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New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications

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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 (30 September 2022) | Viewed by 19813

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Special Issue Editors

Dr. Anna Staerz

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Guest Editor

Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
Interests: WO3; heterostructures; DRIFT spectroscopy; impedance spectroscopy

Dr. Nicolae Barsan

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Guest Editor

Group Head-Weimar Group, Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, 72076 Tuebingen, Germany
Interests: DRIFT spectroscopy; Kelvin probe measurements; SMOX gas sensors; transduction and reception functions
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Special Issue Information

Dear Colleagues,

The aim of this Special Issue is to highlight research that will advance new directions in semiconducting metal oxide (SMOX)-based gas sensors. SMOX-based gas sensors became commercially available over 50 years ago. Since then, the number of chemo-resistive sensors on the market has significantly grown, and their use has become more widespread, spanning from domestic safety to comfort applications such as indoor air quality monitoring. The research interest in SMOX-based gas sensors has also significantly increased over the years. Despite the maturity of the field and a great deal of research citing new promising materials, most commercially available sensors are still based on the original material SnO₂. In particular, sensors based on heterostructures and composite materials are widely reported to show promising results at lab scale. Systematic studies, including evaluations of reproducibility and stability, new materials, and preparation methods are a crucial first step toward their integration into commercial products.

We cordially invite you to submit original research that systematically examines new sensing materials or preparation methods. Contributors are also invited to present mechanistic advances that complement the traditional transduction and reception mechanisms developed largely on SnO2 with studies on other materials. Studies that outline best testing practices or develop standard testing protocols to ensure applicability are desired. Review papers on these topics are also encouraged.

Dr. Anna Staerz
Dr. Nicolae Barsan
Guest Editors

Manuscript Submission Information

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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

sensor testing procedures
heterostructure and composite materials
systematic and statistics based studies

Published Papers (6 papers)

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Research

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12 pages, 7012 KiB

Open AccessArticle

Study on Sensing Mechanism of Volatile Organic Compounds Using Pt-Loaded ZnO Nanocrystals

by Takeshi Shinkai, Keigo Masumoto, Masaru Iwai, Yusuke Inomata and Tetsuya Kida

Sensors 2022, 22(16), 6277; https://doi.org/10.3390/s22166277 - 20 Aug 2022

Cited by 3 | Viewed by 1898

Abstract

Understanding the surface chemistry of target gases on sensing materials is essential for designing high-performance gas sensors. Here, we report the effect of Pt-loading on the sensing of volatile organic compounds (VOCs) with ZnO gas sensors, demonstrated by diffuse reflection infrared Fourier transform (DRIFT) spectroscopy. Pt-loaded ZnO nanocrystals (NCs) of 13~22 nm are synthesized using the hot soap method. The synthesized powder is deposited on an alumina substrate by screen-printing to form a particulate gas sensing film. The 0.1 wt% Pt-loaded ZnO NC sensor shows the highest sensor response to acetone and ethanol at 350 °C, while the responses to CO and H₂ are small and exhibit good selectivity to VOCs. The gas sensing mechanism of ethanol with Pt-ZnO NCs was studied by in situ DRIFT spectroscopy combined with online FT-IR gas analysis. The results show that ethanol reacts with small Pt-loaded ZnO to produce intermediate species such as acetaldehyde, acetate, and carbonate, which generates a high sensor response to ethanol in air. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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12 pages, 3431 KiB

Open AccessArticle

Highly Sensitive Carbon Monoxide Sensor Element with Wide-Range Humidity Resistance by Loading Pd Nanoparticles on SnO₂ Surface

by Koichi Suematsu, Akihito Uchiyama, Ken Watanabe and Kengo Shimanoe

Sensors 2022, 22(8), 2934; https://doi.org/10.3390/s22082934 - 11 Apr 2022

Cited by 3 | Viewed by 2128

Abstract

To develop a highly sensitive carbon monoxide (CO) sensor with a wide range of humidity resistance, we focused on the Pd loading method on SnO₂ nanoparticles and the thickness of the sensing layer. The Pd nanoparticles were loaded on the SnO₂ surface using the surface immobilization method (SI-Pd/SnO₂) and the colloidal protection method (CP-Pd/SnO₂). The XPS analysis indicated that the Pd nanoparticles were a composite of PdO and Pd, regardless of the loading method. According to the evaluation of the electrical properties at 350 °C, the CO response in a humid atmosphere and the resistance toward humidity change using CP-Pd/SnO₂ were higher than those using SI-Pd/SnO₂, even though the Pd loading amount of SI-Pd/SnO₂ was slightly larger than that of CP-Pd/SnO₂. In addition, Pd/SnO₂ prepared via the CP method with a thinner sensing layer showed a higher sensor response and greater stability to humidity changes at 300 °C, even though the humidity change influenced the CO response at 250 and 350 °C. Thus, the overall design of the surface Pd, including size, dispersity, and oxidation state, and the sensor fabrication, that is, the thickness of the sensing layer, offer a high-performance semiconductor-type CO gas sensor with a wide range of humidity resistance. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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16 pages, 7578 KiB

