Due to planned maintenance work on our platforms, there might be short service disruptions on Saturday, December 3rd, between 15:00 and 16:00 (CET).

Topical Collection "Recent Advances in Multifunctional Sensing Technology for Gas Analysis"

A topical collection in Chemosensors (ISSN 2227-9040). This collection belongs to the section "Applied Chemical Sensors".

Editor

Dr. Simonetta Capone
E-Mail Website
Collection Editor
Institute for Microelectronics and Microsystems, National Research Council, CNR-IMM, Via Monteroni, Campus Ecotekne, 73100 Lecce, Italy
Interests: gas sensors; electronic noses; chemical analytical methods by SPME/GC-MS; multifunctional sensor systems for gas analysis; chemical sensing devices with low power sensor interface

Topical Collection Information

Dear Colleagues,

This Topical Collection is addressed to the main advances and new directions in gas-sensing devices aiming to collect the most relevant works concerning such challenging topic. Gas Sensors and Multifunctional Gas Sensing Systems that are expected to improve the quality of human life by applying them to achieve specific purposes in various areas of daily life.

Stimulated by the multiple applications of gas sensors, research in this field is constantly evolving, based on advances in the synthesis and deposition of new gas-sensitive nanomaterials. Moreover, innovative technological solutions offered by micro and nanotechnology provide novel functional microfabricated platforms for sensors arrays and the integration of sensing elements. Such advances open up opportunities for the development of a wide range of gas-sensing devices based on different sensing principles and with improved properties (high detectivity, specificity, low power consumption, multifunctionality, and miniaturized size).

Major interests driving the gas sensors market across the world are environment monitoring, air quality analysis, food industry, industrial processing, automotive and aerospace industries, healthcare, breath analysis and volatilomics as early diagnostics in medicine and human biomonitoring. A large growth of the gas sensors market in the coming years will result from IoT applications, such as smart cities, smart homes, smartphones, and wearable devices.

This Topical Collection of the journal Chemosensors aims to cover various aspects of gas sensors and their applications, such as (but not limited to) the preparation/deposition/characterization of gas-sensing materials, the development of MEMS/NEMS platforms for the integration of gas sensing and nanomaterials, gas-sensing principles, electronic noses, analytical chemistry methods, electronic interfaces for chemical sensors, the development of devices for actual applications.

We invite all researchers working on gas sensors to submit their original research studies to this Topical Collection. Both review articles and original research papers are welcomed.

Potential topics include but are not limited to:

  • Nanomaterials with gas-sensing properties
  • Low-dimensional nanostructures
  • Gas-sensing principles
  • Micro/nano-fabrication
  • Sensor array development
  • Electronic noses
  • Electronics for chemical device
  • Data analysis and pattern recognition
  • Applications

Dr. Simonetta Capone
Collection Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Chemosensors is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (17 papers)

2022

Jump to: 2021

Article
Nanostructured Diamond Composites for Multifunctional Sensing Applications
Chemosensors 2022, 10(11), 488; https://doi.org/10.3390/chemosensors10110488 - 17 Nov 2022
Viewed by 310
Abstract
We report studies of multifunctional, nanostructured diamond composites that were fabricated using chemical vapor deposition (CVD) techniques. Grain sizes from micrometer, to submicron, nano, and ultrananocrystalline diamond (UNCD) were controlled by varying CH4, hydrogen, and argon gas concentrations during the syntheses. [...] Read more.
We report studies of multifunctional, nanostructured diamond composites that were fabricated using chemical vapor deposition (CVD) techniques. Grain sizes from micrometer, to submicron, nano, and ultrananocrystalline diamond (UNCD) were controlled by varying CH4, hydrogen, and argon gas concentrations during the syntheses. Scanning electron microscopy (SEM) and Raman scattering spectroscopy were used to investigate the morphologies, composites, and crystallinities of the films. Four multifunctional sensor prototypes were designed, fabricated, and tested, based on the four diamond materials of different grain sizes. The responses of the four prototypes to either pollution gas or UV light illumination were systematically investigated at different operating temperatures. Experimental data indicated the obtained UNCD composite from the low-cost simple CVD fabrication technique appeared to have very good sensitivities when exposed to low concentrations of H2 or NH3 gas with a decent response and fast recovery time. Furthermore, highly induced photocurrents from both microdiamond- and UNCD-based prototypes to deep UV illumination were also demonstrated, with responsivities up to 2750 mA/W and 550 mA/W at 250 nm wavelength, respectively. Overall, the fabricated UNCD prototypes displayed a good balance in performance for multifunctional sensor applications in terms of responsivity, stability, and repeatability. Full article
Show Figures

