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11 – 20 of over 4000Shweta , Sunil Jadav and Rohit Tripathi
Sensing technology has been extensively researched and used due to its applications in industrial production and daily life. Due to inherent limitations of conventional…
Abstract
Purpose
Sensing technology has been extensively researched and used due to its applications in industrial production and daily life. Due to inherent limitations of conventional silicon-based technology, researchers are now-a-days paying more attention to flexible electronics to design low-cost, high-sensitivity devices. This observational and analytical study aims to emphasis on carbon monoxide gas sensor. This review also focuses the challenges faced by flexible devices, offers the most recent research on paper-based gas sensors and pays special focus on various sensing materials and fabrication techniques.
Design/methodology/approach
To get the better insight into opportunities for future improvement, a number of research papers based on sensors were studied and realized the need to design carbon monoxide gas sensor. A number of parameters were then gone through to decide the flexibility parameter to be considered for design purposes. This review also focuses on the challenges faced by flexible devices and how they can be overcome.
Findings
It has been shown that carbon monoxide gas, being most contaminated gas, needs to be fabricated to sense low concentration at room temperature, considering flexibility as an important parameter. Regarding this parameter, some tests must be done to test whether the structure sustains or degrades after bending. The parameters required to perform bending are also described.
Originality/value
Due to inherent limitations of conventional silicon-based technology, now-a-days attention is paid towards flexible electronics to design low-cost, high-sensitivity devices. A number of research articles are provided in the literature concerning gas sensing for different applications using several sensing principles. This study aims to provide a comprehensive overview of recent developments in carbon monoxide gas sensors along with the design possibilities for flexible paper-based gas sensors. All the aspects have been taken into consideration for the fabrication, starting with paper characterization techniques, various sensing materials, manufacturing methodologies, challenges in the fabrication of flexible devices and effects of bending and humidity on the sensing performance.
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Srinivas Rao Sriram, Saidireddy Parne, Venkata Satya Chidambara Swamy Vaddadi, Damodar Edla, Nagaraju P., Raji Reddy Avala, Vijayakumar Yelsani and Uday Bhasker Sontu
This paper aims to focus on the basic principle of WO3 gas sensors to achieve high gas-sensing performance with good stability and repeatability. Metal oxide-based gas sensors are…
Abstract
Purpose
This paper aims to focus on the basic principle of WO3 gas sensors to achieve high gas-sensing performance with good stability and repeatability. Metal oxide-based gas sensors are widely used for monitoring toxic gas leakages in the environment, industries and households. For better livelihood and a healthy environment, it is extremely helpful to have sensors with higher accuracy and improved sensing features.
Design/methodology/approach
In the present review, the authors focus on recent synthesis methods of WO3-based gas sensors to enhance sensing features towards toxic gases.
Findings
This work has proved that the synthesis method led to provide different morphologies of nanostructured WO3-based material in turn to improve gas sensing performance along with its sensing mechanism.
Originality/value
In this work, the authors reviewed challenges and possibilities associated with the nanostructured WO3-based gas sensors to trace toxic gases such as ammonia, H2S and NO2 for future research.
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Lun‐Chen Hsu, Thermpon Ativanichayaphong, Hung Cao, Jeongsik Sin, Mason Graff, Harry E. Stephanou and J.‐C. Chiao
Selection of a gas sensor requires consideration of environmental effects that can significantly affect performance and cause false alarms. Metal‐oxide sensors have high…
Abstract
Purpose
Selection of a gas sensor requires consideration of environmental effects that can significantly affect performance and cause false alarms. Metal‐oxide sensors have high sensitivity due to the specific interactions of gas molecules with thin metal‐oxide films, however, the films can also be sensitive to variations in temperature and humidity and some oxidizing and deoxidizing gases. The purpose of this paper is to evaluate the environmental effect on metal‐oxide nitrogen dioxide (NO2) sensors quantitatively.
Design/methodology/approach
Three commercial metal‐oxide NO2 sensors and one electrochemical sensor were tested simultaneously under controlled gas concentrations and various environmental conditions. For this test, a customized sensor testing setup was prepared including a gas mixer, heating module, gas chamber, electronics, and data acquisition units.
Findings
Based on the test results for NO2 gas concentrations ranging from 0 to 10 ppm, the metal‐oxide sensors showed significant signal variations at elevated temperatures and humidity. The results provide overall sensor performance. Linearity, repeatability, selectivity and sensitivity of the metal‐oxide sensors were measured and compared to an electrochemical sensor.
Originality/value
A systematic evaluation to characterize metal‐oxide NO2 sensors is presented, and their comparison regarding sensitivity, selectivity, linearity, and dependence on humidity and temperature is reported. The result provides sensor performance data and guideline for sensor evaluation.
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This paper aims to show how a range of new and emerging applications are driving technological innovations in gas sensing.
