Nanomanipulation and environmental nanotechnology

• Enrico Gnecco,
• Andre Schirmeisen,
• Carlos M. Pina and
• Udo Becker

Beilstein J. Nanotechnol. 2014, 5, 2079–2080, doi:10.3762/bjnano.5.216

• processes. For example, the photocatalytic degradation of pollutants can be interpreted using density functional theory. On a different scale, AFM measurements in liquid environments can be supported by advanced contact mechanics models including the squeeze-out of wetting fluids. Adhesion of fluorite

Equilibrium states and stability of pre-tensioned adhesive tapes

• Carmine Putignano,
• Luciano Afferrante,
• Luigi Mangialardi and
• Giuseppe Carbone

Beilstein J. Nanotechnol. 2014, 5, 1725–1731, doi:10.3762/bjnano.5.182

• theoretical investigations about rough contact mechanics [25][26][27][28][29], the role of roughness in this kind of systems is not yet well understood. Furthermore, viscoelasticity, which entails prominent effects in terms of friction and contact anisotropy [30][31], has not yet been included in analytical

From sticky to slippery: Biological and biologically-inspired adhesion and friction

• Stanislav N. Gorb and
• Kerstin Koch

Beilstein J. Nanotechnol. 2014, 5, 1450–1451, doi:10.3762/bjnano.5.157

• theoretical studies which range from insect adhesion, bacterial adhesion and skin friction to artificial biomimetic systems, e.g., snake-skin inspired polymer patterns or gecko tape. The Thematic Series does not attempt to give a comprehensive overview of the emerging field of biological contact mechanics

Surface topography and contact mechanics of dry and wet human skin

• Alexander E. Kovalev,
• Kirstin Dening,
• Bo N. J. Persson and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 1341–1348, doi:10.3762/bjnano.5.147

• topography of the human wrist skin is studied by using optical and atomic force microscopy (AFM) methods. By using these techniques the surface roughness power spectrum is obtained. The Persson contact mechanics theory is used to calculate the contact area for different magnifications, for the dry and wet

• defined only when a combination of both AFM and optical methods is used for power spectrum calculation. Keywords: contact mechanics; interface fluid; roughness power spectrum; skin tribology; Introduction The tribology of human skin is of great importance in sports, medicine, and cosmetics [1][2]. It is

• ]. In a first approximation, a two layers model, with a thin stiff layer on top of a thick soft layer, is sufficient for a satisfactory description of the contact mechanics between the skin and the indentor. The change of skin morphology and elastic modulus in the wet state contributes to the high

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• , feature sizes, shapes and patterns, which have been previously attributed by others to the competing effects of membrane functionality and contact mechanics on the cantilever response [19]. In cases in which the mechanics of the subsurface are of interest, it is necessary to operate the AFM in a way that

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

• Lars Heepe,
• Alexander E. Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

• in predominantly liquid environments. Keywords: bio-inspired; biomimetic; cavitation; contact mechanics; gecko; interface; negative pressure; pull-off; surface; tribology; Introduction During the past two decades, bio-inspired microstructured adhesives became a new class of adhesive materials with

Single-asperity contact mechanics with positive and negative work of adhesion: Influence of finite-range interactions and a continuum description for the squeeze-out of wetting fluids

• Martin H. Müser

Beilstein J. Nanotechnol. 2014, 5, 419–437, doi:10.3762/bjnano.5.50

• Martin H. Muser Jülich Supercomputing Centre, FZ Jülich, 52428 Jülich, Germany 10.3762/bjnano.5.50 Abstract In this work, single-asperity contact mechanics is investigated for positive and negative work of adhesion Δγ. In the latter case, finite-range repulsion acts in addition to hard-wall

• of the finite-range attraction. The results can benefit the interpretation of atomic force microscopy in liquid environments and the modeling of multi-asperity contacts. Keywords: cohesive zone model; contact mechanics; environmental; fluid squeeze-out; nanomechanics; single-asperity contacts

• ; Introduction The continuum description of single-asperity contact mechanics has received much attention in the last few decades. This is in large parts because it describes force-displacement curves rather accurately down to nanometer scales relevant to atomic force microscopy (AFM) [1][2][3]. The

Manipulation of nanoparticles of different shapes inside a scanning electron microscope

• Boris Polyakov,
• Sergei Vlassov,
• Leonid M. Dorogin,
• Jelena Butikova,
• Mikk Antsov,
• Sven Oras,
• Rünno Lõhmus and
• Ilmar Kink

Beilstein J. Nanotechnol. 2014, 5, 133–140, doi:10.3762/bjnano.5.13

• and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. Keywords: contact mechanics; nanomanipulation; nanoparticles; nanotribology; scanning electron microscopy (SEM); Introduction The manipulation of nanoparticles (NPs) is a powerful

• of the contact: where Θ is the contact angle for Ag/SiO2 interface. As described previously [20], for sphere-like NPs contact mechanics (adhesive contact approach) must be applied. The contact area is typically calculated on the basis of continuum elasticity models for deformable spheres such as the

Peak forces and lateral resolution in amplitude modulation force microscopy in liquid

• Horacio V. Guzman and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2013, 4, 852–859, doi:10.3762/bjnano.4.96

• tip motion in liquid. The forces are obtained by using two contact mechanics models, Hertz and Tatara. We present a comparison between the numerical simulations and three analytical models for a wide variety of probe and operational parameters. In general, the forces derived from analytical