Figure 1

Article
Enhanced Gas Detection by Altering Gate Voltage Polarity of Polypyrrole/Graphene Field-Effect Transistor Sensor
Chemosensors 2022, 10(11), 467; https://doi.org/10.3390/chemosensors10110467 - 09 Nov 2022
Viewed by 413
Abstract
This work introduces a new measurement methodology for enhancing gas detection by tuning the magnitude and polarity of back-gate voltage of a field-effect transistor (FET)-based sensor. The aim is to simultaneously strengthen the sensor response and accelerate the sensor recovery. In addition, this [...] Read more.
This work introduces a new measurement methodology for enhancing gas detection by tuning the magnitude and polarity of back-gate voltage of a field-effect transistor (FET)-based sensor. The aim is to simultaneously strengthen the sensor response and accelerate the sensor recovery. In addition, this methodology can consume less energy compared with conventional measurements by direct current bias. To illustrate the benefits of the proposed methodology, we fabricated and characterized a polypyrrole/graphene (PPy/G) FET sensor for ammonia (NH3) detection. Our experiment, simulation and calculation results demonstrated that the redox reaction between the NH3 molecules and the PPy/G sensitive layer could be controlled by altering the polarity and the magnitude of the back-gate voltage. This proof-of-principle measurement methodology, which solves the inherent contradiction between high response and slow recovery of the chemiresistive sensor, could be extended to detect other gases, so as to improve global gas measurement systems. It opens up a new route for FET-based gas sensors in practical applications. Full article
Show Figures

Figure 1

Article
Application of a Single-Type eNose to Discriminate the Brewed Aroma of One Caffeinated and Decaffeinated Encapsulated Espresso Coffee Type
Chemosensors 2022, 10(10), 421; https://doi.org/10.3390/chemosensors10100421 - 13 Oct 2022
Viewed by 509
Abstract
This paper assesses a custom single-type electronic nose (eNose) applied to differentiate the complex aromas generated by the caffeinated and decaffeinated versions of one encapsulated espresso coffee mixture type. The eNose used is composed of 16 single-type (identical) metal–oxide semiconductor (MOX) gas sensors [...] Read more.
This paper assesses a custom single-type electronic nose (eNose) applied to differentiate the complex aromas generated by the caffeinated and decaffeinated versions of one encapsulated espresso coffee mixture type. The eNose used is composed of 16 single-type (identical) metal–oxide semiconductor (MOX) gas sensors based on microelectromechanical system (MEMS). This eNose proposal takes advantage of the small but inherent sensing variability of MOX gas sensors in order to provide a multisensorial description of volatiles or aromas. Results have shown that the information provided with this eNose processed using LDA is able to successfully discriminate the complex aromas of one caffeinated and decaffeinated encapsulated espresso coffee type. Full article
Show Figures

Figure 1

Article
Au-Decorated Polyaniline-ZnO Electrospun Composite Nanofiber Gas Sensors with Enhanced Response to NO2 Gas
Chemosensors 2022, 10(10), 388; https://doi.org/10.3390/chemosensors10100388 - 24 Sep 2022
Viewed by 591
Abstract
Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of [...] Read more.
Ternary systems are less studied for sensing applications due to complex synthesis procedures. However, they have more sources of resistance modulation, leading to an enhanced gas response. In this study, a ternary system, namely Au-decorated ZnO-polyaniline (PANI) composite nanofibers with different amounts of PANI (10, 25, and 50 wt.%) were synthesized for NO2 gas sensing studies. First, ZnO nanofibers were synthesized by electrospinning, and then an Au layer (9 nm) was coated on the ZnO nanofibers. Finally, PANI was coated onto the prepared Au-decorated ZnO nanofibers. NO2 gas sensing investigations indicated that the sensor with 25 wt.% PANI had the best response to NO2 gas at 300 °C. In addition, the optimized sensor exhibited high selectivity to NO2 gas. The improved performance of the optimal gas sensor was attributed to the role of Au, the formation of ZnO-PANI heterojunctions, and the optimal amount of PANI. The promising effect of this ternary system for NO2 sensing was demonstrated, and it can be extended to other similar systems. Full article
Show Figures

