Artigos de revistas: "Chemiresistive gas sensor"

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Schober, Sebastian A., Yosra Bahri, Cecilia Carbonelli e Robert Wille. "Neural Network Robustness Analysis Using Sensor Simulations for a Graphene-Based Semiconductor Gas Sensor". Chemosensors 10, n.º 5 (21 de abril de 2022): 152. http://dx.doi.org/10.3390/chemosensors10050152.

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Despite their advantages regarding production costs and flexibility, chemiresistive gas sensors often show drawbacks in reproducibility, signal drift and ageing. As pattern recognition algorithms, such as neural networks, are operating on top of raw sensor signals, assessing the impact of these technological drawbacks on the prediction performance is essential for ensuring a suitable measuring accuracy. In this work, we propose a characterization scheme to analyze the robustness of different machine learning models for a chemiresistive gas sensor based on a sensor simulation model. Our investigations are structured into four separate studies: in three studies, the impact of different sensor instabilities on the concentration prediction performance of the algorithms is investigated, including sensor-to-sensor variations, sensor drift and sensor ageing. In a further study, the explainability of the machine learning models is analyzed by applying a state-of-the-art feature ranking method called SHAP. Our results show the feasibility of model-based algorithm testing and substantiate the need for the thorough characterization of chemiresistive sensor algorithms before sensor deployment in order to ensure robust measurement performance.

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Zhou, Guangying, Bingsheng Du, Jie Zhong, Le Chen, Yuyu Sun, Jia Yue, Minglang Zhang et al. "Advances in Gas Detection of Pattern Recognition Algorithms for Chemiresistive Gas Sensor". Materials 17, n.º 21 (24 de outubro de 2024): 5190. http://dx.doi.org/10.3390/ma17215190.

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Gas detection and monitoring are critical to protect human health and safeguard the environment and ecosystems. Chemiresistive sensors are widely used in gas monitoring due to their ease of fabrication, high customizability, mechanical flexibility, and fast response time. However, with the rapid development of industrialization and technology, the main challenges faced by chemiresistive gas sensors are poor selectivity and insufficient anti-interference stability in complex application environments. In order to overcome these shortcomings of chemiresistive gas sensors, the pattern recognition method is emerging and is having a great impact in the field of sensing. In this review, we focus systematically on the advancements in the field of data processing methods for feature extraction, such as the methods of determining the characteristics of the original response curve, the curve fitting parameters, and the transform domain. Additionally, we emphasized the developments of traditional recognition algorithms and neural network algorithm in gas discrimination and analyzed the advantages through an extensive literature review. Lastly, we summarized the research on chemiresistive gas sensors and provided prospects for future development.

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Kim, Myeong Gyu, e Yun-Hyuk Choi. "Gas-Sensing Properties of Co9S8 Films Toward Formaldehyde, Ethanol, and Hydrogen Sulfide". Materials 17, n.º 23 (24 de novembro de 2024): 5743. http://dx.doi.org/10.3390/ma17235743.

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The chemiresistive gas-sensing properties of pristine Co9S8 film are little known despite its potential as a promising gas sensor material due to its intrinsic characteristics. In this study, a pristine polycrystalline Co9S8 film (approximately 440 nm in thickness) is fabricated by depositing a Co3O4 film followed by sulfidation to investigate its gas-sensing properties. The prepared Co9S8 film sensor is found to exhibit high responsiveness towards formaldehyde (HCHO), ethanol (C2H5OH), and hydrogen sulfide (H2S) at operating temperatures of 300 °C and 400 °C, with strong concentration dependence. On the other hand, the sensor shows very low or no responsiveness towards hydrogen (H2), acetone (CH3COCH3), and nitrogen dioxide (NO2). These results enhance our understanding of the intrinsic gas-sensing properties of Co9S8, aiding in the design and fabrication of high-performance chemiresistive gas sensors based on Co9S8.

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Bezdek, Máté J., Shao-Xiong Lennon Luo, Kang Hee Ku e Timothy M. Swager. "A chemiresistive methane sensor". Proceedings of the National Academy of Sciences 118, n.º 2 (31 de dezembro de 2020): e2022515118. http://dx.doi.org/10.1073/pnas.2022515118.

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A chemiresistive sensor is described for the detection of methane (CH4), a potent greenhouse gas that also poses an explosion hazard in air. The chemiresistor allows for the low-power, low-cost, and distributed sensing of CH4 at room temperature in air with environmental implications for gas leak detection in homes, production facilities, and pipelines. Specifically, the chemiresistors are based on single-walled carbon nanotubes (SWCNTs) noncovalently functionalized with poly(4-vinylpyridine) (P4VP) that enables the incorporation of a platinum-polyoxometalate (Pt-POM) CH4 oxidation precatalyst into the sensor by P4VP coordination. The resulting SWCNT-P4VP-Pt-POM composite showed ppm-level sensitivity to CH4 and good stability to air as well as time, wherein the generation of a high-valent platinum intermediate during CH4 oxidation is proposed as the origin of the observed chemiresistive response. The chemiresistor was found to exhibit selectivity for CH4 over heavier hydrocarbons such as n-hexane, benzene, toluene, and o-xylene, as well as gases, including carbon dioxide and hydrogen. The utility of the sensor in detecting CH4 using a simple handheld multimeter was also demonstrated.