Open AccessArticle

Low Complexity System on Chip Design to Acquire Signals from MOS Gas Sensor Applications

by Juan B. Talens, Jose Pelegri-Sebastia and Maria Jose Canet

Sensors 2021, 21(19), 6552; https://doi.org/10.3390/s21196552 - 30 Sep 2021

Cited by 2 | Viewed by 1840

Abstract

Analog signals from gas sensors are used to recognize all types of VOC (Volatile Organic Compound) substances, such as toxic gases, tobacco or ethanol. The processes to recognize these substances include acquisition, treatment and machine learning for classification, which can all be efficiently implemented on a Field Programmable Gate Array (FPGA) aided by Low-Voltage Differential Signaling (LVDS). This article proposes a low-cost 11-bit effective number of bits (ENOB) sigma-delta Analog to Digital Converter (ADC), with an SNR of 75.97 dB and an SFDR of 72.28 dB, whose output is presented on screen in real time, thanks to the use of a Linux System on Chip (SoC) system that enables parallelism, high-level programming and provides a working environment for the scientific treatment of gas sensor signals. The high frequency achieved by the implemented ADC allows for multiplexing the capture of several analog signals with an optimal resolution. Additionally, several ADCs can be implemented in the same FPGA so several analog signals can be digitalized in parallel. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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Review

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46 pages, 93339 KiB

Open AccessReview

Green Synthesis of Metal Oxides Semiconductors for Gas Sensing Applications

by Mehran Dadkhah and Jean-Marc Tulliani

Sensors 2022, 22(13), 4669; https://doi.org/10.3390/s22134669 - 21 Jun 2022

Cited by 23 | Viewed by 4470

Abstract

During recent decades, metal oxide semiconductors (MOS) have sparked more attention in various applications and industries due to their excellent sensing characteristics, thermal stability, abundance, and ease of synthesis. They are reliable and accurate for measuring and monitoring environmentally important toxic gases, such as NO₂, NO, N₂O, H₂S, CO, NH₃, CH₄, SO₂, and CO₂. Compared to other sensing technologies, MOS sensors are lightweight, relatively inexpensive, robust, and have high material sensitivity with fast response times. Green nanotechnology is a developing branch of nanotechnology and aims to decrease the negative effects of the production and application of nanomaterials. For this purpose, organic solvents and chemical reagents are not used to prepare metal nanoparticles. On the contrary, the synthesis of metal or metal oxide nanoparticles is done by microorganisms, either from plant extracts or fungi, yeast, algae, and bacteria. Thus, this review aims at illustrating the possible green synthesis of different metal oxides such as ZnO, TiO₂, CeO₂, SnO₂, In₂O₃, CuO, NiO, WO_3, and Fe₃O₄, as well as metallic nanoparticles doping. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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30 pages, 11674 KiB

Open AccessReview

A Review of Gas Measurement Set-Ups

by Łukasz Fuśnik, Bartłomiej Szafraniak, Anna Paleczek, Dominik Grochala and Artur Rydosz

Sensors 2022, 22(7), 2557; https://doi.org/10.3390/s22072557 - 27 Mar 2022

Cited by 9 | Viewed by 6023

Abstract

Measurements of the properties of gas-sensitive materials are a subject of constant research, including continuous developments and improvements of measurement methods and, consequently, measurement set-ups. Preparation of the test set-up is a key aspect of research, and it has a significant impact on the tested sensor. This paper aims to review the current state of the art in the field of gas-sensing measurement and provide overall conclusions of how the different set-ups impact the obtained results. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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24 pages, 2585 KiB

Open AccessReview

Mechanistic Insights into WO₃ Sensing and Related Perspectives

by Mauro Epifani

Sensors 2022, 22(6), 2247; https://doi.org/10.3390/s22062247 - 14 Mar 2022

Cited by 11 | Viewed by 2390

Abstract

Tungsten trioxide (WO₃) is taking on an increasing level of importance as an active material for chemoresistive sensors. However, many different issues have to be considered when trying to understand the sensing properties of WO₃ in order to rationally design sensing devices. In this review, several key points are critically summarized. After a quick review of the sensing results, showing the most timely trends, the complex system of crystallographic WO₃ phase transitions is considered, with reference to the phases possibly involved in gas sensing. Appropriate attention is given to related investigations of first principles, since they have been shown to be a solid support for understanding the physical properties of crucially important systems. Then, the surface properties of WO₃ are considered from both an experimental and first principles point of view, with reference to the paramount importance of oxygen vacancies. Finally, the few investigations of the sensing mechanisms of WO₃ are discussed, showing a promising convergence between the proposed hypotheses and several experimental and theoretical studies presented in the previous sections. Full article

(This article belongs to the Special Issue New Trends in Gas Sensors Based on Semiconductor Metal Oxides: Design and Applications)

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