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Comparison of response/recovery time of MOS sensors in different hydrogen concentrations.
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Background
Hydrogen sensors are micro/nano-structure that are used to locate hydrogen leaks. They are considered to have fast response/recovery time and long lifetime as compared to conventional gas sensors. In this paper, fabrication of sensitive capacitive-type hydrogen gas sensor based on Ni thin film has been investigated. The C-V curves of the...
Contexts in source publication
Context 1
... behavior is related to the decrease of the metal work functions and a larger shift in the V FB . Comparison of response/recovery time of MOS sensor to different hydrogen concentration is shown in Table 1. As can be seen in Table 1 for the MOS sensor with 20 nm oxide thickness by increase in the hydro- gen concentration from 1% to 4%, the response times are decreased from 28 s to 21 s. ...
Context 2
... of response/recovery time of MOS sensor to different hydrogen concentration is shown in Table 1. As can be seen in Table 1 for the MOS sensor with 20 nm oxide thickness by increase in the hydro- gen concentration from 1% to 4%, the response times are decreased from 28 s to 21 s. As a result from Fig. (10) and Fig. (11), the number of hydrogen atoms in the Ni/SiO 2 in- terface increases with the decrease in the oxide film thick- ness. ...
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Citations
... 108 Very high power consumption (0.5−3.0 W) was used for obtaining high temperatures while taking continuously longer reaction times (>8 s). 109 On increasing the temperature for driving the oxygen atoms to leave the grain boundary, more hydrogen atoms get diffused in the lattice vacancies, which builds altered electrical conduction pathways and slows down the electron conduction. 110 3.2.4. ...
The implementation of hydrogen, as a renewable and clean energy source, has the potential to replace fossil fuels and
to decarbonize hard-to-abate sectors, enabling sustainable development with a lower environmental footprint. At concentrations
higher than 4 vol %, hydrogen is, however, highly flammable and real-time monitoring and detection are required to ensure safe
operation during production, storage, transportation, and utilization of it. Hydrogen sensors shall, therefore, be both efficient and
sensitive to operate across a wide range of concentrations and mixtures with other gases. Current commercial hydrogen sensors are
primarily dependent on electrochemical, heat-conductance, or calorimetric technologies, being intrinsically developed from noble
and expensive metals or complex setups. Portable hydrogen sensing technologies for personal protective equipment in remote and
confined areas shall, however, require them to be selective and specific, light weight, and mobile, as well as self-regenerating and
stable for the long-term. An emerging type of hydrogen sensor involves biosensing through biological pathways whereby
hydrogenase is extracted from microbial communities and used for carrying out the reversible hydrogen oxidation reaction, allowing
sensitivity down to 0.4 ppb in complex environments. Microbial communities innately use hydrogen for metabolic activities related
to growth and energy synthesis. This review highlights the recent developments in hydrogen biosensing while presenting viable
options for on-site and fast hydrogen detection, allowing timely action for mitigating risks related to hydrogen leakages and
inflammation. Beyond discussing the mechanisms and materials used to generate hydrogen biosensors, a critical comparison with
conventional hydrogen and other gaseous sensors is presented, highlighting the opportunities and remaining challenges in this field.
... 7 Research on H 2 sensors has been carried out in platinum (Pt), nickel (Ni), titanium dioxide (TiO 2 ), zinc oxide (ZnO), palladium-gold alloy (PdAu), tin(IV) oxide (SnO 2 ) and Pt 80 Au 14 Ti 6 . [8][9][10][11][12][13][14] Research of H sensors using Pt 80 Au 14 Ti 6 based on CPD properties shows the signal (-297 ± 9) mV for 15,000 ppm H 2 . Pt 80 Au 14 Ti 6 also has cross-sensitivity to the 50 ppm NH 3 and five ppm NO 2 with its signal, i.e., (100 ± 20) mV and (50 ± 10) mV. ...
