scholarly journals Ternary Oxidized Carbon Nanohorns/TiO2/PVP Nanohybrid as Sensitive Layer for Chemoresistive Humidity Sensor

2021 ◽  
Vol 5 (1) ◽  
pp. 12
Author(s):  
Bogdan-Catalin Serban ◽  
Octavian Buiu ◽  
Marius Bumbac ◽  
Roxana Marinescu ◽  
Niculae Dumbravescu ◽  
...  
Keyword(s):  
Thin Film ◽  
Relative Humidity ◽  
Nitrogen Atmosphere ◽  
Sensing Element ◽  
Sensitive Layer ◽  
Sio2 Substrate ◽  
Casting Technique ◽  
Carbon Nanohorns ◽  
Comb Structure ◽  
Oxidized Carbon

The relative humidity (RH) sensing response of a chemoresistive sensor using a novel ternary hybrid nanocomposite film as a sensing element is presented. The sensitive layer was obtained by employing the drop-casting technique for depositing a thin film of nanocomposite between the electrodes of an interdigitated (IDT) structure. The sensing support structure consists of an IDT dual-comb structure fabricated on a oSi-SiO2 substrate. The IDT comprises chromium, as an adhesion layer (10 nm thickness), and a gold layer (100 nm thickness). The sensing capability of a novel thin film based on a ternary hybrid made of oxidated carbon nanohorns–titanium dioxide–polyvinylpyrrolidone (CNHox/TiO2/PVP) nanocomposite was investigated by applying a direct current with known intensity between the two electrodes of the sensing structure, and measuring the resulting voltage difference, while varying the RH from 0% to 100% in a humid nitrogen atmosphere. The ternary hybrid-based thin film’s resistance increased when the sensors were exposed to relative humidity ranging from 0 to 100%. It was found that the performance of the new chemoresistive sensor is consistent with that of the capacitive commercial sensor used as a benchmark. Raman spectroscopy was used to provide information on the composition of the sensing layer and on potential interactions between constituents. Several sensing mechanisms were considered and discussed, based on the interaction of water molecules with each component of the ternary nanohybrid. The sensing results obtained lead to the conclusion that the synergic effect of the p-type semiconductor behavior of the CNHox and the PVP swelling process plays a pivotal role in the overall resistance decrease of the sensitive film.

scholarly journals Quaternary Oxidized Carbon Nanohorns—Based Nanohybrid as Sensing Coating for Room Temperature Resistive Humidity Monitoring

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 530
Author(s):  
Bogdan-Catalin Serban ◽  
Cornel Cobianu ◽  
Octavian Buiu ◽  
Marius Bumbac ◽  
Niculae Dumbravescu ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Tin Dioxide ◽  
Temperature Response ◽  
Relative Sensitivity ◽  
Hybrid Nanocomposites ◽  
Carbon Nanohorns ◽  
Recovery Times ◽  
Oxidized Carbon ◽  
Role Based

We report the relative humidity (RH) sensing response of a resistive sensor, employing sensing layers, based on a quaternary organic–inorganic hybrid nanocomposite comprising oxidized carbon nanohorns (CNHox), graphene oxide (GO), tin dioxide, and polyvinylpyrrolidone (PVP), at 1/1/1/1 and 0.75/0.75/1/1/1 mass ratios. The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensing film was deposited via the drop-casting method on the sensing structure. The morphology and the composition of the sensing layers were investigated through Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and RAMAN spectroscopy. The organic–inorganic quaternary hybrid-based thin film’s resistance increased when the sensors were exposed to relative humidity ranging from 0 to 100%. The manufactured devices show a room temperature response comparable to that of a commercial capacitive humidity sensor and characterized by excellent linearity, rapid response and recovery times, and good sensitivity. While the sensor with CNHox/GO/SnO2/PVP at 0.75/0.75/1/1 as the sensing layer has the best performance in terms of linearity and recovery time, the structures employing the CNHox/GO/SnO2/PVP at 1/1/1/1 (mass ratio) have a better performance in terms of relative sensitivity. We explained each constituent of the quaternary hybrid nanocomposites’ sensing role based on their chemical and physical properties, and mutual interactions. Different alternative mechanisms were taken into consideration and discussed. Based on the sensing results, we presume that the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of PVP, dominates and leads to the overall increasing resistance of the sensing layer. The hard–soft acid–base (HSAB) principle also supports this mechanism.

scholarly journals The Influence of Climate Conditions and On-Skin Positioning on InGaZnO Thin-Film Transistor Performance

