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[BestMasters] Topographic Organization of the Pectine Neuropils in Scorpions (An Analysis of Chemosensory Afferents and the Projection Pattern in the Central Nervous System) || Effect of Humidity on the Hydrogen Sensing in Graphene Based Devices
摘要： In this work, we investigate the effect of humidity variations on the sensing performance of Pd-graphene (GR) based devices. Palladium nanoparticles are directly synthetized onto GR sheets by microwave irradiation; the optimal palladium coverage results into a sensitive and fast hydrogen device. The dynamic conductance changes exposed to different hydrogen concentrations from 2.5 to 0.2% are displayed at room temperature, using humidi?ed air as carrier gas at different Relative Humidity (RH) levels. The results show how the sensing curves in low humidity conditions have higher sensitivity with respect to humid environment. On the other hand, dry conditions negatively affect the sensing layer stability over time while humid conditions preserve the material.
关键词： Metal decoration,Hydrogen detection,Graphene
更新于2025-09-19 17:15:36
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Design principles for sensitivity optimization in plasmonic hydrogen sensors
摘要： Palladium nanoparticles have proven to be an exceptionally suitable material for the optical detection of hydrogen gas, due to the dielectric function that changes with the hydrogen concentration. The development of a reliable, low-cost, and widely applicable hydrogen detector requires a simple optical read-out mechanism and an optimization of the lowest detectable hydrogen concentration. So-called ‘perfect absorber’-type structures, consisting of a layer of plasmonic palladium nanoantennas suspended above a metallic mirror layer, are a promising approach to realizing such sensors. The absorption of hydrogen by palladium leads to a shift of the plasmon resonance and thus to a change in the far-?eld re?ectance spectrum. The spectral change can be analyzed in detail using spectroscopic measurements, while the re?ectance change at a speci?c wavelength can be detected with a simple photometric system of a photodiode and a monochromatic light source. Here, we systematically investigate the geometry of cavity-coupled palladium nanostructures as well as the optical system concept, which enables us to formulate a set of design rules for optimizing the hydrogen sensitivity. Employing these principles, we demonstrate the robust detection of hydrogen at concentrations down to 100 ppm. Our results are not limited to hydrogen sensing, but can be applied to any type of plasmonic sensor.
关键词： Hydrogen detection,Palladium,Tailored disorder,Plasmonic sensing,Microspectroscopy,Metasurface,Perfect absorber,Fourier-plane spectroscopy
更新于2025-09-16 10:30:52
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Probing the Electronic Properties of Monolayer MoS <sub/>2</sub> via Interaction with Molecular Hydrogen
摘要： This work presents a detailed experimental investigation of the interaction between molecular hydrogen (H2) and monolayer MoS2 field effect transistors (MoS2 FET), aiming for sensing application. The MoS2 FET exhibits a response to H2 that covers a broad range of concentration (0.1–90%) at a relatively low operating temperature range (300–473 K). Most important, H2 sensors based on MoS2 FETs show desirable properties such as full reversibility and absence of catalytic metal dopants (Pt or Pd). The experimental results indicate that the conductivity of MoS2 monotonically increases as a function of the H2 concentration due to a reversible charge transferring process. It is proposed that such process involves dissociative H2 adsorption driven by interaction with sulfur vacancies in the MoS2 surface (VS). This description is in agreement with related density functional theory studies about H2 adsorption on MoS2. Finally, measurements on partially defect-passivated MoS2 FETs using atomic layer deposited aluminum oxide consist of an experimental indication that the VS plays an important role in the H2 interaction with the MoS2. These findings provide insights for future applications in catalytic process between monolayer MoS2 and H2 and also introduce MoS2 FETs as promising H2 sensors.
关键词： hydrogen gas sensor,gas interaction,hydrogen detection,monolayer MoS2,field effect transistors
更新于2025-09-10 09:29:36
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[IEEE 2018 XV International Scientific Conference on Optoelectronic and Electronic Sensors (COE) - Warsaw, Poland (2018.6.17-2018.6.20)] 2018 XV International Scientific Conference on Optoelectronic and Electronic Sensors (COE) - Array of Gas Sensors Based on TiO2 Upon Temperature Modulation
摘要： The aim of this work is to demonstrate that thermal modulation improves the selectivity of TiO2 – based resistive-type gas sensors. The sensors operate upon sinusoidal temperature profile over a temperature range of 240 – 300°C. Sensor array is composed of nanocrystalline TiO2:Cr (0.1 – 10 at.% Cr). The switching from n-type to p-type conductivity occurs at about 1 at. % Cr. Electrical resistance responses to reducing and oxidizing gases such as: NO, NO2, H2, CH4, C3H8 (0 – 3000 ppm) are dynamically recorded and compared in order to assess cross-sensitivity as well as humidity interference. The results of the Principle Component Analysis, PCA demonstrate that reliable detection and classification of H2, and NOx have been achieved.
关键词： sensors array,hydrogen detection,humidity,temperature modulation,TiO2:Cr nanomaterials
更新于2025-09-10 09:29:36
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Flexible, multifunctional nanoribbon arrays of palladium nanoparticles for transparent conduction and hydrogen detection
摘要： A novel combination of nanostructuring techniques is undertaken to obtain a multifunctional material system consisting of planar arrays of nanoribbons of Pd nanoparticles (NPs) on polyethylene terephthalate (PET) substrates. The first stage was to prepare a laser-induced periodic surface structure (LIPSS) on the PET substrate, which electron microscopy revealed to be a large area, high coherence nanoripple pattern with spacing of (204 ± 1) nm and amplitude of (46 ± 9) nm. The second stage comprised NP (diameter 5 nm) deposition by orientating the nanostructured substrate to a Pd NP beam from a sputter gas phase aggregation source such that the substrate was partially shadowed by the ripple pattern (the incident angle with respect to the normal of the PET substrate was varied between 60 and 75o). This resulted in the formation of an array of NP ribbons (thickness ? 20 nm) on the ripple ridges, the mean ribbon width depending on the deposition incidence angle, thus confirming the shadowing effect. These planar arrays were studied as candidates for both flexible, transparent conductors and hydrogen sensors. Analysis of optical transmittance indicates that a mean inter-ribbon gap of above 100 nm is required in order to improve the average transmittance beyond 80 %. Four-probe electrical resistance measurements show these nanoribbon arrays to be electrically anisotropic structures whose sheet resistance is understood to be governed by the contact resistance between NPs. An additional functionality is proven for the fabricated substrates: reversible detection of hydrogen at a partial pressure above ? 60 ppm, with good electrical sensitivity in the dilute (?-hydride) regime.
关键词： palladium,Laser Induced Periodic Surface Structures,oblique deposition,nanoparticles,transparent conductors,hydrogen detection
更新于2025-09-10 09:29:36