scholarly journals Oxygen sensing with individual ZnO:Sb micro-wires: effects of temperature and light exposure on the sensitivity and stability

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Tej Poudel Chhetri ◽  
Lei Kerr ◽  
Nada Masmali ◽  
Herbert Jaeger ◽  
Khalid F. Eid
Keyword(s):  
Gas Flow ◽  
Gas Sensing ◽  
Light Exposure ◽  
Surface Reactivity ◽  
Light Illumination ◽  
Gas Sensitivity ◽  
Sensing Material ◽  
Oxygen Oxygen ◽  
Oxygen Gas ◽  
Effect Of Light

Nanostructured ZnO has been widely investigated as a gas sensing material. Antimony is an important dopant for ZnO that catalyses its surface reactivity and thus strengthens its gas sensing capability. However, there are not enough studies on the gas sensing of antimony-doped ZnO single wires. We fabricated and characterized ZnO/ZnO:Sb core–shell micro-wires and demonstrated that individual wires are sensitive to oxygen gas flow. Temperature and light illumination strongly affect the oxygen gas sensitivity and stability of these individual wires. It was found that these micro- and nano-wire oxygen sensors at 200°C give the highest response to oxygen, yet a vanishingly small effect of light and temperature variations. The underlying physics and the interplay between these effects are discussed in terms of surface-adsorbed oxygen, oxygen vacancies and hydrogen doping.

Gas Sensing Properties of Porous ZnO Nano-Platelet Films

2007 ◽  
Vol 1035 ◽  
Author(s):  
Amandeep Saluja ◽  
Jie Pan ◽  
Lei Kerr ◽  
Eunjung Cho ◽  
Seth Hubbard
Keyword(s):  
Gas Flow ◽  
Room Temperature ◽  
Gas Sensing ◽  
Electrode Spacing ◽  
Porous Films ◽  
Gas Sensitivity ◽  
Gas Sensing Properties ◽  
Recovery Times ◽  
Response And Recovery ◽  
Carrier Gas Flow

AbstractIn this work, various ZnO nanostructures were synthesized and a detailed study on the effect of different process parameters such as temperature, carrier gas flow, inter-electrode spacing, gas concentration and material properties on gas sensitivity was conducted. Initial ZnO nanoparticles were prepared by a simple solution chemical process and characterized by Secondary Electron Microscopy (SEM) and Brunauer, Emmet and Teller (BET) Sorptometer to demonstrate the morphology and surface area respectively. Sensitivity of nano-platelets and porous films was measured for different concentrations of the analytes (H2, CO). High response was observed at room temperature for H2 gas with sensitivities in excess 80% for 60ppm and about 55% for 80ppm of H2 gas at room temperature were observed for the nano-platelets and the porous films respectively with short response and recovery times of about 200 seconds. The sensitivity of the nano-platelets to CO gas was also measured and found to be about near 90% for 80 ppm CO at operating temperatures of 200 °C.

Influence of Doping on Structure and H2 Sensitivity of Nano-SnO2

2010 ◽  
Vol 96 ◽  
pp. 105-110 ◽  
Author(s):  
Hai Feng Liu ◽  
Tong Jiang Peng ◽  
Hong Juan Sun ◽  
Liang Fan ◽  
Boa Gang Guo
Keyword(s):  
Gas Sensing ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Gas Sensitivity ◽  
X Ray ◽  
Sensing Material ◽  
Crystal Properties ◽  
Co Precipitation ◽  
Special Environment ◽  
Semiconductor Properties

In order to improve the gas sensitivity of SnO2, Ni-doped and Co-doped nano-powders were prepared by the homogenous co-precipitation method using analytical pure SnCl4•5H2O and NH3•H2O as main materials under different doped ratios n (M2+)/n (Sn4+). The gas sensors were made by the thick film technique on mica substrates. The structure and crystal properties of the samples were investigated by X-ray diffraction (XRD). The results indicated that Sn4+ in the crystal lattice of SnO2 was partly replaced by M2+, which resulted in the change of the M-O bond lengths and the lattice parameters. The sensitivities of the sensors in H2 atmosphere with different concentrations at 75°C were tested. As a result, doped M2+ especially Ni2+ improves its H2 sensitivity, the sensitivities increases linearly with the increasing H2 concentration, and the best doping n(M2+)/n(Sn4+) of preparing gas-sensing material were obtained. The results show that doping which leads to the asymmetry of electrovalent balance of M-O octahedrons improves the activities and semiconductor properties of the powders. These studies play an important part in detecting reductive gases in special environment.

scholarly journals The Influence of Temperature and Visible Light Activation on the NO2 Response of WO3 Nanofibers Prepared by Electrospinning

Proceedings ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Valentina Paolucci ◽  
Seyed Mahmoud Emamjomeh ◽  
Umberto Anselmi-Tamburini ◽  
Carlo Cantalini
Keyword(s):  
Visible Light ◽  
Room Temperature ◽  
Gas Sensing ◽  
Electrical Response ◽  
Sol Gel ◽  
Electrospun Nanofibers ◽  
Slight Reduction ◽  
Light Illumination ◽  
Base Line ◽  
Gas Sensitivity

