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Topical Collection "Gas Sensors"

Editor

Collection Editor
Prof. Dr. Giovanni Neri

Department of Electronic Engineering, Chemistry and Industrial Engineering, University of Messina, 98166 Messina, Italy
Website | E-Mail
Fax: +39 090 397 7464
Interests: chemical synthesis of sensing materials; oxide semiconductor-based gas sensors; nanostructures for chemical and electrochemical sensing; automotive gas sensors; biomedical sensors

Topical Collection Information

Dear Colleagues,

Gas sensors play an important role in many aspects of technology, in fields such as industrial processes, automotive technologies, environmental monitoring, or air quality assurance, to name just a few, and are increasingly becoming part of our day-to-day lives at work and home. Today’s devices exploit numerous solid-state, electrochemical, optical and other phenomena related to gas sensing. Research and development of gas sensor devices continue to be faced with numerous challenges in terms of sensitivity, selectivity, stability, and many other aspects. Thus, while the fundamental understanding of underlying sensing processes continues to improve, the discovery of novel functional sensing materials open up new opportunities, the format/architecture of gas sensors is rapidly changing. In recent decades, the evolution of sensors has been strongly influenced by ICT technologies, with integration of microcontrollers, wireless communications modules, and permanent data storage. New sensing technology platforms provide the ability to monitor, control, optimize, and provide autonomy to smart, connected devices, enabled by advances in component miniaturization, microelectromechanical systems (MEMS), low-power devices, onboard processing, and Internet-connected “cloud” computing.  

This Topical Collection on 'Gas Sensors' aims to cover the above-mentioned aspects regarding gas sensors. Key issues, such as the developments of novel gas sensing materials, new insights in gas sensing mechanisms, new devices and fabrication technologies, testing and characterization of micro- and nano-fabricated systems for gas sensing, are, therefore, collected together to give an overview of the recent fundamental and applied research carried out in this field. Topics covered are:

  • Gas sensing materials
  • Principles and phenomena of gas sensing
  • Gas-sensing mechanisms
  • Gas sensor technologies
  • Micro- and nanofabrication
  • Applications

Prof. Dr. Giovanni Neri
Collection Editor

Manuscript Submission Information

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Published Papers (7 papers)

