Displacement atomic force microscope

A most recent commercial Nano Indenter (Nano Indenter XP (MTS, 2001)) consists of three major components [66] the indenter head, an optical/atomic force microscope, and x-y-z motorized precision table for positioning and transporting the sample between the optical microscopy and indenter (Fig. 28). The load on the indenter is generated using a voice coil in permanent magnet assembly, attached to the top of the indenter column. The displacement of the indenter is measured using a three plate capacitive displacement sensor. At the bottom of the indenter rod, a three-sided... 

Abstract. Quantitative measurements of lateral force required for displacement of SWNTs bundle on the surface of highly oriented pyrolytic graphite with the help of atomic force microscope (AFM) were performed in real time . New method of quantitative calibration of lateral forces was used for interpretation results of lateral force microscopy (LFM). It allows us to receive numerical values of adhesion force of bundle to substrate easy and without specific equipment. 

Figure 2.35. Examples of indentation processes to determine surface hardness. Shown are (a) Vickers indentation on a SiC-BN composite, (b) atomic force microscope images of the nanoindentation of a silver nanowire, and (c) height profile and load-displacement curve for an indent on the nanowire. Reproduced with permission fromNanoLett. 2003, 3(11), 1495. Copyright 2003 American Chemical Society.

Figures Atomic force microscope image of a carbon nanotube deposited on a filtration membrane for measuring the displacement-force curves for the evaluation of the...

So how do small molecules competitively displace proteins This can be answered by visualizing the structural changes that occur during displacement using probe microscopes such as the atomic force microscope (AFM). Understanding the interactions between proteins and small molecules is of importance, but is not the whole story. In food systems there will almost always be mixtures of proteins present at the interface, and we need to know what sorts of structures are formed by mixtures of proteins and how they resist displacement. We need to be able to recognize and locate individual proteins. 

Modification of the atomic force microscope with feedback loops enabled force-extension curves for individual polysaccharide molecules to be measured under constantly increasing force (rather than constant displacement), in a nanoscale version of the INSTRON tester for measuring paper strength. ... 

Fig. 7. Atomic force microscope (AFM) images of an RDX crystal, (a) A perfect crystal lattice is observed on a smooth cleavage plane surface, (b) After drop-hammer impact from a height well below H50, individual molecules are displaced and reoriented. Reproduced with permission from ref. [63].

Indentation testing can also be performed with an atomic force microscope, which has pico-Newton force and angstrom displacement resolution at the lower end the draw back is that the dynamic displacement range is limited to several microns. Moreover, on older systems, the control software, as well as that needed for test interpretation, may not be readily available. 

Nanoindentation is a powerful technique because the shape of the load-displacement curve can be used to identify effects such as phase transformations, cracking, and film delamination dining indentation. It is also important in studying the mechanical properties of nanomaterials, such as carbon nanotubes. There is reference now to a picoindenter, which is a combination of a nanoindenter and an atomic force microscope (AFM). 

The actual trend in hardness testing is to use the nanoindentation instruments in conjimction with atomic force microscopes (45). Load-displacement measurements are used to derive hardness and elastic modulus data while the atomic force microscope yields additional topographic information of the indentation area. Measurements at depths of 1 nm can be performed. 

Friedt JM, Choi KH, Francis L, Campitelli A (2002) Simultaneous atomic force microscope and quartz crystal microbalance measurements interactions and displacement field of a quartz crystal microbalance. Jpn J Appl Phys 1 41(6A) 3974-3977... 

An atomic force microscope is used to stuviscoelastic state at the temperature of experiment. It is shown that, during the preliminary phase of friction and before the transition to the sliding regime, the contact area remains nearly constant. This allows for a determination of the relaxation and of the complex modulus of the material. A good agreement is found between moduli measured by this method and macroscopically determined ones. The position of the transition is seen to scale with the characteristic size of the contact area but it does not depend on the displacement velocity. Finally, a transient stick-slip regime is observed before the sliding steady state is reached. 

Figure 10 Force versus displacement curves recorded between functionalized atomic force microscope cantilever probes and surfeces. The adhesive interactions are strong for like-like interactions (COOH-COOH and CH3-CH3) but weak for interaction between unlike functional groups (COOH-CH3). Noy A, Frisbie CD and Lieber CM, unpublished results.

Many techniques have been developed to measure the Young s modulus and the stress of the mesoscopic systems [12, 13]. Besides the traditional Vickers microhardness test, techniques mostly used for nanostructures are tensile test using an atomic force microscope (AFM) cantilever, a nanotensile tester, a transmission electron microscopy (TEM)-based tensile tester, an AFM nanoindenter, an AFM three-point bending tester, an AFM wire free-end displacement tester, an AFM elastic-plastic indentation tester, and a nanoindentation tester. Surface acoustic waves (SAWs), ultrasonic waves, atomic force acoustic microscopy (AFAM), and electric field-induced oscillations in AFM and in TEM are also used. Comparatively, the methods of SAWs, ultrasonic waves, field-induced oscillations, and an AFAM could minimize the artifacts because of their nondestructive nature though these techniques collect statistic information from responses of all the chemical bonds involved [14]. 

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