Aim of this work is to compare the electrical responses to 100–400 ppb NO2 gas concentrations of WO3 electrospun nanofibers both activated by thermal (in the temperature range 25–100 °C) and/or visible light at different wavelengths (Red λ = 670 nm, Green λ = 550 nm, and Purple-Blue λ = 430 nm). WO3 nanofibers were prepared by mixing a W-O sol-gel transparent solution with a polymeric solution made of PVP and DMF, electospun and subsequently annealed at 450 °C. Regarding gas sensing measurements, Purple Blue light resulted the most effective light source as respect to the others. Light illumination at room temperature revealed to improve both base line recovery and response time, whereas temperature enhances relative response, with a maximum at 75 °C. Light-radiating room temperature gas detection yields a satisfactory response notwithstanding a slight reduction of sensor gas sensitivity. Light induced electrical response mechanisms is presented and discussed.

scholarly journals Review: Influences of Semiconductor Metal Oxide Properties on Gas Sensing Characteristics

2021 ◽  
Vol 2 ◽  
Author(s):  
Bilge Saruhan ◽  
Roussin Lontio Fomekong ◽  
Svitlana Nahirniak
Keyword(s):  
Gas Sensing ◽  
High Surface ◽  
Synthesis Method ◽  
Wide Band ◽  
Surface Reactivity ◽  
Crystallographic Structure ◽  
Wide Band Gap ◽  
Sensing Properties ◽  
Sensing Material ◽  
Sensing Characteristics

Semiconductor metal oxides (SMOxs) are widely used in gas sensors due to their excellent sensing properties, abundance, and ease of manufacture. The best examples of these sensing materials are SnO2 and TiO2 that have wide band gap and offer unique set of functional properties; the most important of which are electrical conductivity and high surface reactivity. There has been a constant development of SMOx sensor materials in the literature that has been accompanied by the improvement of their gas-sensitive properties for the gas detection. This review is dedicated to compiling of these efforts in order to mark the achievements in this area. The main material-specific aspects that strongly affect the gas sensing properties and can be controlled by the synthesis method are morphology/nanostructuring and dopants to vary crystallographic structure of MOx sensing material.

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 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 Artificial complementary chromatic acclimation gene expression system in Escherichia coli

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Dwi Ariyanti ◽  
Kazunori Ikebukuro ◽  
Koji Sode
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Light Exposure ◽  
Expression System ◽  
Red Light ◽  
Green Light ◽  
Light Illumination ◽  
Multiple Gene ◽  
Gene Expression System ◽  
Chromatic Acclimation

Abstract Background The development of multiple gene expression systems, especially those based on the physical signals, such as multiple color light irradiations, is challenging. Complementary chromatic acclimation (CCA), a photoreversible process that facilitates the control of cellular expression using light of different wavelengths in cyanobacteria, is one example. In this study, an artificial CCA systems, inspired by type III CCA light-regulated gene expression, was designed by employing a single photosensor system, the CcaS/CcaR green light gene expression system derived from Synechocystis sp. PCC6803, combined with G-box (the regulator recognized by activated CcaR), the cognate cpcG2 promoter, and the constitutively transcribed promoter, the PtrcΔLacO promoter. Results One G-box was inserted upstream of the cpcG2 promoter and a reporter gene, the rfp gene (green light-induced gene expression), and the other G-box was inserted between the PtrcΔLacO promoter and a reporter gene, the bfp gene (red light-induced gene expression). The Escherichia coli transformants with plasmid-encoded genes were evaluated at the transcriptional and translational levels under red or green light illumination. Under green light illumination, the transcription and translation of the rfp gene were observed, whereas the expression of the bfp gene was repressed. Under red light illumination, the transcription and translation of the bfp gene were observed, whereas the expression of the rfp gene was repressed. During the red and green light exposure cycles at every 6 h, BFP expression increased under red light exposure while RFP expression was repressed, and RFP expression increased under green light exposure while BFP expression was repressed. Conclusion An artificial CCA system was developed to realize a multiple gene expression system, which was regulated by two colors, red and green lights, using a single photosensor system, the CcaS/CcaR system derived from Synechocystis sp. PCC6803, in E. coli. The artificial CCA system functioned repeatedly during red and green light exposure cycles. These results demonstrate the potential application of this CCA gene expression system for the production of multiple metabolites in a variety of microorganisms, such as cyanobacteria.

scholarly journals High-Sensitive Numerical Gas Detection Using LSPR Effect and Fano Resonance in a Slotted MDM Structure

2021 ◽  
Author(s):  
Hai Liu ◽  
Benlei Zhao ◽  
Xu Zhang ◽  
Hancheng Zhang ◽  
Bo Wu ◽  
...  
Keyword(s):  
Fano Resonance ◽  
Gas Sensing ◽  
Field Enhancement ◽  
Fast Response ◽  
Gas Detection ◽  
Localized Surface Plasmon ◽  
Gas Sensitivity ◽  
Combined Use ◽  
Coherent Coupling ◽  
Lspr Effect

AbstractA high-sensitive numerical measurement of methane based on the combined use of the localized surface plasmon resonance (LSPR) and Fano resonance in a slotted metal-dielectric-metal (MDM) periodic structure is numerically investigated. A groove is etched in an original MDM structure to excite the diploe mode at both sides of the groove, and the coherent coupling of two dipole modes is enhanced to realize a fast response, which is beneficial to gas-sensing. The influence of geometric parameters on the reflection spectra and methane sensitivity are analyzed to obtain optimal geometry. Moreover, an etching ring is introduced on the top metal to further raise the coupling area and coupling strength. The Fano resonance is subtly integrated into the optimized structure with asymmetry to achieve greater gas sensitivity. After the introduction of the Fano resonance, the field enhancement caused by the LSPR effect becomes greater and the methane sensitivity can reach up to 8.421 nm/% in numerical calculations, which increases 56.8% more than that of the original one. The combined use of the LSPR and Fano resonance in an optimized MDM structure provides an effective method for high-sensitive gas detection.

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