2017

Open AccessArticle A Study of the CO Sensing Responses of Cu-, Pt- and Pd-Activated SnO2 Sensors: Effect of Precipitation Agents, Dopants and Doping Methods
Sensors 2017, 17(5), 1011; doi:10.3390/s17051011
Received: 27 February 2017 / Revised: 25 April 2017 / Accepted: 27 April 2017 / Published: 3 May 2017
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Abstract
In this work, we report the synthesis of Cu, Pt and Pd doped SnO2 powders and a comparative study of their CO gas sensing performance. Dopants were incorporated into SnO2 nanostructures using chemical and impregnation methods by using urea and ammonia
[...] Read more.
In this work, we report the synthesis of Cu, Pt and Pd doped SnO2 powders and a comparative study of their CO gas sensing performance. Dopants were incorporated into SnO2 nanostructures using chemical and impregnation methods by using urea and ammonia as precipitation agents. The synthesized samples were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The presence of dopants within the SnO2 nanostructures was evidenced from the HR-TEM results. Powders doped utilizing chemical methods with urea as precipitation agent presented higher sensing responses compared to the other forms, which is due to the formation of uniform and homogeneous particles resulting from the temperature-assisted synthesis. The particle sizes of doped SnO2 nanostructures were in the range of 40–100 nm. An enhanced sensing response around 1783 was achieved with Cu-doped SnO2 when compared with two other dopants i.e., Pt (1200) and Pd:SnO2 (502). The high sensing response of Cu:SnO2 is due to formation of CuO and its excellent association and dissociation with adsorbed atmospheric oxygen in the presence of CO at the sensor operation temperature, which results in high conductance. Cu:SnO2 may thus be an alternative and cost effective sensor for industrial applications. Full article
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Open AccessFeature PaperArticle Non-Gaussian Resistance Fluctuations in Gold-Nanoparticle-Based Gas Sensors: An Appraisal of Different Evaluation Techniques
Sensors 2017, 17(4), 757; doi:10.3390/s17040757
Received: 18 February 2017 / Revised: 30 March 2017 / Accepted: 31 March 2017 / Published: 3 April 2017
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Abstract
Volatile organic compounds, such as formaldehyde, can be used as biomarkers in human exhaled breath in order to non-invasively detect various diseases, and the same compounds are of much interest also in the context of environmental monitoring and protection. Here, we report on
[...] Read more.
Volatile organic compounds, such as formaldehyde, can be used as biomarkers in human exhaled breath in order to non-invasively detect various diseases, and the same compounds are of much interest also in the context of environmental monitoring and protection. Here, we report on a recently-developed gas sensor, based on surface-functionalized gold nanoparticles, which is able to generate voltage noise with a distinctly non-Gaussian component upon exposure to formaldehyde with concentrations on the ppm level, whereas this component is absent, or at least much weaker, when the sensor is exposed to ethanol or to pure air. We survey four different statistical methods to elucidate a non-Gaussian component and assess their pros and cons with regard to efficient gas detection. Specifically, the non-Gaussian component was clearly exposed in analysis using level-crossing parameters, which require nothing but a modest computational effort and simple electronic circuitry, and analogous results could be reached through the bispectrum function, albeit with more intense computation. Useful information could be obtained also via the Lévy-stable distribution and, possibly, the second spectrum. Full article
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Open AccessArticle Gas Sensor Based on 3-D WO3 Inverse Opal: Design and Applications
Sensors 2017, 17(4), 710; doi:10.3390/s17040710
Received: 12 February 2017 / Revised: 21 March 2017 / Accepted: 21 March 2017 / Published: 29 March 2017
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Abstract
A three-dimensional inverse opal (3DIO) WO3 architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the
[...] Read more.
A three-dimensional inverse opal (3DIO) WO3 architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the PMMA spheres was ~28.2% through measuring the distribution of the PMMA spheres and 3DIO WO3 center-to-center distance between the spheres and macropores, respectively. Beyond that, the 3DIO gas sensing properties were investigated systematically and the sensing mechanism of 3DIO WO3 was proposed. The results indicated that the response of the 3DIO sensor possessed excellent sensitivity to acetone gas, especially at trace levels. The 3DIO gas sensor response was ~7 to 5 ppm of acetone and could detect acetone low to 0.2 ppm effectively, which was in close proximity to the theoretical low detection limit of 0.14 ppm when Ra/Rg ≥ 1.2 was used as the criterion for reliable gas sensing. All in all, the obvious satisfaction of the gas-sensing properties was ascribed to the structure of the 3DIO, and the sensor could be a promising novel device in the future. Full article
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Open AccessReview Electrodes for Semiconductor Gas Sensors
Sensors 2017, 17(4), 683; doi:10.3390/s17040683
Received: 7 February 2017 / Revised: 11 March 2017 / Accepted: 22 March 2017 / Published: 25 March 2017
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Abstract
The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and
[...] Read more.
The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. Full article
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Open AccessArticle Ratiometric Dissolved Oxygen Sensors Based on Ruthenium Complex Doped with Silver Nanoparticles
Sensors 2017, 17(3), 548; doi:10.3390/s17030548
Received: 28 December 2016 / Revised: 19 February 2017 / Accepted: 6 March 2017 / Published: 9 March 2017
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Abstract
A ratiometric optical sensor has been developed with electrospinning processing method for dissolved oxygen measurement. The sensing film is fabricated by using silver nano-particles (Ag NPs) doped with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex (Ru(DPP)3Cl2) encapsulated in plasticized polymethyl methacrylate (PMMA).
[...] Read more.
A ratiometric optical sensor has been developed with electrospinning processing method for dissolved oxygen measurement. The sensing film is fabricated by using silver nano-particles (Ag NPs) doped with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex (Ru(DPP)3Cl2) encapsulated in plasticized polymethyl methacrylate (PMMA). An insensitive 3-(2-benzothiazolyl)-7-(diethy lamino)-(6CI,7CI) (Coumarin6) is adopted as reference. The ratio of oxygenation is calculated at each image pixel of a 3CCD camera to quantify the oxygen concentration in aqueous environment. Compared to Ag-free film, the response time of Ag-containing films were improved from 1.5 s to 1.0 s upon switching from deoxygenated to air saturation and from 65 s to 45 s from air saturation to fully deoxygenated. The response times of the Ag-free film obtained by knifing was 2.0 s upon switching from deoxygenated to air saturation and 104 s from air saturation to fully deoxygenated. Results of the evaluation of accuracy, limit of detection, stability, and photostability are presented. An experiment measuring the spatiotemporal variation of oxygen distribution within the photosynthesis and respiration of Chlorella vulgaris is demonstrated. It is shown that the nanofiber-based optical sensor film could serve as a promising method for rapid oxygen monitoring in aqueous applications. Full article
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Open AccessArticle Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts
Sensors 2017, 17(2), 400; doi:10.3390/s17020400
Received: 20 November 2016 / Revised: 29 January 2017 / Accepted: 11 February 2017 / Published: 18 February 2017
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Abstract
Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies
[...] Read more.
Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor. Full article
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Open AccessArticle Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection
Sensors 2017, 17(2), 303; doi:10.3390/s17020303
Received: 21 November 2016 / Revised: 18 January 2017 / Accepted: 3 February 2017 / Published: 7 February 2017
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Abstract
A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique
[...] Read more.
A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection. Full article
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