Figure 1

Article
Spinel Magnesium Ferrite (MgFe2O4): A Glycine-Assisted Colloidal Combustion and Its Potentiality in Gas-Sensing Application
Chemosensors 2022, 10(9), 361; https://doi.org/10.3390/chemosensors10090361 - 09 Sep 2022
Cited by 1 | Viewed by 618
Abstract
Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas sensor using a straightforward and reliable sol–gel approach, i.e., the glycine-assisted auto-combustion route. The novelty in obtaining the sensing material via the auto-combustion [...] Read more.
Herein, we describe the facile synthesis of spinel MgFe2O4 ferrite and its potential use as a gas sensor using a straightforward and reliable sol–gel approach, i.e., the glycine-assisted auto-combustion route. The novelty in obtaining the sensing material via the auto-combustion route is its inherent simplicity and capability to produce the material at an industry scale. The said cost-effective process makes use of simple metal salts (Mg and Fe-nitrates) and glycine in an aqueous solution, which leads to the formation of spinel MgFe2O4 ferrite. A single-phase crystallinity with crystallite sizes ranging between 36 and 41 nm was observed for the synthesized materials using the X-ray diffraction (XRD) technique. The porous morphologies of the synthesized materials caused by auto-ignition during the combustion process were validated by the microscopic investigations. The EDS analysis confirmed the constituted elements such as Mg, Fe, and O, without any impurity peaks. The gas-sensing ability of the synthesized ferrites was examined to detect various reducing gases such as LPG, ethanol, acetone, and ammonia. The ferrite showed the highest response (>80%) toward LPG with the response and recovery times of 15 s and 23 s, respectively. Though the sensor responded low toward ammonia (~30%), its response and recovery times were very quick, i.e., 7 s and 9 s, respectively. The present investigation revealed that the synthesized ferrite materials are good candidates for fabricating high-performance sensors for reducing gases in real-world applications. Full article
Show Figures

Figure 1

Article
Effects of Calcination Temperature on CO-Sensing Mechanism for NiO-Based Gas Sensors
Chemosensors 2022, 10(5), 191; https://doi.org/10.3390/chemosensors10050191 - 19 May 2022
Cited by 1 | Viewed by 1015
Abstract
NiO-sensitive materials have been synthesized via the hydrothermal synthesis route and calcined in air at 400 °C and, alternatively, at 500 °C. Structural, morphological, and spectroscopic investigations were involved. As such, the XRD patterns showed a higher crystallinity degree for the NiO calcined [...] Read more.
NiO-sensitive materials have been synthesized via the hydrothermal synthesis route and calcined in air at 400 °C and, alternatively, at 500 °C. Structural, morphological, and spectroscopic investigations were involved. As such, the XRD patterns showed a higher crystallinity degree for the NiO calcined at 500 °C. Such an aspect is in line with the XPS data indicating a lower surface hydroxylation relative to NiO calcined at 400 °C. An HRTEM microstructural investigation revealed that the two samples differ essentially at the morphological level, having different sizes of the crystalline nanoparticles, different density of the surface defects, and preferential faceting according to the main crystallographic planes. In order to identify their specific gas-sensing mechanism towards CO exposure under the in-field atmosphere, the simultaneous evaluation of the electrical resistance and contact potential difference was carried out. The results allowed the decoupling of the water physisorption from the chemisorption of the ambient oxygen species. Thus, the specific CO interaction mechanism induced by the calcination temperature of NiO has been highlighted. Full article
Show Figures

Figure 1

Communication
Comparative Analysis of Derivative Parameters of Chemoresistive Sensor Signals for Gas Concentration Estimation
Chemosensors 2022, 10(4), 126; https://doi.org/10.3390/chemosensors10040126 - 29 Mar 2022
Viewed by 1263
Abstract
Signals from resistive gas sensors based on zirconium dioxide and silicon–carbon films have been extensively investigated to estimate gas concentration. In this study, the change in the normalized resistance of the sensor’s response under NO2 exposure is shown and the analysis of [...] Read more.
Signals from resistive gas sensors based on zirconium dioxide and silicon–carbon films have been extensively investigated to estimate gas concentration. In this study, the change in the normalized resistance of the sensor’s response under NO2 exposure is shown and the analysis of the first and second derivatives of the response curves were carried out. A signal-processing scheme, reducing the effect of noise and signal drift, is proposed. The extreme of the second derivative of the sensor response, the initial reaction rate, and the slope of the curve of the approximating line in the coordinates of the Elovich equation are proposed as calibration dependencies. The calibration curves built from the values of the maximum second derivative turned out to be the most stable, with the lowest relative error in estimating gas concentration compared to the traditional fixed-time point method. Full article
Show Figures

