Publications by authors named "Benoit Viallet"
Nanoparticle assemblies with thiol-terminated alkyl chains are studied by conducting atomic force microscopy (c-AFM) regarding their use as strain gauges for touch-sensitive panels. Current-force spectroscopy is used as a characterization tool complementary to the macroscopic setup since it allows a bias to be applied to a limited number of junctions, overcoming the Coulomb blockade energy and focusing on the contact electromechanics and the transport mechanism across the ligand. First, transition voltage spectroscopy is applied with varying force to target the underlying tunneling mechanism by observing whether the transition between the ohmic and exponential current-voltage behavior is force-dependent.
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- A study investigates how nanoparticle-based strain gauges behave under different strain conditions using techniques like small angle X-ray scattering (SAXS) and grazing incidence SAXS.
- The strain gauges were made from gold nanoparticles on flexible materials, and the research found that stretching caused certain microstructural and electrical resistance changes in the nanoparticle wires.
- Results indicate that while longitudinal stretching occurs, there’s a decrease in width and a loss of directional sensitivity in the strain gauges due to transversal current flow through the nanoparticle wires.
Article Synopsis
- The study focuses on understanding how electrons move in strain gauges made from gold colloidal nanoparticles (NPs) that are coated with different organic ligands.
- The research shows that the electron transport happens through tunneling, which is affected by the type of ligands used; specifically, phosphine and thiol ligands resulted in higher gauge sensitivity.
- Temperature resistance tests revealed two different behavior regimes (strong and weak coupling), with the weak-coupling regime gauges demonstrating higher tunneling decay constants and significant Coulomb charging energy affecting electron transport.
High-sensitivity strain gauges based on single wires of close-packed 14 nm colloidal gold nanoparticles are obtained by a novel variant of convective self-assembly (CSA). This CSA mode named stop-and-go CSA enables the fabrication of nanoparticle wires only a few micrometers wide, separated by distances that can be easily tuned over tens to hundreds of micrometers. Nanoparticle wires are obtained in a single step by direct deposition of nanoparticles from suspensions onto flexible polyethylene terephthalate films, without any lithographic prepatterning.
View Article and Find Full Text PDFOrdered arrays of centimeter-long nanoparticle wires are fabricated by convective self-assembly from aqueous suspensions of 18 nm gold colloids, on flat SiO(2)/Si substrates without any prepatterning. The orientation of the wires can be switched from parallel to perpendicular to the substrate-liquid-air contact line by controlling the substrate temperature. While the wires parallel to the meniscus are obtained by a stick-slip process, a mechanism based on critical density-triggered particle pinning is proposed to explain the formation of wires perpendicular to the meniscus.
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