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Special Issue "Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Chemical Sensors".

Deadline for manuscript submissions: closed (10 December 2022) | Viewed by 6438

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Special Issue Editors

Dr. Emiliano Zampetti

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Guest Editor

CNR-Institute of Atmospheric Pollution Research, V. Salaria Km 29,300, Monterotondo, 00015 Rome, Italy
Interests: sensors and sensor systems for air pollution monitoring

Dr. Fabrizio Dirri

E-Mail Website
Guest Editor

Institute for Space Astrophysics and Planetology IAPS, 00133 Rome, Italy
Interests: piezoelectric sensors; thermogravimetric analysis; contamination monitoring; organic compounds characterization; space mission instrumentations; QCM sensors

Special Issue Information

Dear Colleagues,

Gas sensors, physical sensors, and sensor systems such as electronic noses play an increasingly important role in everyday life. In fact, they regulate our travels or methods of travel in big cities, providing data to regulate vehicle traffic. In indoor environments such as the home, their data are necessary for air conditioning systems to optimize their operation, taking into account air quality and energy consumption. Sensors will play an important role in human extraterrestrial voyages, to monitor the quality of air in the spacecraft or in space stations. Currently, physical sensors in space monitor the dust or contamination of the outdoor surface of the crew cabin or satellite parts to control the integrity or to prevent possible structural problems.

This Special Issue welcomes the submission of both review and original research articles related to recent or consolidated technology (materials or devices) in a wide of range of applications in the field of environmental monitoring, including space.

Dr. Emiliano Zampetti
Dr. Fabrizio Dirri
Guest Editors

Manuscript Submission Information

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Keywords

Chemical sensors
Physical sensors
Chemical sensor array
Electronic nose
Smart sensors
Sensor networks
Wireless sensors
Chemical and physical sensors for space applications
Materials for chemical sensors
Quartz crystal microbalance for environmental monitoring
Surface acoustic wave sensor for environmental monitoring

Published Papers (6 papers)

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Research

Open AccessArticle

A New Mixed-Gas-Detection Method Based on a Support Vector Machine Optimized by a Sparrow Search Algorithm

Haitao Zhang

and

Yaozhen Han

Sensors 2022, 22(22), 8977; https://doi.org/10.3390/s22228977 - 20 Nov 2022

Viewed by 523

Abstract

To solve the problem of the low recognition rate of mixed gases and consider the phenomenon of low prediction accuracy when traditional gas-concentration-prediction methods deal with nonlinear data, this paper proposes a mixed-gas identification and gas-concentration-prediction method based on a support vector machine (SVM) optimized by a sparrow search algorithm (SSA). Principal component analysis (PCA) is applied to perform data dimensionality reduction on the input data, and SSA is adopted to optimize the SVM hyperparameters to improve the recognition rate and gas-concentration-prediction accuracy of mixed gases. For the mixed-gas identification, the classification accuracy is significantly improved under the proposed SSA optimization SVM method (SSA-SVM), compared with random forest (RF), extreme-learning machine (ELM), and BP neural network methods. With respect to gas-concentration prediction, the maximum fitting degrees reached 99.34% for single gas-concentration prediction and 97.55% for mixed-gas-concentration prediction. The experimental results show that the SSA-SVM method had a high recognition rate and high concentration-prediction accuracy in gas-mixture detection. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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Open AccessArticle

Naphthalene Detection in Air by Highly Sensitive TiO₂ Sensor: Real Time Response to Concentration Changes Monitored by Simultaneous UV Spectrophotometry

and

Sensors 2022, 22(19), 7272; https://doi.org/10.3390/s22197272 - 26 Sep 2022

Viewed by 724

Abstract

Volatile low-weight polycyclic aromatic hydrocarbons (PAHs) are known to be potentially toxic to humans and animals. Their detection in ambient air has been of great interest in recent years and various detection methods have been implemented. In this study, we used naphthalene as a basic model of such compounds and constructed our own version of a titanium oxide-based sensor system for its detection. The main goal of the study was to clearly demonstrate the effectiveness of this type of sensor, record its response under well-controlled conditions, and compare that response to concentration measurements made by the widely accepted spectrophotometric method. With that goal in mind, we recorded the sensor response while monitoring naphthalene vapor concentrations down to 95 nM as measured by spectrophotometry. Air flow over the sensor was passed continuously and sample measurements were made every 3 min for a period of up to 2 h. Over that period, several cycles of naphthalene contamination and cleaning were implemented and measurements were recorded. The relative humidity and temperature of the air being sampled were also monitored to assure no major variations occurred that could affect the measurements. The sensor showed high sensitivity and a reproducible response pattern to changes in naphthalene concentration. It could be easily “cleaned” of the compound in ten minutes by means of the application of UV light and the passing of fresh air. Pending testing with other volatile PAH, this type of sensor proves to be an effective and inexpensive way to detect naphthalene in air. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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Open AccessArticle

Classification of Three Volatiles Using a Single-Type eNose with Detailed Class-Map Visualization

