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Chemical Sensors and Sensor Systems for the Detection and Separation of Volatile Organic Compounds

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

Deadline for manuscript submissions: closed (31 July 2020) | Viewed by 20476

Special Issue Editor


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Guest Editor
School of Engineering, University of Warwick, Coventry CV4 7AL, UK
Interests: electronic noses; machine olfaction; chemical sensors; MEMS; smart sensor systems; data analysis; deep learning; neural networks; industrial applications and medical applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

There has been an exponential rise in the use of chemical and gas sensors for a broad spectrum of applications from environmental monitoring and indoor air quality to safety application and even breath analysis for disease diagnosis. However, all of these application are limited by the current state-of-the-art sensor approaches for detecting and identifying volatile organic compounds (VOC). Though sensors for inorganic sensors, such as CO and NOx, are now commonplace, it is the detection and separation of VOCs in simple or complex mixtures remain a major challenge. This is particularly challenging for complex mixtures of VOCs that are orders of magnitude different in concentration, as needed in many environmental applications. VOC separation is possible with high-end analytical platforms, such as mass-spectrometry, however such solutions unrealistic for long-term monitoring or portable/IOT devices that need to separate and detect VOCs.

This Special Issue of Sensors will be dedicated to highlighting the sensors, micro-systems and technologies for the separation and identification of VOCs – with particular emphasis of low-cost/miniaturised approaches. The sensors could use any form of physical or chemical route to detect and separate VOCs and can focus on the sensor materials, sensor system or the application. Full papers, communications and reviews are welcome. Topics include, but are not limited to, the following:

  • Nano-materials/2D materials, such as carbon nanomaterials (nanowires, nanorods, nanotubes, nanobelts, nanoribbons, nanofibers, hierarchical nanostructures and their hybrids).
  • Gas sensing properties of Three-dimensional, such as metal organic-frameworks (MOFs), molecularly imprinted polymers (MIPs) with nanoballs, nanocoils, nanocones, nanopillars or nanoflowers-like morphologies.
  • Chemoresistive sensors as using metal-oxide sensors, or conductometric, electrochemical, resonant or optical gas sensors for VOC detection.
  • Sensor arrays, distributed sensors and MEMS/micro-based based sensor solutions.
  • Microsystem solutions, including microGCs, pre-concentrators, ion mobility and portable mass-spectrometry solutions.
  • Applications for gas sensors, including outdoor/indoor environmental monitoring, security, safety and medical.

The purpose of the Special Issue is to collect original research papers or review articles. Although the emphasis is on practical solutions, we also welcome fundamental studies in the detection and separation of VOCs.

Prof. Dr. James Covington
Guest 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 special issue 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. Sensors is an international peer-reviewed open access semimonthly 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 2600 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.

Keywords

  • volatile organic compounds
  • chemical sensors
  • Gas sensors
  • Nanomaterials
  • Metal oxides
  • Electrochemical sensors
  • Optical Sensors
  • Polymer sensors
  • Pre-concentrators
  • MEMS gas sensors
  • Chemical Micro-systems
  • VOC applications

Published Papers (4 papers)

