Sliding Velocity Dependence of Adhesion in a Nanometer-Sized Contact

Noël, Olivier; Mazeran, Pierre‐Emmanuel; Nasrallah, Houssein

doi:10.1103/physrevlett.108.015503

Cited by 37 publications

(32 citation statements)

References 23 publications

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“…Although AFM tip in our experiments constantly moves relative to Au NPs, the velocities of the tip are not high enough to completely exclude the formation of capillary bridges between the tip and particle [37]. The AFM force-curves are conducted at a rate of 2 kHz allowing a contact of both surfaces in the order of the milliseconds [38–39] at ambient temperature (20 °C) and relative humidity around 35 ± 5%.…”

Section: Resultsmentioning

confidence: 99%

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Oras

Vlassov

Berholts

et al. 2018

Beilstein J. Nanotechnol.

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Adhesion forces between functionalized gold colloidal nanoparticles (Au NPs) and scanning probe microscope silicon tips were experimentally investigated by atomic force microscopy (AFM) equipped with PeakForce QNM (Quantitative Nanoscale Mechanics) module. Au NPs were synthesized by a seed-mediated process and then functionalized with thiols containing different functional groups: amino, hydroxy, methoxy, carboxy, methyl, and thiol. Adhesion measurements showed strong differences between NPs and silicon tip depending on the nature of the tail functional group. The dependence of the adhesion on ligand density for different thiols with identical functional tail-group was also demonstrated. The calculated contribution of the van der Waals (vdW) forces between particles was in good agreement with experimentally measured adhesive values. In addition, the adhesion forces were evaluated between flat Au films functionalized with the same molecular components and silicon tips to exclude the effect of particle shape on the adhesion values. Although adhesion values on flat substrates were higher than on their nanoparticle counterparts, the dependance on functional groups remained the same.

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Section: Resultsmentioning

confidence: 99%

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Oras

Vlassov

Berholts

et al. 2018

Beilstein J. Nanotechnol.

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“…In this paper, we focus on F cap as a function of h. As many experiments indicate, capillary forces also contribute significantly to sliding friction and lead to unusual velocity dependence (dynamics) and time dependence (kinetics) [15][16][17][18][19]. It would be interesting to extend the current study to the cases where the tip is displaced laterally so that the liquid bridge is dragged over the substrate surface.…”

Section: Discussionmentioning

confidence: 97%

“…For example, they often prevent micro-or nanoelectromechanical systems from functioning under ambient conditions or lead to damage in their fabrication processes [14]. They play a major role in nanoscopic sliding friction and lead to a nontrivial velocity dependence of friction [15][16][17][18][19]. Many previous experiments also show that when an atomic force microscope (AFM), or more generally any small probe, is used to examine a hydrophilic surface in a humid environment, a major contribution to the tipsurface interaction is from the capillary forces associated with the water meniscus bridging the tip and surface [15,[20][21][22][23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Capillary adhesion at the nanometer scale

Cheng

Robbins

2014

Phys. Rev. E

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Molecular dynamics simulations are used to study the capillary adhesion from a nonvolatile liquid meniscus between a spherical tip and a flat substrate. The atomic structure of the tip, the tip radius, the contact angles of the liquid on the two surfaces, and the volume of the liquid bridge are varied. The capillary force between the tip and substrate is calculated as a function of their separation h. The force agrees with continuum predictions based on macroscopic theory for h down to ∼5 to 10 nm. At smaller h, the force tends to be less attractive than predicted and has strong oscillations. This oscillatory component of the capillary force is completely missed in the macroscopic theory, which only includes contributions from the surface tension around the circumference of the meniscus and the pressure difference over the cross section of the meniscus. The oscillation is found to be due to molecular layering of the liquid confined in the narrow gap between the tip and substrate. This effect is most pronounced for large tip radii and/or smooth surfaces. The other two components considered by the macroscopic theory are also identified. The surface tension term, as well as the meniscus shape, is accurately described by the macroscopic theory for h down to ∼1 nm, but the capillary pressure term is always more positive than the corresponding continuum result. This shift in the capillary pressure reduces the average adhesion by a factor as large as 2 from its continuum value and is found to be due to an anisotropy in the pressure tensor. The component in the plane of the substrate is consistent with the capillary pressure predicted by the macroscopic theory (i.e., the Young-Laplace equation), but the normal pressure that determines the capillary force is always more positive than the continuum counterpart.

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“…We found that a better transfer result can be achieved by peeling off the filter with a quick movement, which is contradictory to the traditional transfer printing processes28. This could be related to the redistribution of water capillary force2930 due to the hydrophilic and porous nature of the PVDF filter, which differs itself from an elastic smooth surface such as PDMS typically used in other transfer printing processes. Afterwards, the gel cake/acrylic structure is soaked in IPA for solvent exchange, and the gel cake can be separated from the acrylic with a little shake.…”

Section: Methodsmentioning

confidence: 82%

Ultrathin (<1 μm) Substrate-Free Flexible Photodetector on Quantum Dot-Nanocellulose Paper

Lin

2017

Sci Rep

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Conventional approaches to flexible optoelectronic devices typically require depositing the active materials on external substrates. This is mostly due to the weak bonding between individual molecules or nanocrystals in the active materials, which prevents sustaining a freestanding thin film. Herein we demonstrate an ultrathin freestanding ZnO quantum dot (QD) active layer with nanocellulose structuring, and its corresponding device fabrication method to achieve substrate-free flexible optoelectronic devices. The ultrathin ZnO QD-nanocellulose composite is obtained by hydrogel transfer printing and solvent-exchange processes to overcome the water capillary force which is detrimental to achieving freestanding thin films. We achieved an active nanocellulose paper with ~550 nm thickness, and >91% transparency in the visible wavelength range. The film retains the photoconductive and photoluminescent properties of ZnO QDs and is applied towards substrate-free Schottky photodetector applications. The device has an overall thickness of ~670 nm, which is the thinnest freestanding optoelectronic device to date, to the best of our knowledge, and functions as a self-powered visible-blind ultraviolet photodetector. This platform can be readily applied to other nano materials as well as other optoelectronic device applications.

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Sliding Velocity Dependence of Adhesion in a Nanometer-Sized Contact

Cited by 37 publications

References 23 publications

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Capillary adhesion at the nanometer scale

Ultrathin (<1 μm) Substrate-Free Flexible Photodetector on Quantum Dot-Nanocellulose Paper

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