Jordi Palacín

Elena Rubies

and

Eduard Clotet

Sensors 2022, 22(14), 5262; https://doi.org/10.3390/s22145262 - 14 Jul 2022

Cited by 3 | Viewed by 703

Abstract

The use of electronic noses (eNoses) as analysis tools are growing in popularity; however, the lack of a comprehensive, visual representation of how the different classes are organized and distributed largely complicates the interpretation of the classification results, thus reducing their practicality. The new contributions of this paper are the assessment of the multivariate classification performance of a custom, low-cost eNose composed of 16 single-type (identical) MOX gas sensors for the classification of three volatiles, along with a proposal to improve the visual interpretation of the classification results by means of generating a detailed 2D class-map representation based on the inverse of the orthogonal linear transformation obtained from a PCA and LDA analysis. The results showed that this single-type eNose implementation was able to perform multivariate classification, while the class-map visualization summarized the learned features and how these features may affect the performance of the classification, simplifying the interpretation and understanding of the eNose results. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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Open AccessCommunication

High-Frequency Vibration Analysis of Piezoelectric Array Sensor under Lateral-Field-Excitation Based on Crystals with 3 m Point Group

and

Sensors 2022, 22(9), 3596; https://doi.org/10.3390/s22093596 - 09 May 2022

Viewed by 909

Abstract

Based on Mindlin’s first-order plate theory, the high-frequency vibrations of piezoelectric bulk acoustic wave array sensors under lateral-field-excitation based on crystals with 3 m point group are analyzed, and the spectral-frequency relationships are solved, based on which, the optimal length–thickness ratio of the piezoelectric crystal plate is determined. Then, the dynamic capacitance diagram is obtained by a forced vibration analysis of the piezoelectric crystal plate. The resonant mode conforming to good energy trapping is further obtained. The frequency interferences between different resonator units are calculated, and the influences of the spacing between two resonant units on the frequency interference with different electrode widths and spacings are analyzed. Finally, the safe spacings between resonator units are obtained. As the electrode spacing value of the left unit increases, the safe spacing d₀ between the two resonator units decreases, and the frequency interference curve tends to zero faster. When the electrode spacings of two resonator units are equal, the safe distance is largest, and the frequency interference curve tends to zero slowest. The theoretical results are verified further by finite element method. The analysis model of high frequency vibrations of strongly coupled piezoelectric bulk acoustic array device based on LiTaO₃ crystals with 3 m point group proposed in this paper can provide reliable theoretical guidance for size optimization designs of strongly coupled piezoelectric array sensors under lateral-field-excitation. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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Open AccessArticle

Pocket Mercury-Vapour Detection System Employing a Preconcentrator Based on Au-TiO₂ Nanomaterials

and

Sensors 2021, 21(24), 8255; https://doi.org/10.3390/s21248255 - 10 Dec 2021

Cited by 2 | Viewed by 1464

Abstract

In environments polluted by mercury vapors that are potentially harmful to human health, there is a need to perform rapid surveys in order to promptly identify the sources of emission. With this aim, in this work, a low cost, pocket-sized portable mercury measurement system, with a fast response signal is presented. It consists of a preconcentrator, able to adsorb and subsequently release the mercury vapour detected by a quartz crystal microbalance (QCM) sensor. The preconcentrator is based on an adsorbing layer of titania/gold nanoparticles (TiO₂NP/AuNPs), deposited on a micro-heater that acts as mercury thermal desorption. For the detection of the released mercury vapour, gold electrodes QCM (20 MHz) have been used. The experimental results, performed in simulated polluted mercury-vapour environments, showed a detection capability with a prompt response. In particular, frequency shifts (−118 Hz ± 2 Hz and −30 Hz ± 2 Hz) were detected at concentrations of 65 µg/m³ Hg⁰ and 30 µg/m³ Hg⁰, with sampling times of 60 min and 30 min, respectively. A system limit of detection (LOD) of 5 µg/m³ was evaluated for the 30 min sampling time. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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Open AccessArticle

A Multi-Sensor System for Sea Water Iodide Monitoring and Seafood Quality Assurance: Proof-of-Concept Study

and

Sensors 2021, 21(13), 4464; https://doi.org/10.3390/s21134464 - 29 Jun 2021

Cited by 2 | Viewed by 1305

Abstract

Iodine is a trace chemical element fundamental for a healthy human organism. Iodine deficiency affects about 2 billion people worldwide causing from mild to severe neurological impairment, especially in children. Nevertheless, an adequate nutritional intake is considered the best approach to prevent such disorders. Iodine is present in seawater and seafood, and its common forms in the diet are iodide and iodate; most iodide in seawater is caused by the biological reduction of the thermodynamically stable iodate species. On this basis, a multisensor instrument which is able to perform a multidimensional assessment, evaluating iodide content in seawater and seafood (via an electrochemical sensor) and discriminating when the seafood is fresh or defrosted quality (via a Quartz Micro balance (QMB)-based volatile and gas sensor), is strategic for seafood quality assurance. Moreover, an electronic interface has been opportunely designed and simulated for a low-power portable release of the device, which should be able to identify seafood over or under an iodide threshold previously selected. The electrochemical sensor has been successfully calibrated in the range 10–640 μg/L, obtaining a root mean square error in cross validation (RMSECV) of only 1.6 μg/L. Fresh and defrosted samples of cod, sea bream and blue whiting fish have been correctly discriminated. This proof-of-concept work has demonstrated the feasibility of the proposed application which must be replicated in a real scenario. Full article

(This article belongs to the Special Issue Electronic Gas Sensors, Sensor Arrays, and Electronic Noses for Indoor and Outdoor Environment Monitoring)

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