Figure 1

2021

Jump to: 2022

Article
Silicon MEMS Thermocatalytic Gas Sensor in Miniature Surface Mounted Device Form
Chemosensors 2021, 9(12), 340; https://doi.org/10.3390/chemosensors9120340 - 03 Dec 2021
Cited by 2 | Viewed by 1504
Abstract
A reduced size thermocatalytic gas sensor was developed for the detection of methane over the 20% of the explosive concentration. The sensor chip is formed from two membranes with a 150 µm diameter heated area in their centers and covered with highly dispersed [...] Read more.
A reduced size thermocatalytic gas sensor was developed for the detection of methane over the 20% of the explosive concentration. The sensor chip is formed from two membranes with a 150 µm diameter heated area in their centers and covered with highly dispersed nano-sized catalyst and inert reference, respectively. The power dissipation of the chip is well below 70 mW at the 530 °C maximum operation temperature. The chip is mounted in a novel surface mounted metal-ceramic sensor package in the form-factor of SOT-89. The sensitivity of the device is 10 mV/v%, whereas the response and recovery times without the additional carbon filter over the chip are <500 ms and <2 s, respectively. The tests have shown the reliability of the new design concerning the hotplate stability and massive encapsulation, but the high degradation rate of the catalyst coupled with its modest chemical power limits the use of the sensor only in pulsed mode of operation. The optimized pulsed mode reduces the average power consumption below 2 mW. Full article
Show Figures

Figure 1

Article
Performance Analysis of MAU-9 Electronic-Nose MOS Sensor Array Components and ANN Classification Methods for Discrimination of Herb and Fruit Essential Oils
Chemosensors 2021, 9(9), 243; https://doi.org/10.3390/chemosensors9090243 - 31 Aug 2021
Cited by 18 | Viewed by 1911
Abstract
The recent development of MAU-9 electronic sensory methods, based on artificial olfaction detection of volatile emissions using an experimental metal oxide semiconductor (MOS)-type electronic-nose (e-nose) device, have provided novel means for the effective discovery of adulterated and counterfeit essential oil-based plant products sold [...] Read more.
The recent development of MAU-9 electronic sensory methods, based on artificial olfaction detection of volatile emissions using an experimental metal oxide semiconductor (MOS)-type electronic-nose (e-nose) device, have provided novel means for the effective discovery of adulterated and counterfeit essential oil-based plant products sold in worldwide commercial markets. These new methods have the potential of facilitating enforcement of regulatory quality assurance (QA) for authentication of plant product genuineness and quality through rapid evaluation by volatile (aroma) emissions. The MAU-9 e-nose system was further evaluated using performance-analysis methods to determine ways for improving on overall system operation and effectiveness in discriminating and classifying volatile essential oils derived from fruit and herbal edible plants. Individual MOS-sensor components in the e-nose sensor array were performance tested for their effectiveness in contributing to discriminations of volatile organic compounds (VOCs) analyzed in headspace from purified essential oils using artificial neural network (ANN) classification. Two additional statistical data-analysis methods, including principal regression (PR) and partial least squares (PLS), were also compared. All statistical methods tested effectively classified essential oils with high accuracy. Aroma classification with PLS method using 2 optimal MOS sensors yielded much higher accuracy than using all nine sensors. The accuracy of 2-group and 6-group classifications of essentials oils by ANN was 100% and 98.9%, respectively. Full article
Show Figures

Figure 1

Article
Selective Determination of Hydrogen Sulfide Using SnO2–Ag Sensor Working in Non-Stationary Temperature Regime
Chemosensors 2021, 9(8), 203; https://doi.org/10.3390/chemosensors9080203 - 02 Aug 2021
Cited by 3 | Viewed by 1468
Abstract
The application of a non-stationary regime of temperature modulation in metal oxide semiconductor sensor based on SnO2–Ag leads not only to a strongly increased sensor response, but also to a considerably improved sensor selectivity toward hydrogen sulfide. Selectivity with respect to [...] Read more.
The application of a non-stationary regime of temperature modulation in metal oxide semiconductor sensor based on SnO2–Ag leads not only to a strongly increased sensor response, but also to a considerably improved sensor selectivity toward hydrogen sulfide. Selectivity with respect to other reducing gases (CO, NH3, H2) is about five orders of magnitude, enabling a correct selective determination of H2S in the presence of interfering gas components. Full article
Show Figures