Chemical reactions simulation in detecting hydrogen gas (H2) on Pt80Au14Ti6 sensor surface based on work function change (Δɸ) has been conducted. The simulation result is compared with laboratory results of detecting H2 gas. Three chemical reactions contained three coverages, H coverage (θH), O coverage (θO), and H2O coverage (θH2O). The simulation was run using MATLAB. This research can find the reaction parameter values such as the Arrhenius coefficient of H2O forming reaction on Pt (υf3Pt), H2O forming reaction on Au (υf3Au), i.e., H2O dissociation on Au (υf3Au ), O2 desorption on Ti (υd2Ti), H2O forming reaction on Ti (υf3Ti), and H2O dissociation on Ti (υf3Ti), i.e., 7.5×1014 s–1, 9.85×1015 s–1, 3.25×1015 s–1, 7.11×1015 s–1, 3.425×1015 s–1 and 2.725×1015 s–1, respectively. The simulation results also have the same trend as the laboratory results. However, the contact potential difference (CPD) simulation result, i.e., –240 mV, is not the same as the laboratory result, (–297± 9) mV. In addition, this simulation also obtained approximation coverage for atoms/molecules on PT80Au14Ti6 surface, i.e., θH = 0.665154 Mono Layer (ML); θO = 1.5621× 10–6 ML; and θH2O = 5.41676 ×10–5 ML.
... Presence detection and concentration measurement of H 2 , possess over one century of history [6,7]. For the development of H 2 sensors, a large number of techniques have been reported, e.g., thin metal film [8][9][10][11], nano-structure [12][13][14][15][16], optical [17,18], acoustic wave [19,20], metal oxides [21][22][23], and semiconductor [24,25]. Among these types, metal oxides like SnO 2 and ZnO, are typically used as sensitive constituents, which can cause redox reactions with H 2 , further resulting in related sensitivity by tuning physical and/or chemical properties. ...
Palladium-based H2 sensors have attracted increased attention due to the high selectivity for H2, yet evident limitations like hydrogen embrittlement and slow response rates, have impeded the further development. Aiming to address these issues, adding other metals to form Pd-based alloys and optimize coincided surface structure, are widely considered as effective approaches. Here in this work, Pd/Ti alloy films with proper elemental ratios were prepared by using a magnetron co-sputtering technique, and the coincided sensing features have been further regulated by in situ nanostructuring. For the Pd/Ti film with an atomic ratio of 74.1/25.9, the H2 response values characterizations revealed that the limit of detection (LoD) could be 50 ppm at room temperature, combined with a response time of 61.3 s at 2 vt.% H2 concentration. Based on the first-principles calculations, the effects from hydrogen diffusion process of Pd and Pd/Ti alloys have been evaluated to be ignorable, however, the specific nanostructures constructed on the surface then become the main reason for the boosted response performance. More importantly, the approach of forming proper in situ nanoparticles has been identified as a significant guidance, for extensive and rapid response of H2 detection of Pd-based sensors used upon low power consumption.
... Metal oxide semiconductor (MOS)-, surface acoustic wave (SAW)-, and field effect transistor (FET)-based hydrogen gas sensors have been widely developed. [3][4][5] Among the MOS-based gas sensors, ZnO with various morphologies is being used as active layer due to its low cost, non toxic, physical and chemical properties. [6][7][8][9] ZnO has unique characteristics, including high mobility, thermal stability, a photoelectric response with significant exciton binding energy, and a wide band gap, all of which are ideal for hydrogen gas sensors. ...
Hydrogen is considered to be the subsequent energy source derived from hydrogen evolution reactions. To ensure safety when using this harmful gas, hydrogen gas sensors with fast response and recovery rates, high sensor responses and stability are crucial. There is a need for alternative catalysts to reduce the use of expensive catalysts. A high surface to volume ratio with complete adsorption and desorption of ions makes molybdenum disulfide (MoS2) a promising catalyst in hydrogen gas sensors. A sensor with a zinc oxide (ZnO) active layer and an MoS2 nanosheet (NS) catalyst bridged between the patterned silver (Ag) electrodes was fabricated. The experimental results were comparatively very good in two ways: 1) The sensor response was high, 2) the response rate for 100 ppm H2 gas was 7 s, and the recovery rate was 23 s at 250 °C with extremely high error-free repeatability. The stability of the device was noteworthy. This cost-effective, high-performance device structure can be used as a practical industrial sensor. © 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.
