scholarly journals Insights about CO Gas-Sensing Mechanism with NiO-Based Gas Sensors—The Influence of Humidity

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 244
Author(s):  
Cristian E. Simion ◽  
Corneliu Ghica ◽  
Catalina G. Mihalcea ◽  
Daniela Ghica ◽  
Ionel Mercioniu ◽  
...  
Keyword(s):  
Work Function ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Unusual Behavior ◽  
Detection Mechanism ◽  
Band Bending ◽  
Hollow Structures ◽  
Adsorption Sites ◽  
Moisture Influence ◽  
Co Detection

Polycrystalline NiO thick film-based gas sensors have been exposed to different test gas atmospheres at 250 °C and measured via simultaneous electrical resistance and work function investigations. Accordingly, we decoupled different features manifested toward the potential changes, i.e., work function, band-bending, and electron affinity. The experimental results have shown that the presence of moisture induces an unusual behavior toward carbon monoxide (CO) detection by considering different surface adsorption sites. On this basis, we derived an appropriate detection mechanism capable of explaining the lack of moisture influence over the CO detection with NiO-sensitive materials. As such, CO might have both chemical and dipolar interactions with pre-adsorbed or lattice oxygen species, thus canceling out the effect of moisture. Additionally, morphology, structure, and surface chemistry were addressed, and the results have been linked to the sensing properties envisaging the role played by the porous quasispherical–hollow structures and surface hydration.

Thermal detection mechanism of SiC-Based Resistive Gas Sensors

2006 ◽  
Vol 911 ◽  
Author(s):  
Timothy J. Fawcett ◽  
Meralys Reyes ◽  
Anita Lloyd Spetz ◽  
Stephen E. Saddow ◽  
John T. Wolan
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Thermal Contact ◽  
Detection Mechanism ◽  
First Order ◽  
Sensing Mechanism ◽  
Temperature Detector ◽  
Dc Bias ◽  
Thermal Detection ◽  
Resistive Gas Sensors

AbstractSilicon carbide-based resistive gas sensors from our laboratory have been previously reported to detect hydrogen at concentrations ranging from less than 1% to 100% H2 in Ar and at temperatures ranging from 50°C to 450°C. The gas sensing mechanism for these devices was not well understood, hindering further improvement in this technology. In this report, resistive devices built on a thin 3C-SiC epitaxial layer grown on 150Å thick Si layer wafer bonded to a polycrystalline SiC substrate were studied. The polycrystalline SiC substrate is insulating, allowing the formation of isolated epitaxy resistors on the 3C-SiC layer. The gas sensing devices consisted of rectangular ohmic NiCr contacts with a Au overlayer fabricated on the 3C-SiC surface. Under a constant dc bias, nominally 10V in this study, these sensors demonstrated a decrease in current of up to ~25.4 mA upon the introduction of 100% H2, relative to 100% N2 in the test gas stream. The time constant for this device, estimated as a first-order exponential decay, was ~16-22 sec, with the full response occurring after ~90-120 sec. Upon the introduction of 100% H2 to the sensing environment, the device temperature, as measured by an resistance temperature detector (RTD) in intimate thermal contact with the device, decreased from 400°C to 237°C (ΔT = ~163°C). This large decrease in device temperature was driven by increased heat transfer coefficient of H2 relative to N2. The sensitivity to CH4 in N2, CO2 in N2 and He in Ar was also tested. Sensitivities, defined as the smallest change in concentration, as low as 300 ppm H2 in N2 were achieved with devices operating at 400°C and 10 V dc. Details of the device performance and a model of the sensing mechanism will be discussed.

scholarly journals Effect of Ag Addition on the Gas-Sensing Properties of Nanostructured Resistive-Based Gas Sensors: An Overview