Graphical abstract

Article
Ionogels Based on a Single Ionic Liquid for Electronic Nose Application
Chemosensors 2021, 9(8), 201; https://doi.org/10.3390/chemosensors9080201 - 30 Jul 2021
Cited by 2 | Viewed by 1706
Abstract
Ionogel are versatile materials, as they present the electrical properties of ionic liquids and also dimensional stability, since they are trapped in a solid matrix, allowing application in electronic devices such as gas sensors and electronic noses. In this work, ionogels were designed [...] Read more.
Ionogel are versatile materials, as they present the electrical properties of ionic liquids and also dimensional stability, since they are trapped in a solid matrix, allowing application in electronic devices such as gas sensors and electronic noses. In this work, ionogels were designed to act as a sensitive layer for the detection of volatiles in a custom-made electronic nose. Ionogels composed of gelatin and a single imidazolium ionic liquid were doped with bare and functionalized iron oxide nanoparticles, producing ionogels with adjustable target selectivity. After exposing an array of four ionogels to 12 distinct volatile organic compounds, the collected signals were analyzed by principal component analysis (PCA) and by several supervised classification methods, in order to assess the ability of the electronic nose to distinguish different volatiles, which showed accuracy above 98%. Full article
Show Figures

Graphical abstract

Review
One-Dimensional Nanomaterials in Resistive Gas Sensor: From Material Design to Application
Chemosensors 2021, 9(8), 198; https://doi.org/10.3390/chemosensors9080198 - 30 Jul 2021
Cited by 14 | Viewed by 3131
Abstract
With a series of widespread applications, resistive gas sensors are considered to be promising candidates for gas detection, benefiting from their small size, ease-of-fabrication, low power consumption and outstanding maintenance properties. One-dimensional (1-D) nanomaterials, which have large specific surface areas, abundant exposed active [...] Read more.
With a series of widespread applications, resistive gas sensors are considered to be promising candidates for gas detection, benefiting from their small size, ease-of-fabrication, low power consumption and outstanding maintenance properties. One-dimensional (1-D) nanomaterials, which have large specific surface areas, abundant exposed active sites and high length-to-diameter ratios, enable fast charge transfers and gas-sensitive reactions. They can also significantly enhance the sensitivity and response speed of resistive gas sensors. The features and sensing mechanism of current resistive gas sensors and the potential advantages of 1-D nanomaterials in resistive gas sensors are firstly reviewed. This review systematically summarizes the design and optimization strategies of 1-D nanomaterials for high-performance resistive gas sensors, including doping, heterostructures and composites. Based on the monitoring requirements of various characteristic gases, the available applications of this type of gas sensors are also classified and reviewed in the three categories of environment, safety and health. The direction and priorities for the future development of resistive gas sensors are laid out. Full article
Show Figures

Figure 1

Article
The UV Effect on the Chemiresistive Response of ZnO Nanostructures to Isopropanol and Benzene at PPM Concentrations in Mixture with Dry and Wet Air
Chemosensors 2021, 9(7), 181; https://doi.org/10.3390/chemosensors9070181 - 14 Jul 2021
Cited by 3 | Viewed by 2139
Abstract
Towards the development of low-power miniature gas detectors, there is a high interest in the research of light-activated metal oxide gas sensors capable to operate at room temperature (RT). Herein, we study ZnO nanostructures grown by the electrochemical deposition method over Si/SiO2 [...] Read more.
Towards the development of low-power miniature gas detectors, there is a high interest in the research of light-activated metal oxide gas sensors capable to operate at room temperature (RT). Herein, we study ZnO nanostructures grown by the electrochemical deposition method over Si/SiO2 substrates equipped by multiple Pt electrodes to serve as on-chip gas monitors and thoroughly estimate its chemiresistive performance upon exposing to two model VOCs, isopropanol and benzene, in a wide operating temperature range, from RT to 350 °C, and LED-powered UV illumination, 380 nm wavelength; the dry air and humid-enriched, 50 rel. %, air are employed as a background. We show that the UV activation allows one to get a distinctive chemiresistive signal of the ZnO sensor to isopropanol at RT regardless of the interfering presence of H2O vapors. On the contrary, the benzene vapors do not react with UV-illuminated ZnO at RT under dry air while the humidity’s appearance gives an opportunity to detect this gas. Still, both VOCs are well detected by the ZnO sensor under heating at a 200–350 °C range independently on additional UV exciting. We employ quantum chemical calculations to explain the differences between these two VOCs’ interactions with ZnO surface by a remarkable distinction of the binding energies characterizing single molecules, which is −0.44 eV in the case of isopropanol and −3.67 eV in the case of benzene. The full covering of a ZnO supercell by H2O molecules taken for the effect’s estimation shifts the binding energies to −0.50 eV and −0.72 eV, respectively. This theory insight supports the experimental observation that benzene could not react with ZnO surface at RT under employed LED UV without humidity’s presence, indifference to isopropanol. Full article
Show Figures