... Supercapacitors are devices with long cycle life and the ability of high energy storage and high power. The capacitive method is used for energy storage, gas detection and measurement of electrical properties of water liquids [1][2][3][4][5][6][7][8][9][10][11][12]. A supercapacitor involves electrodes, electrolyte, and a separator. ...
Background:
In this paper, the supercapacitor based on the carbon nanotubes (CNTs) electrodes has been fabricated.
Objective:
The Polyvinylidene Fluoride (PVDF) and Polyvinyl Alcohol (PVA) were used as a gel electrolyte.
Methods:
The electrodes and electrolytes thin films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The specific Capacitance (Cs) of the CNTs-based supercapacitor has been measured using the cyclic voltammetry and galvanostatic methods. For the scan rate, 20 mV s-1 the Cs of the CNTs-based supercapacitor was 173 F g-1.
Results:
Using the electrochemical impedance spectroscopy the Nyquist curve has been plotted. The reactance capacitance and the equivalent series resistance of the CNTs-based supercapacitor with PVDF/PVA gel electrolytes were 90 Ω and 25 Ω respectively.
Conclusion:
Also, few patents for the CNTs-based supercapacitor have been reviewed and cited. The CNTs-based supercapacitor proposed a new structure solid-state and flexible supercapacitor with high performance.
... The current-voltage (I-V) measurements were taken from −1 V to +1 V and the resistance values were calculated from the slope of the plot through the least square method. The response (S%) of SnS nanoflakes-based humidity sensor is defined as the percent change in resistance [30][31][32][33][34]. S%=(ΔR/R x )× 100, where ΔR=(R dry -R x ), R dry and R x are the resistance of the sensor at dry air (3% RH) and x% RH, respectively. ...
Humidity sensors based on flexible sensitive nanomaterials are very attractive in noncontact healthcare monitoring. However, the existing humidity sensors have some shortcomings such as limited sensitivity, narrow relative humidity (RH) range, and a complex process. Herein, we show that a tin sulphide (SnS) nanoflakes-based sensor presents high humidity sensing behaviour both in rigid and flexible substrate. The sensing mechanism based on the Schottky nature of a SnS-metal contact endows the as-fabricated sensor with a high response of 2491000% towards a wide RH range from 3% RH to 99% RH. The response and recovery time of the sensor are 6 s and 4 s, respectively. Besides, the flexible SnS nanoflakes-based humidity sensor with a polyimide substrate can be well attached to the skin and exhibits stable humidity sensing performance in the natural flat state and under bending loading. Moreover, the first-principles analysis is performed to prove the high specificity of SnS to the moisture (H2O) in the air. Benefiting from its promising advantages, we explore some application of the SnS nanoflakes-based sensors in detection of breathing patterns and non-contact finger tips sensing behaviour. The sensor can monitor the respiration pattern of a human being accurately, and recognize the movement of the fingertip speedily. This novel humidity sensor shows great promising application in physiological and physical monitoring, portable diagnosis system, and noncontact interface localization.
... Hydrogen provides clean energy for the aerospace equipment or underwater equipment and oxygen affords the life security. There are also many dangerous situations caused by hydrogen leakage in the aircraft and submarines [2][3]. In order to ensure the safety of the working environment and prevent explosion risks, it is essential to monitor the concentration of hydrogen quantitatively. ...
The flammable and explosive property of hydrogen is the main danger in its safe use, storage and transportation. In this paper, a novel hydrogen monitoring system is designed based on the principle of semiconductor, catalytic combustion and heat-conducting gas sensors. Also, the gas sensor will inevitably fail due to the nature of gas sensitive materials in the long-time monitoring process. To ensure the accuracy and reliability of hydrogen concentration measurement, a novel fault diagnosis and reconfiguration strategy for hydrogen sensor array based on moving window principle component analysis and extreme learning machine (MWPCA-ELM) is proposed. Firstly, online multiple faults detection is carried out by using MWPCA. Once one or multiple faults are detected, the measured values of other fault-free sensors will be used to recover the faulty data in real-time by using ELM predictor according to the relevancy among the hydrogen sensors. Secondly, the hydrogen concentration is reconfigured seamlessly and accurately based on ELM under the condition of small calibration data sample. Finally, fault diagnosis is conducted by MWPCA feature extraction coupled with ELM multi-classifier. In order to illustrate the effectiveness and feasibility of the proposed fault diagnosis and reconfiguration strategy, a hydrogen concentration monitoring experimental system was established. The average relative error (ARE) of hydrogen concentration estimation is declined from 1.18% to 0.82% compared with the traditional regression methods. Particularly, the proposed fault reconfiguration model can recover the fault data even if the concentration is changed, and the accuracy of fault diagnosis is 100% within 250 samples.