2022 ◽  
Vol 2 ◽  
Author(s):  
Federica Catania ◽  
Hugo De Souza Oliveira ◽  
Martina A. Costa Angeli ◽  
Manuela Ciocca ◽  
Salvador Pané ◽  
...  
Keyword(s):  
Thin Film ◽  
Relative Humidity ◽  
Thin Film Transistor ◽  
Industrial Applications ◽  
Indium Gallium Zinc Oxide ◽  
Sensing Element ◽  
Climate Conditions ◽  
Indium Gallium ◽  
Effects Of Temperature ◽  
Igzo Tft

Thin-film transistors (TFTs) based on amorphous indium-gallium-zinc-oxide (a-IGZO) have proved promising features for flexible and lightweight electronics. To achieve technological maturity for commercial and industrial applications, their stability under extreme environmental conditions is highly required. The combined effects of temperature (T) from −30.0°C to 50.0°C and relative humidity (RH) stress from 0 to 95% on a-IGZO TFT is presented. The TFT performances and the parameters variation were analysed in two different experiments. First, the TFT response was extracted while undergoing the most extreme climate conditions on Earth, ranging from the African Desert (50.0°C, 22%) to Antarctic (−30.0°C, 0%). Afterwards, the device functionality was demonstrated in three parts of the human body (forehand, arm and foot) at low (35%), medium (60%) and high (95%) relative humidity for on-skin and wearable applications. The sensitivity to T/RH variations suggests the suitability of these TFTs as sensing element for epidermal electronics and artificial skin.

scholarly journals Quaternary Holey Carbon Nanohorns/SnO2/ZnO/PVP Nano-Hybrid as Sensing Element for Resistive-Type Humidity Sensor

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1307
Author(s):  
Bogdan-Catalin Serban ◽  
Cornel Cobianu ◽  
Octavian Buiu ◽  
Marius Bumbac ◽  
Niculae Dumbravescu ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Chemical Properties ◽  
Dielectric Substrate ◽  
Nitrogen Atmosphere ◽  
Hybrid Nanocomposites ◽  
Hybrid Nanocomposite ◽  
Sensing Element ◽  
X Ray ◽  
Carbon Nanohorns ◽  
The Impact

In this study, a resistive humidity sensor for moisture detection at room temperature is presented. The thin film proposed as a critical sensing element is based on a quaternary hybrid nanocomposite CNHox//SnO2/ZnO/PVP (oxidated carbon nanohorns–tin oxide–zinc oxide–polyvinylpyrrolidone) at the w/w/w/w ratios of 1.5/1/1/1 and 3/1/1/1. The sensing structure consists of a Si/SiO2 dielectric substrate and interdigitated transducers (IDT) electrodes, while the sensing film layer is deposited through the drop-casting method. Morphology and composition of the sensing layers were investigated through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction, and Raman spectroscopy. Each quaternary hybrid nanocomposite-based thin film’s relative humidity (RH) sensing capability was analyzed by applying a direct current with known intensity between two electrodes and measuring the voltage difference when varying the RH from 0% to 100% in a humid nitrogen atmosphere. While the sensor with CNHox/SnO2/ZnO/PVP at 1.5/1/1/1 as the sensing layer has the better performance in terms of sensitivity, the structure employing CNHox//SnO2/ ZnO/PVP at 3/1/1/1 (mass ratio) as the sensing layer has a better performance in terms of linearity. The contribution of each component of the quaternary hybrid nanocomposites to the sensing performance is discussed in relation to their physical and chemical properties. Several alternative sensing mechanisms were taken into consideration and discussed. Based on the measured sensing results, we presume that the impact of the p-type semiconductor behavior of CNHox, in conjunction with the swelling of the hydrophilic polymer, is dominant and leads to the overall increasing resistance of the sensing film.

scholarly journals Electrical Percolation Threshold and Size Effects in Polyvinylpyrrolidone-Oxidized Single-Wall Carbon Nanohorn Nanocomposite: The Impact for Relative Humidity Resistive Sensors Design

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1435
Author(s):  
Bogdan-Catalin Serban ◽  
Cornel Cobianu ◽  
Niculae Dumbravescu ◽  
Octavian Buiu ◽  
Marius Bumbac ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Percolation Threshold ◽  
Threshold Value ◽  
Electrode Spacing ◽  
Humidity Sensors ◽  
Carbon Nanohorns ◽  
Electrical Percolation ◽  
Oxidized Carbon ◽  
Electrical Percolation Threshold ◽  
Percolation Thresholds