Graphical abstract

Review
Strategies for Improving the Sensing Performance of Semiconductor Gas Sensors for High-Performance Formaldehyde Detection: A Review
Chemosensors 2021, 9(7), 179; https://doi.org/10.3390/chemosensors9070179 - 14 Jul 2021
Cited by 9 | Viewed by 3012
Abstract
Formaldehyde is a poisonous and harmful gas, which is ubiquitous in our daily life. Long-term exposure to formaldehyde harms human body functions; therefore, it is urgent to fabricate sensors for the real-time monitoring of formaldehyde concentrations. Metal oxide semiconductor (MOS) gas sensors is [...] Read more.
Formaldehyde is a poisonous and harmful gas, which is ubiquitous in our daily life. Long-term exposure to formaldehyde harms human body functions; therefore, it is urgent to fabricate sensors for the real-time monitoring of formaldehyde concentrations. Metal oxide semiconductor (MOS) gas sensors is favored by researchers as a result of their low cost, simple operation and portability. In this paper, the mechanism of formaldehyde detection by gas sensors is introduced, and then the ways of ameliorating the response of gas sensors for formaldehyde detection in recent years are summarized. These methods include the control of the microstructure and morphology of sensing materials, the doping modification of matrix materials, the development of new semiconductor sensing materials, the outfield control strategy and the construction of the filter membrane. These five methods will provide a good prerequisite for the preparation of better performing formaldehyde gas sensors. Full article
Show Figures

Figure 1

Article
A Gas Sensor Based on Network Nanowire for H2S Monitor in Construction Waste Landfill
Chemosensors 2021, 9(7), 156; https://doi.org/10.3390/chemosensors9070156 - 25 Jun 2021
Viewed by 994
Abstract
As an extremely harmful gas, H2S gas is the major pollutant in construction waste landfill. Herein, a one-dimensional oxide nanomaterial was produced from a simple wet chemical method to serve as a H2S gas sensing material. The SEM observation [...] Read more.
As an extremely harmful gas, H2S gas is the major pollutant in construction waste landfill. Herein, a one-dimensional oxide nanomaterial was produced from a simple wet chemical method to serve as a H2S gas sensing material. The SEM observation indicates that the nanomaterial with network structure is constructed by a lot of nanowires with an approximate diameter from 24 nm to 40 nm. The sensing film was formed on a ceramic substrate using a slurry composed of the as-prepared network nanowires. Furthermore, a gas sensing measurement was carried out to determine the gas sensing performances towards the H2S gas. The detection results at different working temperature towards various gas concentrations demonstrate that the network nanowires-based sensor exhibits a higher gas response to H2S as compared to that of the rod-like one. The optimum working temperature of the network and rod-like nanomaterials is both 300 °C, and the corresponding maximum gas response is 24.4 and 13.6, respectively. Namely, the gas response of the network-based gas sensor is almost larger than that of the rod-like oxide. Moreover, the network nanowires-based gas sensor display a faster gas response and recovery speed. In addition, the fabricated gas sensors all exhibit excellent repeatability. Such improved sensing properties may offer a promising potential to realize an efficient detection of harmful H2S gas released from construction waste landfill. Full article
Show Figures

