Contact mechanics and tip shape in AFM-based nanomechanical measurements

Kopycinska-Müller, Malgorzata; Geiss, Roy H.; Hurley, Donna C.

doi:10.1016/j.ultramic.2005.12.006

Cited by 143 publications

(96 citation statements)

References 24 publications

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“…From their research work with similar tip chemistry, the surface density of protein attached to the probe tip was determined and calibrated by a sensitive high-resolution fluorescence imaging method and enzyme chip assay, which showed about 1,500–2,000 molecules per square micron. This molecular surface density translates to less than ten peptide molecules attached to AFM tip, which has an estimated surface area from Hertzian model (the simplest contact-mechanics model to use in AFM-based techniques)32 of ~ 6,000 nm 2 in our case (surface area of hemi-spherical AFM tip end = 2πR 2 ; R~32 nm).…”

Section: Experimental Methodsmentioning

confidence: 99%

Correlation between Desorption Force Measured by Atomic Force Microscopy and Adsorption Free Energy Measured by Surface Plasmon Resonance Spectroscopy for Peptide−Surface Interactions

Wei¹,

Latour²

2010

Langmuir

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Surface Plasmon resonance (SPR) spectroscopy is a useful technique for thermodynamically characterizing peptide-surface interactions; however, its usefulness is limited to the types of surfaces that can readily be formed as thin layers in nanometer scale on metallic biosensor substrates. Atomic force microscopy (AFM), on the other hand, can be used with any microscopically flat surface, thus making it more versatile for studying peptide-surface interactions. AFM, however, has the drawback of data interpretation due to questions regarding peptide-to-probe-tip density. This problem could be overcome if results from a standardized AFM method could be correlated with SPR results for a similar set of peptide-surface interactions so that AFM studies using the standardized method could be extended to characterize peptide-surface interactions for surfaces that are not amenable for characterization by SPR. In this paper, we present the development and application of an AFM method to measure adsorption forces for host-guest peptides sequence on surfaces consisting of alkanethiol self-assembled monolayers (SAMs) with different functionality. The results from these studies show that a linear correlation exists between these data and the adsorption free energy (ΔG°a ds ) values associated with a similar set of peptide-surface systems available from SPR measurements. These methods will be extremely useful to thermodynamically characterize the adsorption behavior for peptides on a much broader range of surfaces than can be used with SPR to provide information related to understanding protein adsorption behavior to these surfaces and to provide an experimental database that can be used for the evaluation, modification, and validation of force field parameters that are needed to accurately represent protein adsorption behavior for molecular simulations.

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Section: Experimental Methodsmentioning

confidence: 99%

Correlation between Desorption Force Measured by Atomic Force Microscopy and Adsorption Free Energy Measured by Surface Plasmon Resonance Spectroscopy for Peptide−Surface Interactions

Wei¹,

Latour²

2010

Langmuir

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“…24 With few exceptions, tip shape calibration has not yet become routine in AFM-based measurements. 25,26 In addition, tip state often changes in STM and AFM, 27 requiring the development of rapid characterization methods. Therefore, of interest are SPM techniques in which this image formation mechanism is such that the signal does not depend on the contact area, either due to fundamental physics of tip-surface interactions or because the contact area is confined to single atom or molecule.…”

Section: Stm Afm Pfmmentioning

confidence: 99%

Electromechanical detection in scanning probe microscopy: Tip models and materials contrast

Eliseev

Kalinin

Jesse

et al. 2007

Journal of Applied Physics

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The rapid development of nanoscience and nanotechnology in the last two decades was stimulated by the emergence of scanning probe microscopy (SPM) techniques capable of accessing local material properties, including transport, mechanical, and electromechanical behavior on the nanoscale. Here, we analyze the general principles of electromechanical probing by piezoresponse force microscopy (PFM), a scanning probe technique applicable to a broad range of piezoelectric and ferroelectric materials. The physics of image formation in PFM is compared to Scanning Tunneling Microscopy and Atomic Force Microscopy in terms of the tensorial nature of excitation and the detection signals and signal dependence on the tipsurface contact area. It is shown that its insensitivity to contact area, capability for vector detection, and strong orientational dependence render this technique a distinct class of SPM.The relationship between vertical and lateral PFM signals and material properties are derived analytically for two cases: transversally-isotropic piezoelectric materials in the limit of weak elastic anisotropy, and anisotropic piezoelectric materials in the limit of weak elastic and dielectric anisotropies. The integral representations for PFM response for fully anisotropic material are also obtained. The image formation mechanism for conventional (e.g., sphere and cone) and multipole tips corresponding to emerging shielded and strip-line type probes are analyzed. Resolution limits in PFM and possible applications for orientation imaging on the nanoscale and molecular resolution imaging are discussed.

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“…However, in case of a flat punch, a c = R and the maximum pressure will be less than that calculated from the spherical tip for the same R. In reality, the shape of the AFM tip is found to be in between a sphere and a flat punch [49] and hence the maximum pressure may be expected to be less than that predicted using Eqs. (6) and (7).…”

Section: Methodsmentioning

confidence: 81%

Elasticity mapping of precipitates in nickel-base superalloys using atomic force acoustic microscopy

2016

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The paper reports mapping of elastic properties of various precipitates such as c 0 , d, and carbides in nickel-base superalloys. Atomic force acoustic microscopy is used to measure the elastic properties with a lateral resolution of better than 100 nm in polycrystalline alloy 625 and directionally solidified alloy CM247A. A novel approach of simultaneous acquisition of two contact resonances and using the isotropic indentation modulus of matrix in every scan line as reference is used to circumvent the effect of change in tip condition while mapping elastic properties. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy is performed to identify the precipitates and their compositions. Carbides exhibited highest modulus followed by d precipitates, c 0 and c matrix, respectively. It is demonstrated that due to the close-packed orientation relationships of precipitates with the matrix, the modulus of a precipitate measured by the methodology described in this study is not affected by the orientation of individual grain in which the measurement is made.

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Contact mechanics and tip shape in AFM-based nanomechanical measurements

Cited by 143 publications

References 24 publications

Correlation between Desorption Force Measured by Atomic Force Microscopy and Adsorption Free Energy Measured by Surface Plasmon Resonance Spectroscopy for Peptide−Surface Interactions

Correlation between Desorption Force Measured by Atomic Force Microscopy and Adsorption Free Energy Measured by Surface Plasmon Resonance Spectroscopy for Peptide−Surface Interactions

Electromechanical detection in scanning probe microscopy: Tip models and materials contrast

Elasticity mapping of precipitates in nickel-base superalloys using atomic force acoustic microscopy

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