Abstract
Purpose
This paper aims to show how a range of new and emerging applications are driving technological innovations in gas sensing.
Design/methodology/approach
Following a short introduction, this paper first considers developments relating to the needs of the military and security sectors. Wearable gas sensors, energy harvesting and self-powered gas sensors are then discussed. The role of gas sensors in mobile phones is then considered, together with details of new developments in sensors for carbon-dioxide, particulates and formaldehyde. Finally, brief conclusions are drawn.
Findings
This paper shows that a technologically diverse range of gas sensors is being investigated and developed in response to a number of new and emerging requirements and applications. The gas sensors respond to numerous inorganic and organic gases and vapours over a wide range of application-specific concentrations and are based on a multitude of often innovative sensing techniques, technologies and materials.
Originality/value
This paper provides technical details of a selection of gas sensor research activities and product developments that reflect the needs of a range of new and emerging applications.
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Output stability or drift overtime has long been a major performance deficiency for gas sensors irrespective of what technology or methodology is used for their conception…
Abstract
Purpose
Output stability or drift overtime has long been a major performance deficiency for gas sensors irrespective of what technology or methodology is used for their conception. Software correction may alleviate the problem somewhat but it is not always applicable. It has long been the objective of many researchers in this field to overcome this problem fundamentally and for good. The purpose of this paper is to show that this objective has now finally been achieved.
Design/methodology/approach
Conventional non‐dispersive infrared (NDIR) dual beam methodology utilizes the ratio of signal channel output over reference channel output for signal processing. The signal filter overlaps the absorption band of the gas of interest while the reference filter does not. However, this ratio changes as the source ages. The current methodology uses an absorption bias between signal and reference channel outputs. This absorption bias is created by using a path length for the signal channel greater than that for the reference channel. Both the signal and reference detectors carry an identical spectral filter overlapping the absorption band of the gas to be measured.
Findings
Implementation of the currently patented NDIR gas‐sensing methodology has been carried out in different gas sensor configurations for over a year in the laboratory. Performance results for these sensors showing insignificant output drifts overtime have been repeatedly demonstrated via simulated aging for the source.
Originality/value
The paper puts forward the view that the recent breakthrough of the Near Zero Drift methodology for NDIR gas sensors will very quickly change the hierarchy of technology dominance and utility for gas sensors at large.
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Janusz Marek Smulko, Maciej Trawka, Claes Goran Granqvist, Radu Ionescu, Fatima Annanouch, Eduard Llobet and Laszlo Bela Kish
– This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors.
Abstract
Purpose
This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors.
Design/methodology/approach
This paper compares various methods of improving gas sensing by temperature modulation, UV irradiation or fluctuation-enhanced sensing. The authors analyze low-frequency resistance fluctuations in commercial Taguchi gas sensors and the recently developed tungsten trioxide (WO3) gas-sensing layers, exhibiting a photo-catalytic effect.
Findings
The efficiency of using low-frequency fluctuations to improve gas detection selectivity and sensitivity was confirmed by numerous experimental studies in commercial and prototype gas sensors.
Research limitations/implications
A more advanced measurement setup is required to record noise data but it will reduce the number of gas sensors necessary for identifying the investigated gas mixtures.
Practical implications
Fluctuation-enhanced sensing can reduce the energy consumption of gas detection systems and assures better detection results.
Originality/value
A thorough comparison of various gas sensing methods in resistance gas sensors is presented and supported by exemplary practical applications.
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Syafiqah Ishak, Shazlina Johari, Muhammad Mahyiddin Ramli and Darminto Darminto
This review aims to give an overview about zinc oxide (ZnO) based gas sensors and the role of doping in enhancing the gas sensing properties. Gas sensors based on ZnO thin film…
Abstract
Purpose
This review aims to give an overview about zinc oxide (ZnO) based gas sensors and the role of doping in enhancing the gas sensing properties. Gas sensors based on ZnO thin film are preferred for sensing applications because of their modifiable surface morphology, very large surface-to-volume ratio and superior stability due to better crystallinity. The gas detection mechanism involves surface reaction, in which the adsorption of gas molecules on the ZnO thin film affects its conductivity and reduces its electrical properties. One way to enhance the gas sensing properties is by doping ZnO with other elements. A few of the common and previously used dopants include tin (Sn), nickel (Ni) and gallium (Ga).
Design/methodology/approach
In this brief review, previous works on doped-ZnO formaldehyde sensing devices are presented and discussed.
Findings
Most devices provided good sensing performance with low detection limits. The reported operating temperatures were within the range of 200̊C –400̊C. The performance of the gas sensors can be improved by modifying their nanostructures and/or adding dopants.
Originality/value
As of yet, a specific review on formaldehyde gas sensors based on ZnO metal semiconductors has not been done.