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Research

12 pages, 3350 KiB  
Article
Assessment of Electronic Sensing Techniques for the Rapid Identification of Alveolar Echinococcosis through Exhaled Breath Analysis
by Andrzej Kwiatkowski, Tomasz Chludziński, Tarik Saidi, Tesfalem Geremariam Welearegay, Aylen Lisset Jaimes-Mogollón, Nezha El Bari, Sebastian Borys, Benachir Bouchikhi, Janusz Smulko and Radu Ionescu
Sensors 2020, 20(9), 2666; https://doi.org/10.3390/s20092666 - 07 May 2020
Cited by 5 | Viewed by 2717
Abstract
Here we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas [...] Read more.
Here we present a proof-of-concept study showing the potential of a chemical gas sensors system to identify the patients with alveolar echinococcosis disease through exhaled breath analysis. The sensors system employed comprised an array of three commercial gas sensors and a custom gas sensor based on WO3 nanowires doped with gold nanoparticles, optimized for the measurement of common breath volatile organic compounds. The measurement setup was designed for the concomitant measurement of both sensors DC resistance and AC fluctuations during breath samples exposure. Discriminant Function Analysis classification models were built with features extracted from sensors responses, and the discrimination of alveolar echinococcosis was estimated through bootstrap validation. The commercial sensor that detects gases such as alkane derivatives and ethanol, associated with lipid peroxidation and intestinal gut flora, provided the best classification (63.4% success rate, 66.3% sensitivity and 54.6% specificity) when sensors’ responses were individually analyzed, while the model built with the AC features extracted from the responses of the cross-reactive sensors array yielded 90.2% classification success rate, 93.6% sensitivity and 79.4% specificity. This result paves the way for the development of a noninvasive, easy to use, fast and inexpensive diagnostic test for alveolar echinococcosis diagnosis at an early stage, when curative treatment can be applied to the patients. Full article
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13 pages, 3789 KiB  
Article
Development of Open-Tubular-Type Micro Gas Chromatography Column with Bump Structures
by Janghyeon Lee and Si-Hyung Lim
Sensors 2019, 19(17), 3706; https://doi.org/10.3390/s19173706 - 26 Aug 2019
Cited by 7 | Viewed by 7360
Abstract
Gas chromatography (GC) is the chemical analysis technique most widely used to separate and identify gas components, and it has been extensively applied in various gas analysis fields such as non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring. Micro-electro-mechanical systems [...] Read more.
Gas chromatography (GC) is the chemical analysis technique most widely used to separate and identify gas components, and it has been extensively applied in various gas analysis fields such as non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring. Micro-electro-mechanical systems (MEMS)-based GC columns are essential for miniaturizing an integrated gas analysis system (Micro GC system). This study reports an open-tubular-type micro GC (μ-GC) column with internal bump structures (bump structure μ-GC column) that substantially increase the interaction between the gas mixture and a stationary phase. The developed bump structure μ-GC column, which was fabricated on a 2 cm × 2 cm μ-GC chip and coated with a non-polar stationary phase, is 1.5 m-long, 150 μm-wide, and 400 μm-deep. It has an internal microfluidic channel in which the bumps, which are 150 μm diameter half-circles, are alternatingly disposed to face each other on the surface of the microchannel. The fabricated bump structure μ-GC column yielded a height-equivalent-to-a-theoretical-plate (HETP) of 0.009 cm (11,110 plates/m) at an optimal carrier gas velocity of 17 cm/s. The mechanically robust bump structure μ-GC column proposed in this study achieved higher separation efficiency than a commercially available GC column and a typical μ-GC column with internal post structures classified as a semi-packed-type column. The experimental results demonstrate that the developed bump structure μ-GC column can separate a gas mixture completely, with excellent separation resolution for formaldehyde, benzene, toluene, ethylbenzene, and xylene mixture, under programmed operating temperatures. Full article
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24 pages, 7919 KiB  
Article
Sub-ppm Formaldehyde Detection by n-n TiO2@SnO2 Nanocomposites
by Abulkosim Nasriddinov, Marina Rumyantseva, Artem Marikutsa, Alexander Gaskov, Jae-Hyoung Lee, Jae-Hun Kim, Jin-Young Kim, Sang Sub Kim and Hyoun Woo Kim
Sensors 2019, 19(14), 3182; https://doi.org/10.3390/s19143182 - 19 Jul 2019
Cited by 32 | Viewed by 5633
Abstract
Formaldehyde (HCHO) is an important indicator of indoor air quality and one of the markers for detecting lung cancer. Both medical and air quality applications require the detection of formaldehyde in the sub-ppm range. Nanocomposites SnO2/TiO2 are promising candidates for [...] Read more.
Formaldehyde (HCHO) is an important indicator of indoor air quality and one of the markers for detecting lung cancer. Both medical and air quality applications require the detection of formaldehyde in the sub-ppm range. Nanocomposites SnO2/TiO2 are promising candidates for HCHO detection, both in dark conditions and under UV illumination. Nanocomposites TiO2@SnO2 were synthesized by ALD method using nanocrystalline SnO2 powder as a substrate for TiO2 layer growth. The microstructure and composition of the samples were characterized by ICP-MS, TEM, XRD and Raman spectroscopy methods. The active surface sites were investigated using FTIR and TPR-H2 methods. The mechanism of formaldehyde oxidation on the surface of semiconductor oxides was studied by in situ DRIFTS method. The sensor properties of nanocrystalline SnO2 and TiO2@SnO2 nanocomposites toward formaldehyde (0.06–0.6 ppm) were studied by in situ electrical conductivity measurements in dark conditions and under periodic UV illumination at 50–300 °C. Nanocomposites TiO2@SnO2 exhibit a higher sensor signal than SnO2 and a decrease in the optimal measurement temperature by 50 °C. This result is explained based on the model considering the formation of n-n heterocontact at the SnO2/TiO2 interface. UV illumination leads to a decrease in sensor response compared with that obtained in dark conditions because of the photodesorption of oxygen involved in the oxidation of formaldehyde. Full article
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15 pages, 3411 KiB  
Article
A Binder Jet Printed, Stainless Steel Preconcentrator as an In-Line Injector of Volatile Organic Compounds
by Xiaolu Huang, Tyler Bauder, Truong Do, Hawke Suen, Connor Boss, Patrick Kwon and Junghoon Yeom
Sensors 2019, 19(12), 2748; https://doi.org/10.3390/s19122748 - 19 Jun 2019
Cited by 13 | Viewed by 3725
Abstract
A conventional approach to making miniature or microscale gas chromatography (GC) components relies on silicon as a base material and MEMS fabrication as manufacturing processes. However, these devices often fail in medium-to-high temperature applications due to a lack of robust fluidic interconnects and [...] Read more.
A conventional approach to making miniature or microscale gas chromatography (GC) components relies on silicon as a base material and MEMS fabrication as manufacturing processes. However, these devices often fail in medium-to-high temperature applications due to a lack of robust fluidic interconnects and a high-yield bonding process. This paper explores the feasibility of using metal additive manufacturing (AM), which is also known as metal 3D printing, as an alternative platform to produce small-scale microfluidic devices that can operate at a temperature higher than that which polymers can withstand. Binder jet printing (BJP), one of the metal AM processes, was utilized to make stainless steel (SS) preconcentrators (PCs) with submillimeter internal features. PCs can increase the concentration of gaseous analytes or serve as an inline injector for GC or gas sensor applications. Normally, parts printed by BJP are highly porous and thus often infiltrated with low melting point metal. By adding to SS316 powder sintering additives such as boron nitride (BN), which reduces the liquidus line temperature, we produce near full-density SS PCs at sintering temperatures much lower than the SS melting temperature, and importantly without any measurable shape distortion. Conversely, the SS PC without BN remains porous after the sintering process and unsuitable for fluidic applications. Since the SS parts, unlike Si, are compatible with machining, they can be modified to work with commercial compression fitting. The PC structures as well as the connection with the fitting are leak-free with relatively high operating pressures. A flexible membrane heater along with a resistance-temperature detector is integrated with the SS PCs for thermal desorption. The proof-of-concept experiment demonstrates that the SS PC can preconcentrate and inject 0.6% headspace toluene to enhance the detector’s response. Full article
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