Figure 1

Article
Classification and Identification of Essential Oils from Herbs and Fruits Based on a MOS Electronic-Nose Technology
Chemosensors 2021, 9(6), 142; https://doi.org/10.3390/chemosensors9060142 - 16 Jun 2021
Cited by 28 | Viewed by 2420
Abstract
The frequent occurrence of adulterated or counterfeit plant products sold in worldwide commercial markets has created the necessity to validate the authenticity of natural plant-derived palatable products, based on product-label composition, to certify pricing values and for regulatory quality control (QC). The necessity [...] Read more.
The frequent occurrence of adulterated or counterfeit plant products sold in worldwide commercial markets has created the necessity to validate the authenticity of natural plant-derived palatable products, based on product-label composition, to certify pricing values and for regulatory quality control (QC). The necessity to confirm product authenticity before marketing has required the need for rapid-sensing, electronic devices capable of quickly evaluating plant product quality by easily measurable volatile (aroma) emissions. An experimental MAU-9 electronic nose (e-nose) system, containing a sensor array with 9 metal oxide semiconductor (MOS) gas sensors, was developed with capabilities to quickly identify and classify volatile essential oils derived from fruit and herbal edible-plant sources. The e-nose instrument was tested for efficacy to discriminate between different volatile essential oils present in gaseous emissions from purified sources of these natural food products. Several chemometric data-analysis methods, including pattern recognition algorithms, principal component analysis (PCA), and support vector machine (SVM) were utilized and compared. The classification accuracy of essential oils using PCA, LDA and QDA, and SVM methods was at or near 100%. The MAU-9 e-nose effectively distinguished between different purified essential oil aromas from herbal and fruit plant sources, based on unique e-nose sensor array responses to distinct, essential-oil specific mixtures of volatile organic compounds (VOCs). Full article
Show Figures

Figure 1

Article
A Hairpin DNA-Based Piezoelectric E-Nose: Exploring the Performances of Heptamer Loops for the Detection of Volatile Organic Compounds
Chemosensors 2021, 9(5), 115; https://doi.org/10.3390/chemosensors9050115 - 20 May 2021
Cited by 1 | Viewed by 1259
Abstract
A hairpin DNA (hpDNA) piezoelectric gas sensors array with heptamer loops as sensing elements was designed, realized, and challenged with pure volatile organic compounds VOCs and real samples (beer). The virtual binding versus five chemical classes (alcohols, aldehydes, esters, hydrocarbons, and ketones) of [...] Read more.
A hairpin DNA (hpDNA) piezoelectric gas sensors array with heptamer loops as sensing elements was designed, realized, and challenged with pure volatile organic compounds VOCs and real samples (beer). The virtual binding versus five chemical classes (alcohols, aldehydes, esters, hydrocarbons, and ketones) of the entire combinatorial library of heptamer loops (16,384 elements) was studied by molecular modelling. Six heptamer loops, having the largest variance in binding the chemical classes, were selected to build the array. The six gas sensors were realized by immobilizing onto gold nanoparticles (AuNPs) via a thiol spacer the hpDNA constituted by the heptamer loops and the same double helix stem of four base pairs (GAAG at 5′ and CTTC at 3′ end). The HpDNA-AuNP was used to modify the surface of 20 MHz quartz crystal microbalances (QCMs). The realized E-nose was able to clearly discriminate among 15 pure VOCs of different chemical classes, as demonstrated by hierarchical cluster analysis. The analysis of real beer samples during fermentation was also carried out. In such a challenging matrix consisting of 23 different VOCs, the hpDNA E-nose with heptamer loops was able to discriminate among different fermentation times with high success rate. Class assignment using the Bayes theorem gave an excellent 98% correct beer samples classification in cross-validation. Full article
Show Figures

Figure 1

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: A review of paper based chemiresistive sensor for gas and ion detection
Authors: Philip Nathaniel Immanuel; Song-Jeng Huang; Yudhistira Adityawardhana; Yi-Kuang Yen
Affiliation: 1 Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan. 2 Department of Mechanical Engineering, National Taipei University of Technology, Taipei 106, Taiwan.
Abstract: Chemiresistive gas and ion sensors have been widely utilized to detect analytes of great significance to the environment, food and health. Paper based sensor which can be constructed on a low-cost paper substrate a simple and cost-efficient fabrication process attracts many interests to develop. Moreover, many materials that can be employed for designing chemiresistive sensors, such as carbon based nanomaterials, conductive polymers, metal oxides and inorganic chemical compounds. Most of them can provide large surface area and pitted structure, along with extraordinary electrical and thermal conductivities which are capable to improve sensor performance regarding sensitivity, selectivity and stability. In this review, we survey recent advances on different types of paper based chemiresistive gas and ion sensors, focusing on how the physical and chemical properties of these materials influence on the sensor response. Challenges and future perspectives for paper based chemiresistive sensors are also discussed.

Back to TopTop