This paper reports, for the first time, on the electrical percolation threshold in oxidized carbon nanohorns (CNHox)–polyvinylpyrrolidone (PVP) films. We demonstrate—starting from the design and synthesis of the layers—how these films can be used as sensing layers for resistive relative humidity sensors. The morphology and the composition of the sensing layers are investigated through Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and RAMAN spectroscopy. For establishing the electrical percolation thresholds of CNHox in PVP, these nanocomposite thin films were deposited on interdigitated transducer (IDT) dual-comb structures. The IDTs were processed both on a rigid Si/SiO2 substrate with a spacing of 10 µm between metal digits, and a flexible substrate (polyimide) with a spacing of 100 µm. The percolation thresholds of CNHox in the PVP matrix were equal to (0.05–0.1) wt% and 3.5 wt% when performed on 10 µm-IDT and 100 µm-IDT, respectively. The latter value agreed well with the percolation threshold value of about 4 wt% predicted by the aspect ratio of CNHox. In contrast, the former value was more than an order of magnitude lower than expected. We explained the percolation threshold value of (0.05–0.1) wt% by the increased probability of forming continuous conductive paths at much lower CNHox concentrations when the gap between electrodes is below a specific limit. The change in the nanocomposite’s longitudinal Young modulus, as a function of the concentration of oxidized carbon nanohorns in the polymer matrix, is also evaluated. Based on these results, we identified a new parameter (i.e., the inter-electrode spacing) affecting the electrical percolation threshold in micro-nano electronic devices. The electrical percolation threshold’s critical role in the resistive relative-humidity sensors’ design and functioning is clearly emphasized.

scholarly journals Formation of a Complex Topologies of SAW-Based Inertial Sensors by Laser Thin Film Local Evaporation

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Alexander Kukaev ◽  
Dmitry Lukyanov ◽  
Denis Mikhailenko ◽  
Daniil Safronov ◽  
Sergey Shevchenko ◽  
...  
Keyword(s):  
Thin Film ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Acoustic Waves ◽  
Inertial Sensors ◽  
Surface Acoustic Waves ◽  
Sensing Element ◽  
Small Series ◽  
Evaporation Technique ◽  
Photolithography Process

Originally, sensors based on surface acoustic waves are fabricated using photolithography, which becomes extremely expensive when a small series or even single elements are needed for the research. A laser thin film local evaporation technique is proposed to substitute the photolithography process in the production of surface acoustic wave based inertial sensors prototypes. To estimate its potential a prototype of a surface acoustic wave gyroscope sensing element was fabricated and tested. Its was shown that the frequency mismatch is no more than 1%, but dispersion of the wave on small inertial masses leads to a spurious parasitic signal on receiving electrodes. Possible ways of its neglecting is discussed.

A Low-Range Drift-Free Bio-compatible Pressure Sensor Based on P(VDF-TrFE) Piezoelectric Thin Film

2009 ◽  
Vol 1222 ◽  
Author(s):  
Xiaoyang Li ◽  
Timothy Reissman ◽  
Fan Yu ◽  
Edwin C. Kan
Keyword(s):  
Thin Film ◽  
Blood Pressure ◽  
Pressure Sensor ◽  
Equivalent Circuit Model ◽  
Swelling Pressure ◽  
Pressure Monitoring ◽  
Sensing Element ◽  
Piezoelectric Resonance ◽  
Piezoelectric Thin Film

AbstractA low-range pressure sensor (0-100kPa) based on the P(VDF-TrFE) piezoelectric thin film is proposed, where the long-term drift is eliminated by operating near the piezoelectric resonance. The pressure sensor is designed for blood pressure and tissue swelling pressure monitoring. The poled 50μm±1μm P(VDF-TrFE) copolymer film is used as the sensing element, with all fabrication and assembly materials biocompatible. A modified Butterworth-Van Dyke (BVD) [1] equivalent circuit model is used to characterize the sensor behavior. The pressure sensor exhibits negligible drift in weeks of operation. The device shows a sensitivity of 0.038MHz/kPa resonance frequency shift under stress, which leads to a maximum readout change of 1.1%/kPa in the present setup.

Thin-Film X-Ray Spectroscopy

1961 ◽  
Vol 5 ◽  
pp. 500-511 ◽  
Author(s):  
J.J. Finnegan
Keyword(s):  
Thin Film ◽  
Matrix Effect ◽  
Film Casting ◽  
X Ray ◽  
Nickel Films ◽  
Casting Technique ◽  
Glass Substrates ◽  
Iron Nickel

AbstractQuantitative de terminations of thickness and composition are presented for 100- to 10,000-A iron-nickel films. Calibration of X-ray intensities with interferometric and calorimetric values give linear plots for films deposited on Mylar or glass substrates. Application of a film-casting technique shows promise of alleviating two of the problems encountered in X-ray spectroscopy, i.e., matrix-effect-caused deviations from proportionality and the lack of standards for calibration of many types of material.

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