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6454
Author(s):  
Sachin Navale ◽  
Mehrdad Shahbaz ◽  
Ali Mirzaei ◽  
Sang Sub Kim ◽  
Hyoun Woo Kim
Keyword(s):  
Gas Sensors ◽  
Noble Metals ◽  
Gas Sensing ◽  
Response Times ◽  
Detection Mechanism ◽  
Ag Addition ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Semiconducting Metal Oxides ◽  
The Impact

Nanostructured semiconducting metal oxides (SMOs) are among the most popular sensing materials for integration into resistive-type gas sensors owing to their low costs and high sensing performances. SMOs can be decorated or doped with noble metals to further enhance their gas sensing properties. Ag is one of the cheapest noble metals, and it is extensively used in the decoration or doping of SMOs to boost the overall gas-sensing performances of SMOs. In this review, we discussed the impact of Ag addition on the gas-sensing properties of nanostructured resistive-based gas sensors. Ag-decorated or -doped SMOs often exhibit better responsivities/selectivities at low sensing temperatures and shorter response times than those of their pristine counterparts. Herein, the focus was on the detection mechanism of SMO-based gas sensors in the presence of Ag. This review can provide insights for research on SMO-based gas sensors.

Noble metal (Ag, Au, Pd and Pt) doped TaS2 monolayer for gas sensing: a first-principles investigation

2021 ◽  
Author(s):  
Jia Shi ◽  
Wenjing Quan ◽  
Xinwei Chen ◽  
Xiyu Chen ◽  
Yongwei Zhang ◽  
...  
Keyword(s):  
Work Function ◽  
Noble Metal ◽  
Gas Sensors ◽  
First Principles ◽  
Recovery Time ◽  
High Performance ◽  
Gas Sensing ◽  
Promising Candidate ◽  
Obvious Change ◽  
Short Recovery Time

Ag-doped TaS2 monolayers show an obvious change in work function and short recovery time for NO2, which indicates that TaS2-based nanomaterials might be a promising candidate for constructing high-performance NO2 gas sensors.

scholarly journals Investigation of CO2 reaction with copper oxide nanoparticles for room temperature gas sensing

2016 ◽  
Vol 4 (14) ◽  
pp. 5294-5302 ◽  
Author(s):  
N. B. Tanvir ◽  
O. Yurchenko ◽  
Ch. Wilbertz ◽  
G. Urban
Keyword(s):  
Low Power ◽  
Copper Oxide ◽  
Work Function ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Low Cost ◽  
Copper Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Reversible Formation

CO2 sensing at room temperature: the interaction of CO2 and H2O with copper oxide nanoparticles results in reversible formation of basic carbonates. This phenomenon is the key reaction for the work function readout based CO2 sensing which enables the prospects towards low power and low cost gas sensors.

scholarly journals Improving Ammonia Detecting Performance of Polyaniline Decorated rGO Composite Membrane with GO Doping

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2829
Author(s):  
Yubin Yuan ◽  
Haiyang Wu ◽  
Xiangrui Bu ◽  
Qiang Wu ◽  
Xuming Wang ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Response Process ◽  
Ammonia Gas ◽  
Adsorption Sites ◽  
Nh3 Adsorption ◽  
Doped Polyaniline ◽  
Ammonia Gas Sensors ◽  
Gas Response ◽  
Sensing Performance

Gas-sensing performance of graphene-based material has been investigated widely in recent years. Polyaniline (PANI) has been reported as an effective method to improve ammonia gas sensors’ response. A gas sensor based on a composite of rGO film and protic acid doped polyaniline (PA-PANI) with GO doping is reported in this work. GO mainly provides NH3 adsorption sites, and PA-PANI is responsible for charge transfer during the gas-sensing response process. The experimental results indicate that the NH3 gas response of rGO is enhanced significantly by decorating with PA-PANI. Moreover, a small amount of GO mixed with PA-PANI is beneficial to increase the gas response, which showed an improvement of 262.5% at 25 ppm comparing to no GO mixing in PA-PANI.

