25 research outputs found
Neutral particle Mass Spectrometry with Nanomechanical Systems
Current approaches to Mass Spectrometry (MS) require ionization of the
analytes of interest. For high-mass species, the resulting charge state
distribution can be complex and difficult to interpret correctly. In this
article, using a setup comprising both conventional time-of-flight MS (TOF-MS)
and Nano-Electro-Mechanical-Systems-based MS (NEMS-MS) in situ, we show
directly that NEMS-MS analysis is insensitive to charge state: the spectrum
consists of a single peak whatever the species charge state, making it
significantly clearer than existing MS analysis. In subsequent tests, all
charged particles are electrostatically removed from the beam, and unlike
TOF-MS, NEMS-MS can still measure masses. This demonstrates the possibility to
measure mass spectra for neutral particles. Thus, it is possible to envisage
MS-based studies of analytes that are incompatible with current ionization
techniques and the way is now open for the development of cutting edge system
architectures with unique analytical capability
High Frequency top-down Junction-less Silicon Nanowire Resonators
We report here the first realization of top-down silicon nanowires (SiNW)
transduced by both junction-less field effect transistor (FET) and the
piezoresistive (PZR) effect. The suspended SiNWs are among the smallest
top-down SiNWs reported to date, featuring widths down to ~20nm. This has been
achieved thanks to a 200mm-wafer-scale, VLSI process fully amenable to
monolithic CMOS co-integration. Thanks to the very small dimensions, the
conductance of the silicon nanowire can be controlled by a nearby electrostatic
gate. Both the junction-less FET and the previously demonstrated PZR
transduction have been performed with the same SiNW. These self-transducing
schemes have shown similar signal-to-background ratios, and the PZR
transduction has exhibited a relatively higher output signal. Allan deviation
AD of the same SiNW has been measured with both schemes, and we obtain AD~20ppm
for the FET detection and AD~3ppm for the PZR detection at room temperature and
low pressure. Orders of magnitude improvements are expected from tighter
electrostatic control via changes in geometry and doping level, as well as from
CMOS integration. The compact, simple topology of these elementary SiNW
resonators opens up new paths towards ultra-dense arrays for gas and mass
sensing, time keeping or logic switching systems in SiNW-CMOS platform
Strain Measurements During Structural Conservation Treatment and the Long-term Monitoring of a 17th-century Dutch Panel Painting
No abstract available
Strain Measurements During Structural Conservation Treatment and the Long-term Monitoring of a 17th-century Dutch Panel Painting
No abstract available
Image Correlation to Evaluate the Influence of Hygrothermal Loading on Wood
International audienceMany wooden objects from cultural heritage consist in wooden panels, painted on one face. Some of these panels show permanent cupping, micro-cracks of the painted layer, and cracks of the painted support itself. Different physical and mechanical phenomena are at the origin of these damages: wood is a hygroscopic material (its dimensions vary with humidity), it is highly anisotropic, the paint layer on one face has properties of permeability different from those of raw wood of the back face, and a rigid frame possibly restrained the deformation of the panel. Experimentations on our mock-up panels combined with numerical simulations of these panels in real situations of hygrothermal fluctuations will allow us to test specific situations and eventually to make suggestions to conservators and restorers and guide them in their interventions. Hygrothermal treatments are often used to improve wood durability thanks a reduction of its hygroscopicity. They have been considered as means to reproduce the physical properties of ancient wood. We intend to model the mechanisms involved in mechanical and chemical effects of wooden painted panels exposed to climatic variations. To develop such conservation tool, we need to work on mock-up, which replicate panel painting. So we will investigate the process of hygroscopic ageing and compression set generation of the back of painted panels to explain their permanent cupping and replicate their ageing state. For this purpose, digital image correlation is used to evaluate the strain field of the section of a wood piece submitted to variations of relative humidity
Étude expérimentale et numérique du comportement hygromécanique d’un panneau de bois. Application à la conservation des tableaux peints sur bois du patrimoine
No abstract available
Étude expérimentale et numérique du comportement hygromécanique d’un panneau de bois. Application à la conservation des tableaux peints sur bois du patrimoine
No abstract available
Characterisation and modelling of nonlinear resonance behaviour on very-high-frequency silicon nanoelectromechanical resonators
This paper reports a novel method to build a model for nonlinear resonance behaviour of very-high-frequency (VHF) silicon nanoelectromechanical (NEM) resonators, measured via 1-ω mixing resonance measurements. Systematic fitting results for the experimental data of a 1.5-μm-long beams have been achieved with explicit explanation of the amount of intrinsic mechanical nonlinearity and nonlinear voltage-tuning effect. Asymmetric line shape and onset of hysteresis on nonliner resonance behavour have been well demonstrated with less fitting errors. The development of a modelling method of nanoscale resonator devices which includes nonlinear response is beneficial for seamless technology transfer from individual devices to integrated systems in the future