• expressions are not in good quantitative agreement with the simulations when the Young modulus and the set-point amplitude are varied. The only exception is the parametrized approximation that matches the results given by Hertz contact mechanics for soft materials and small free amplitudes. We also study the

• relatively rigid (2 GPa) materials for two different models of contact mechanics, namely Hertz [29] and Tatara [30][31][32]. We also provide a comparison between the numerical simulations and three analytical expressions [21][33][34]. The dependence of the peak force on a wide range of tip–microcantilever

Dynamic nanoindentation by instrumented nanoindentation and force microscopy: a comparative review

• Sidney R. Cohen and
• Estelle Kalfon-Cohen

Beilstein J. Nanotechnol. 2013, 4, 815–833, doi:10.3762/bjnano.4.93

• the overall force behavior at the nanoscale. Several groups considered the effects of adhesion under various contact mechanics models in the 1970s [9][10][11][12][13]. These models analyze the changing contact shapes and stresses that occur when the surface energy and the adhesive forces in the

• ” in the curve (as shown in Figure 3) and, in extreme cases, to an apparent negative stiffness. This phenomenon will depend on the rate of change of the force. Computational approaches exist that modify the Sneddon contact mechanics model to remove the time-dependent effects of viscoelastic materials

High-resolution nanomechanical analysis of suspended electrospun silk fibers with the torsional harmonic atomic force microscope

• Mark Cronin-Golomb and
• Ozgur Sahin

Beilstein J. Nanotechnol. 2013, 4, 243–248, doi:10.3762/bjnano.4.25

• force–distance curves to parameters representing the material properties. Although contact-mechanics models can be used for a wide variety of polymer composites, block-copolymers, and biomaterials [27][28][29][30][31][32][33][34], these models are not applicable to materials with complex geometries. For

• worth noting that all these models assume that the displacement of the fiber at the nodes is zero, which would result in an effectively infinite spring constant at these locations. In our experiments, the spring constant at the nodes are finite and determined by both the tip–fiber contact-mechanics and

• radius, the pinned end model cannot provide an elastic modulus value that falls in a plausible range (<15 GPa). Conclusion In this paper we have investigated the mechanical behavior of electrospun silk fibers whose geometry does not allow the straightforward use of contact-mechanics models. We used

Mapping mechanical properties of organic thin films by force-modulation microscopy in aqueous media

• Jianming Zhang,
• Zehra Parlak,
• Carleen M. Bowers,
• Terrence Oas and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 464–474, doi:10.3762/bjnano.3.53

• properties of self-assembled monolayers and end-tethered protein thin films in aqueous media. Furthermore, we describe a simple analysis of the contact mechanics that enables the selection of FMM imaging parameters and thus yields a reliable interpretation of the FMM image contrast. Keywords: acoustic

• analysis by selecting an appropriate contact mechanics model, such as the Johnson–Kendall–Roberts (JKR) or the Derjaguin–Muller–Toporov (DMT) model [41][45]. Although contact deformation and force have a nonlinear relationship in the Hertzian contact model, this model can be linearized for a small force

• , while the adhesion force on the protein surface is within the noise level of the measurement. This justifies the use of a Hertzian contact mechanics model, as done here. Our approach currently does not capture the viscoelasticity of the protein or the response of the cantilever to a viscoelastic contact

Theoretical study of the frequency shift in bimodal FM-AFM by fractional calculus

• Elena T. Herruzo and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2012, 3, 198–206, doi:10.3762/bjnano.3.22

• of the interaction force. The approximations are also valid for two different types of forces, namely Lennard-Jones interactions and DMT contact-mechanics forces. We conclude that the fractional-calculus approach is well suited to describe bimodal frequency modulation AFM experiments, which are

Review of "Contact Mechanics and Friction: Physical Principles and Applications" by Valentin L. Popov

• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2011, 2, 57–58, doi:10.3762/bjnano.2.7

• Stanislav N. Gorb Department of Functional Morphology and Biomechanics, Zoological Institute at the University of Kiel, Am Botanischen Garten 1–9, D-24098 Kiel, Germany 10.3762/bjnano.2.7 Keywords: adhesion; capillarity; contact mechanics; continuum mechanics; friction; lubrication; materials

• science; structural mechanics; system dynamics; tribology; Popov, V. L. Contact Mechanics and Friction: Physical Principles and Applications, 1st ed. Springer-Verlag: Berlin, Heidelberg, 2010. XV, 362 pages, ISBN 978-3-642-10802-0 (Print), 978-3-642-10803-7 (Online). doi:10.1007/978-3-642-10803-7 The

• book “Contact Mechanics and Friction: Physical Principles and Applications” is written by a theoretical physicist but from the point of view of an engineer. It covers an amazingly broad spectrum of topics ranging from atomic scale friction, continuum and structural mechanics, materials science

The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

• W. Merlijn van Spengen,
• Viviane Turq and
• Joost W. M. Frenken

Beilstein J. Nanotechnol. 2010, 1, 163–171, doi:10.3762/bjnano.1.20

• ] using a dedicated contact mechanics model. This paper first reviews typical MEMS friction measurements with our fully MEMS-based tribometer, showing the irregular, but repeatable, stick-slip motion of MEMS surfaces in contact. Then we extend the common Prandtl–Tomlinson model with a stochastic component