Metal-oxide based ammonia gas sensors: A review

2020 ◽  
Vol 10 ◽  
Author(s):  
Priya Gupta ◽  
Savita Maurya ◽  
Narendra Kumar Pandey ◽  
Vernica Verma
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Review Paper ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Ammonia Gas ◽  
Ammonia Sensing ◽  
Ammonia Gas Sensors

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

scholarly journals On the Use of MOFs and ALD Layers as Nanomembranes for the Enhancement of Gas Sensors Selectivity

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1552 ◽  
Author(s):  
Weber ◽  
Graniel ◽  
Balme ◽  
Miele ◽  
Bechelany
Keyword(s):  
Thin Films ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Metal Organic Frameworks ◽  
Atomic Layer ◽  
Operational Performance ◽  
Layer Deposition ◽  
Metal Organic ◽  
Further Development ◽  
Different Gases

Improving the selectivity of gas sensors is crucial for their further development. One effective route to enhance this key property of sensors is the use of selective nanomembrane materials. This work aims to present how metal-organic frameworks (MOFs) and thin films prepared by atomic layer deposition (ALD) can be applied as nanomembranes to separate different gases, and hence improve the selectivity of gas sensing devices. First, the fundamentals of the mechanisms and configuration of gas sensors will be given. A selected list of studies will then be presented to illustrate how MOFs and ALD materials can be implemented as nanomembranes and how they can be implemented to improve the operational performance of gas sensing devices. This review comprehensively shows the benefits of these novel selective nanomaterials and opens prospects for the sensing community.

scholarly journals Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 783 ◽  
Author(s):  
Andrea Gaiardo ◽  
David Novel ◽  
Elia Scattolo ◽  
Michele Crivellari ◽  
Antonino Picciotto ◽  
...  
Keyword(s):  
Low Power ◽  
Failure Analysis ◽  
Gas Sensors ◽  
High Performance ◽  
Gas Sensing ◽  
Mechanical Failure ◽  
Sensing Applications ◽  
Theoretical Approaches ◽  
Sensing Material ◽  
Silicon Bulk

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

scholarly journals CO Detection Investigation at High Temperature by SiC MISFET Metal/Oxide Gas Sensors

Proceedings ◽  
2021 ◽  
Vol 56 (1) ◽  
pp. 41
Author(s):  
Lida Khajavizadeh ◽  
Anita Lloyd Spetz ◽  
Mike Andersson
Keyword(s):  
High Temperature ◽  
Gas Sensors ◽  
Elevated Temperatures ◽  
Long Term Stability ◽  
Stability Performance ◽  
Catalytic Metal ◽  
Co Detection ◽  
Effect Transistor ◽  
Metal Oxide Gas Sensors

In order to investigate the necessary device improvements for high-temperature CO sensing with SiC metal insulator semiconductor field effect transistor (MISFET)-based chemical gas sensors, devices employing, as the gas-sensitive gate contact, a film of co-deposited Pt/Al2O3 instead of the commonly used catalytic metal-based contacts were fabricated and characterized for CO detection at elevated temperatures and different CO and O2 levels. It can be concluded that the sensing mechanism at elevated temperatures correlates with oxygen removal from the sensor surface rather than the surface CO coverage as observed at lower temperatures. The long-term stability performance was also shown to be improved compared to that of previously studied devices.

scholarly journals Advanced development of metal oxide nanomaterials for H2 gas sensing applications

2021 ◽  
Author(s):  
Yushu Shi ◽  
Huiyan Xu ◽  
Tongyao Liu ◽  
Shah Zeb ◽  
Yong Nie ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Gas Sensing ◽  
The Past ◽  
Sensing Applications ◽  
The Future ◽  
Metal Oxide Nanomaterials ◽  
Nanomaterials Synthesis ◽  
Advanced Development

The scheme of the structure of this review includes an introduction from the metal oxide nanomaterials’ synthesis to application in H2 gas sensors—a vision from the past to the future.

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