Search results for "Gas sensor"
showing 10 items of 43 documents
Chromatographic Air Analyzer Microsystem for the Selective and Sensitive Detection of Explosive-related Compounds
2014
Abstract The detection of explosives and explosive-related compounds is of major importance for the monitoring of explosive- contaminated sites. Current methods need to become cheaper and portable while maintaining a high sensitivity and selectivity level. In that sense, a silicon micro-analytical platform consisting of a three-dimensional micro-preconcentrator based on a hydrophobic zeolite, coupled to a silicon spiral micro-column was built. A chemical gas sensor acted as a miniaturized gas detector. This system allowed selective detection of orthonitrotoluene (ONT), an explosive-related compound at the sub-ppm level in the presence of toluene and moisture.
Supercontinuum generation in chalcogenides : application to gas spectroscopy in atmospheric band III
2023
This thesis work aims to contribute to the development of new fiber sources emitting over a wide range of wavelengths in the IR, in particular to detect greenhouse gases in the mid-infrared range. Our spectroscopy results with nitrous oxide N2O and methane CH4 are obtained in band III. To achieve this, the generation of supercontinuum (SC) covering band III was made possible by using chalcogenide optical fibers, purified and free of highly toxic elements according to REACH regulations, in particular arsenic and antimony. The fibrable vitreous composition belonging to the Ge-Se-Te ternary system fits perfectly into the context of sustainable development, it is the one that has been identifie…
Nanostructured Based Electrochemical Sensors.
2019
In this work, we present some results concerning the electrochemical behavior of nanostructured-based electrochemical sensors. In particular, the attention has been focused on Pd and Cu nanowires for detection of hydrogen peroxide and NiO thin film or Ni@NiO core–shell nanowires for detection of mercury ions. Ordered array of Pd and Cu nanowires was obtained through displacement deposition reaction in a commercial polycarbonate membrane acting as a template. The method leads to stable nanostructured electrodes of Pd and Cu with high surface area. For the detection of mercury ions, we have fabricated a Ni/NiO electrochemical sensor, obtained by mild thermal oxidation of Ni-foil. Some results…
Les matériaux pour capteurs chimiques
2002
National audience; A chemical sensor is composed of one part supplying chemical reco gnition coupled to one transducingsystem. At the recognition origin, interaction with the target chemical species is oftwo types, either electronicexchange, or ionic exchange. Two large classes of materials that can supply recognition proceed: metals andsemiconductors giving rise to electronic exchange and ionic conducting materials giving rise to ionic exchan-ge. This paper is structured in tw o large parts, emphasizing on materi als inducing specific interactions:semiconductor materials (metallic oxides and molecular semiconductors) and ionic conductor materials.In each part will be presented nature of ma…
Changes in surface stress, morphology and chemical composition of silica and silicon nitride surfaces during the etching by gaseous HF acid
2007
International audience; HF acid attack of SiO2 and Si3N4 substrates is analyzed to improve the sensitivity of a sensor based on inicrocantilever. Ex situ analysis of the etching using XPS, SIMS and AFM show significant changes in the anisotropy and the rate of the etching of the oxides on SiO2 and Si3N4 surface. Those differences influence the kinetic evolution of the plastic bending deflection of the cantilever coated with SiO2 and Si3N4 layer, respectively. The linear dependence between the HF concentration and the Si3N4 cantilever bending corresponds to a deep attack of the layer whereas the nonlinear behavior observed for SiO2 layer can be explained by a combination of deep and lateral …
Supercontinuum generation in chalcogenide: application to gas spectroscopy in atmospheric band III
2023
This thesis work aims to contribute to the development of new fiber sources emitting over a wide range of wavelengths in the IR, in particular to detect greenhouse gases in the mid-infrared range. Our spectroscopy results with nitrous oxide N2O and methane CH4 are obtained in band III. To achieve this, the generation of supercontinuum (SC) covering band III was made possible by using chalcogenide optical fibers, purified and free of highly toxic elements according to REACH regulations, in particular arsenic and antimony. The fibrable vitreous composition belonging to the Ge-Se-Te ternary system fits perfectly into the context of sustainable development, it is the one that has been identifie…
An electrochemically synthesized nanoporous copper microsensor for highly sensitive and selective determination of glyphosate
2020
Application of Electronic Nose for Evaluation of Wastewater Treatment Process Effects at Full-Scale WWTP
2019
This paper presents the results of studies aiming at the assessment and classification of wastewater using an electronic nose. During the experiment, an attempt was made to classify the medium based on an analysis of signals from a gas sensor array, the intensity of which depended on the levels of volatile compounds in the headspace gas mixture above the wastewater table. The research involved samples collected from the mechanical and biological treatment devices of a full-scale wastewater treatment plant (WWTP), as well as wastewater analysis. The measurements were carried out with a metal-oxide-semiconductor (MOS) gas sensor array, when coupled with a computing unit (e.g., a computer with…
Microwave gas sensor based on graphene aerogel for breath analysis
2022
Exhaled breath can be used for early detection and diagnosis of diseases, monitoring metabolic activity, and precision medicine. In this work, we design and simulate a microwave sensor in which thin graphene aerogels are integrated into rectangular microwave waveguides. Graphene aerogels are ideal sensing platforms for gases and volatile compounds as they combine extremely high surface-to-volume ratio and good electrical conductivity at RF and microwave frequencies. The latter is modified by exposure to different gases, and -when integrated into a waveguide- these changes result in significant shifts in transmission and reflection scattering parameters. We model the aerogel as a graphene gr…
Alkylthio-tetrasubstituted μ-Nitrido Diiron Phthalocyanines: Spectroelectrochemistry, Electrical Properties, and Heterojunctions for Ammonia Sensing.
2020
Alkylthio-tetrasubstituted μ-nitrido diiron phthalocyanine complexes are synthesized with n-butyl, iso-butyl, tert-butyl, and n-hexadecyl alkyl moieties. For the first time, a spectroelectrochemical investigation of μ-nitrido diiron phthalocyanines is achieved at all the redox steps. The complexes are stable in all their redox states, unlike their unsubstituted analogues. The interest of the present complexes is to prepare sensing devices by a solution processing method. Films are characterized by electronic absorption and Raman spectroscopies. Electrical measurements on resistors show the highly resistive behavior of these complexes, whatever the chain length. However, when combined with t…