to be ≈1, confirming the arrangement of an extended double lattice structure of chalcopyrite phase. The surface morphology of quasi-amorphous film exhibits a very smooth surface, whereas crystalline film shows a very rough surface of CuInS2 as observed from atomic force microscopy. Crystallite size and rms roughness increase from 23 to 310 nm and from 1.5 to 36.5, respectively, with increasing film thickness as well as with increasing annealing temperature due to the crystallization process. Micro-Raman study evidencing the presence of a strong Raman A1 mode at 303 cm−1, due to the symmetric vibration of anion sublattice of CuInS2 structure. A fundamental band edge is observed in as-deposited quasi-amorphous CuInS2 films, while bulk energy band absorption and excitonic band transition are observed in crystalline films. A sharp drop in both reflectance and transmittance near the energy band gap region is observed in thick films due to a very strong absorption of crystalline phase of CuInS2.

Step height is defined as the vertical spacing between two plane-parallel planes comprising an elevation or an indentation and the substrate. In atomic force microscopy (AFM), there are many algorithms for determining feature dimensions such as step height and width. One common problem of many algorithms is the difficulty for users to accurately determine the corner positions needed to properly implement the said algorithms. A new algorithm based on ISO 5436-1 is proposed that determines the necessary corner positions along with two examples illustrating the implementation of this algorithm. We propose calling this new method the determinant method. Since the corner positions are automatically decided, feature dimensions such as step height of an AFM image are easily determined. Comparative experiments carried out to compare the step height measurement using this algorithm and the SPIP software from Image Metrology show encouraging results.

Imaging of latex particles, especially those with low glass transition temperature (Tg) has been a challenging issue. Different sample preparation methods for characterization of the morphology of a poly(n-butyl acrylate)/polystyrene two-phase latex are discussed and compared in this study. A method via hydroxyethyl cellulose embedding combined with ruthenium tetraoxide (RuO4) staining for scanning transmission electron microscope (STEM) observation is developed. By using this method, the spherical shape of latex particles can be maintained without deformation. The degree of incorporation of RuO4 into latex particles and cellulose matrix is different, which makes latex particles readily identifiable from cellulose matrix under STEM. A series of latexes with different structures such as copolymer latex and organic-inorganic hybrid latex were also successfully investigated by this method. The results indicate this specimen preparation method can be applied to study the morphology of a wide range of latex systems.

Atomic force microscopy (AFM) is one of the most sensitive tools for nanoscale imaging. As such, it is very sensitive to external noise sources that can affect the quality of collected data. The intensity of the disturbance depends on the noise source and the mode of operation. In some cases, the internal noise from commercial AFM controllers can be significant and difficult to remove. Thus, a new method based on spectrum analysis of the scanned images is proposed to reduce harmonic disturbances. The proposal is a post-processing method and can be applied at any time after measurements. This article includes a few methods of harmonic cancellation (e.g., median filtering, wavelet denoising, Savitzky-Golay smoothing) and compares their effectiveness. The proposed method, based on Fourier transform of the scanned images, was more productive than the other methods mentioned before. The presented data were achieved for images of conductive layers taken in a contact AFM mode.

The atomic force microscopes (AFM) images are obtained by keeping the bending of the cantilever unchanged in contact mode. However, it is found that changes in the tip-sample angle during parallel scan result in error in the topographic image. It is also discovered that measurement results obtained in the blind scan region contained large errors. In contrast, regions opposite the blind scan region gave more reliable result. To eliminate this topographic error caused by change in the tip-sample angle, a new operating method with lateral scan is utilized in AFM. Comparative experiments have been performed, and the results show that the error could be eliminated or decreased by using the operating method.

Atomic force microscopy (AFM) is a specialised form of scanning probe microscopy, which was invented by Binnig and colleagues in 1986. Since then, AFM has been increasingly used to study biomedical problems. Because of its high resolution, AFM has been used to examine the topography or shape of surfaces, such as during the molecular imaging of proteins. This, combined with the ability to operate under known force regimes, makes AFM technology particularly useful for measuring intermolecular bond forces and assessing the mechanical properties of biological materials. Many of the constraints (e.g. complex instrumentation, slow acquisition speeds and poor vertical range) that previously limited the use of AFM in cell biology are now beginning to be resolved. Technological advances will enable AFM to challenge both confocal laser scanning microscopy and scanning electron microscopy as a method for carrying out three-dimensional imaging. Its use as both a precise micro-manipulator and a measurement tool will probably result in many novel and exciting applications in the future. In this article, we have reviewed some of the current biological applications of AFM, and illustrated these applications using studies of the cell biology of bone and integrin-mediated adhesion.

Measuring the changing thickness of a thin film, without a reference, using an atomic force microscope (AFM) is problematic. Here, we report a method for measuring film thickness based on in situ monitoring of surface roughness of films as their thickness changes. For example, in situ AFM roughness measurements have been performed on alloy film electrodes on rigid substrates as they react with lithium electrochemically. The addition (or removal) of lithium to (or from) the alloy causes the latter to expand (or contract) reversibly in the direction perpendicular to the substrate and, in principle, the change in the overall height of these materials is directly proportional to the change in roughness. If the substrate on which the film is deposited is not perfectly smooth, a correction to the direct proportionality is needed and this is also discussed.