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Yong Pan, Qin Molin, Tengxiao Guo, Lin Zhang, Bingqing Cao, Junchao Yang, Wen Wang and Xufeng Xue
This paper aims to give an overview about the state of wireless passive surface acoustic wave (SAW) gas sensor used in the detection of chemical vapor. It also discusses a variety…
Abstract
Purpose
This paper aims to give an overview about the state of wireless passive surface acoustic wave (SAW) gas sensor used in the detection of chemical vapor. It also discusses a variety of different architectures including delay line and array sensor for gas detection, and it is considered that this technology has a good application prospect.
Design/methodology/approach
The authors state the most of the wireless passive SAW methods used in gas sensing, such as CO2, CO, CH4, C2H4, NH3, NO2, et al., the sensor principles, design procedures and technological issues are discussed in detail; their advantages and disadvantages are also summarized. In conclusion, it gives a prospect of wireless passive SAW sensor applications and proposes the future research field might lie in the studying of many kinds of harmful gases.
Findings
In this paper, the authors will try to cover most of the important methods used in gas sensing and their recent developments. Although wireless passive SAW sensors have been used successfully in harsh environments for the monitoring of temperature or pressure, the using in chemical gases are seldom reported. This review paper gives a survey of the present state of wireless passive SAW sensor in gas detection and suggests new and exciting perspectives of wireless passive SAW gas sensor technology.
Research limitations/implications
The authors will review most of the methods used in wireless passive SAW sensor and discuss the current research status and development trend; the potential application in future is also forecasted.
Originality/value
The authors will review most of the methods used in wireless passive SAW sensor and discuss the current research status and development trend; the potential application in future is also forecasted.
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Chinmay Roy, Aparna Ghosh and Suman Chatterjee
This paper aims to estimate the relationship between defect structure with gas concentration for use as a gas sensor. The change in defect concentration caused a shift in the…
Abstract
Purpose
This paper aims to estimate the relationship between defect structure with gas concentration for use as a gas sensor. The change in defect concentration caused a shift in the Fermi level, which in turn changed the surface potential, which is manifested as the potentiometric response of the sensing element.
Design/methodology/approach
A new theoretical concept based on defect chemistry and band structure was used to explain the experimental gas response of a sensor. The theoretically simulated response was compared with experimental results.
Findings
Understanding the origin of potentiometric response, through the generation of defects and a corresponding shift in Fermi level of sensing surface, by the adsorption of gas. Through this understanding, the design of a sensor with improved selectivity and stability to a gas can be achieved by the study of defect structure and subsequent band analysis.
Research limitations/implications
This paper provides information about various types of surface defects and numerical simulation of material with defect structure. The Fermi energy of the simulated value is correlated with the potentiometric sensor response.
Practical implications
Gas sensors are an integral part of vehicular and industrial pollution control. The theory developed shows the origin of response which can help in identifying the best sensing material and its optimum temperature of operation.
Social implications
Low-cost, reliable and highly sensitive gas sensors are highly demanded which is fulfilled by potentiometric sensors.
Originality/value
The operating principle of potentiometric sensors is analyzed through electron band structure analysis. With the change in measured gas concentration, the oxygen partial pressure changes. This results in a change in defect concentration in the sensing surface. Band structure analysis shows that change in defect concentration is associated with a shift in Fermi level. This is the origin of the potentiometric response.
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Rabeb Faleh, Sami Gomri, Khalifa Aguir and Abdennaceur Kachouri
The purpose of this paper is to deal with the classification improvement of pollutant using WO3 gases sensors. To evaluate the discrimination capacity, some experiments were…
Abstract
Purpose
The purpose of this paper is to deal with the classification improvement of pollutant using WO3 gases sensors. To evaluate the discrimination capacity, some experiments were achieved using three gases: ozone, ethanol, acetone and a mixture of ozone and ethanol via four WO3 sensors.
Design/methodology/approach
To improve the classification accuracy and enhance selectivity, some combined features that were configured through the principal component analysis were used. First, evaluate the discrimination capacity; some experiments were performed using three gases: ozone, ethanol, acetone and a mixture of ozone and ethanol, via four WO3 sensors. To this end, three features that are derivate, integral and the time corresponding to the peak derivate have been extracted from each transient sensor response according to four WO3 gas sensors used. Then these extracted parameters were used in a combined array.
Findings
The results show that the proposed feature extraction method could extract robust information. The Extreme Learning Machine (ELM) was used to identify the studied gases. In addition, ELM was compared with the Support Vector Machine (SVM). The experimental results prove the superiority of the combined features method in our E-nose application, as this method achieves the highest classification rate of 90% using the ELM and 93.03% using the SVM based on Radial Basis Kernel Function SVM-RBF.
Originality/value
Combined features have been configured from transient response to improve the classification accuracy. The achieved results show that the proposed feature extraction method could extract robust information. The ELM and SVM were used to identify the studied gases.
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