... Capacitive sensors convert the electrical signals to the electrical capacitance/ conductivity. Capacitive sensors widely are used for electrical properties measurement of water solutions and mixtures and in leak detection of gases Behzadi and Golnabi, 2009;Behzadi and Golnabi, 2010;Behzadi and Fekri, 2013;Behzadi Pour and Fekriaval, 2017;Behzadi Pour, 2017;Behzadi Pour and Fekriaval, 2017;Behzadi Pour and Fekriaval, 2018;Behzadi Pour et al., 2018b). The first report of performance and principle of hydrogen gas sensor based on MOS structure was published by Lundstrom et al. (1975b) and Lundstrom and Shivaraman (1975a). ...
Purpose
This study aims to investigate the fabrication of hydrogen gas sensor based on metal–oxide–semiconductor (MOS) microstructure. The palladium nanoparticles (PdNPs) as gate metal have been deposited on the oxide film using spin coating.
Design/methodology/approach
The PdNPs and the surface of oxide film were analyzed using Transmission electron microscopy. The capacitance-voltage (C-V) curves for the MOS sensor in 1, 2 and 4 per cent hydrogen concentration and in 100 KHz frequency at the room temperature were reported.
Findings
The response times for 1, 2 and 4 per cent hydrogen concentration were 2.5 s, 1.5 s and 1 s, respectively. The responses (R per cent) of MOS sensor to 1, 2 and 4 per cent hydrogen concentration were 42.8, 47.3 and 52.6 per cent, respectively.
Originality/value
The experimental results demonstrate that the MOS hydrogen gas sensor based on the PdNPs gate, shows the fast response and recovery compared to other hydrogen gas sensors based on the Pd.
... Supercapacitors and capacitors, because of high sensitivity, depending on the capacitive method, are used in many sensors for measurement of the electrical properties, e.g., permittivity and conductivity of liquids [7][8][9][10][11] and detection/monitoring of gas leaks in air [12][13][14][15][16][17][18][19][20][21]. Supercapacitors based on the charge storage mechanism are classified into electrical double-layer capacitors (energy storage at the electrode/ electrolyte interface), pseudocapacitors (energy storage via Faradic reactions), and hybrid supercapacitors [22][23][24][25]. ...
Supercapacitors have exhibited the proper characteristics and advantages in many applications such as medical and electronic usages. Among electrolytes used in the supercapacitor structures, poly (vinyl alcohol) (PVA)-based ones have especially attracted many attentions from researchers and industrial men that this can be attributed to the solubility, biodegradability, and biocompatibility of this hydrophile polymer. For these reasons, we aimed to review the reported studies on PVA usages in supercapacitors because PVA and its composites, blends, and derivatives were frequently applied in the structure of supercapacitors as both the suitable gel electrolyte and electrode.
... There are eight commercially types of hydrogen gas sensors. These sensors are based on physical parameters, e.g., the resistance, thermal conductivity, acoustic, mechanical, optical, electrochemical and catalytic and work function [6,7]. Palladium, nickel, platinum and their composites are used as active elements in many hydrogen gas sensors. ...
Hydrogen sensors are transducer devices and able to convert the hydrogen concentration in the environment to an electrical signal. The detection and monitoring of hydrogen gas under the explosive limit is the essential issue for its applications as the chemical reactant and energy resource. In this study, the sensing mechanism and principle of the palladium-based hydrogen gas sensors are firstly reported. Then, the physical sensing parameter, measuring range, response time and recovery time of the different hydrogen gas sensors are also reviewed. Moreover, the high response speed hydrogen sensors are introduced for practical usages.