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Je, Yeonjin, e Sang-Soo Chee. "Controlling the Morphology of Tellurene for a High-Performance H2S Chemiresistive Room-Temperature Gas Sensor". Nanomaterials 13, n.º 19 (5 de outubro de 2023): 2707. http://dx.doi.org/10.3390/nano13192707.

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A two-dimensional (2D) van der Waals material composed only of tellurium (Te) atoms—tellurene—is drawing attention because of its high intrinsic electrical conductivity and strong interaction with gas molecules, which could allow the development of high-performance chemiresistive sensors. However, the correlation between the morphologies and gas detection properties of tellurene has not yet been studied in depth, and few reports exist on tellurene-based hydrogen sulfide (H2S) chemiresistive sensors in spite of their strong interaction with H2S molecules. Here, we investigate the morphology-dependent H2S gas detection properties of tellurene synthesized using a hydrothermal method. To tailor the morphologies of tellurene, the molecular weight of the surfactant was controlled, revealing that a 1D or 2D form was synthesized and also accompanied with the high crystallinity. The 1D tellurene-based chemiresistive sensor presented superior H2S detection properties compared to the 2D form, achieving a gas response (Rg/Ra) of ~38, even at room temperature. This outstanding performance was attributed to the high intrinsic electrical conductivity and high specific surface area of the resultant 1D tellurene.

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Zhang, Run, Cong Qin, Hari Bala, Yan Wang e Jianliang Cao. "Recent Progress in Spinel Ferrite (MFe2O4) Chemiresistive Based Gas Sensors". Nanomaterials 13, n.º 15 (27 de julho de 2023): 2188. http://dx.doi.org/10.3390/nano13152188.

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Gas-sensing technology has gained significant attention in recent years due to the increasing concern for environmental safety and human health caused by reactive gases. In particular, spinel ferrite (MFe2O4), a metal oxide semiconductor with a spinel structure, has emerged as a promising material for gas-sensing applications. This review article aims to provide an overview of the latest developments in spinel-ferrite-based gas sensors. It begins by discussing the gas-sensing mechanism of spinel ferrite sensors, which involves the interaction between the target gas molecules and the surface of the sensor material. The unique properties of spinel ferrite, such as its high surface area, tunable bandgap, and excellent stability, contribute to its gas-sensing capabilities. The article then delves into recent advancements in gas sensors based on spinel ferrite, focusing on various aspects such as microstructures, element doping, and heterostructure materials. The microstructure of spinel ferrite can be tailored to enhance the gas-sensing performance by controlling factors such as the grain size, porosity, and surface area. Element doping, such as incorporating transition metal ions, can further enhance the gas-sensing properties by modifying the electronic structure and surface chemistry of the sensor material. Additionally, the integration of spinel ferrite with other semiconductors in heterostructure configurations has shown potential for improving the selectivity and overall sensing performance. Furthermore, the article suggests that the combination of spinel ferrite and semiconductors can enhance the selectivity, stability, and sensing performance of gas sensors at room or low temperatures. This is particularly important for practical applications where real-time and accurate gas detection is crucial. In conclusion, this review highlights the potential of spinel-ferrite-based gas sensors and provides insights into the latest advancements in this field. The combination of spinel ferrite with other materials and the optimization of sensor parameters offer opportunities for the development of highly efficient and reliable gas-sensing devices for early detection and warning systems.

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Schober, Sebastian A., Cecilia Carbonelli e Robert Wille. "Simulating Defects in Environmental Sensor Networks Using Stochastic Sensor Models". Engineering Proceedings 6, n.º 1 (17 de maio de 2021): 88. http://dx.doi.org/10.3390/i3s2021dresden-10094.

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Chemiresistive gas sensors are an important tool for monitoring air quality in cities and large areas due to their low cost and low power and, hence, the ability to densely distribute them. Unfortunately, such sensor systems are prone to defects and faults over time such as sensitivity loss of the sensing material, less effective heating of the surface due to battery loss, or random output errors in the sensor electronics, which can lead to signal jumps or sensor stopping. Although these defects usually can be compensated, either algorithmically or physically, this requires an accurate screening of the entire sensor system for such defects. In order to properly develop, test, and benchmark corresponding screening algorithms, however, methods for simulating gas sensor networks and their defects are essential. In this work, we propose such a simulation method based on a stochastic sensor model for chemiresistive sensor systems. The proposed method rests on the idea of simulating the defect-causing processes directly on the sensor surface as a stochastic process and is capable of simulating various defects which can occur in low-cost sensor technologies. The work aims to show the scope and principles of the proposed simulator as well as to demonstrate its applicability using exemplary use cases.

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Dougami, Naganori, Takeshi Miyata, Taishi Orita, Tadashi Nakatani, Rui Kakunaka, Takafumi Taniguchi, Hirokazu Mitsuhashi e Shoichiro Nakao. "Hot-wire-type micromachined chemiresistive gas sensors for battery-powered city gas alarms". Japanese Journal of Applied Physics 64, n.º 1 (1 de janeiro de 2025): 01SP13. https://doi.org/10.35848/1347-4065/ada29c.

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Abstract Metal oxide semiconductor (MOX) chemiresistive gas sensors used in gas alarms have contributed to the safe use of city gas and liquid petroleum gas. In this study, we successfully fabricated hot-wire-type MOX sensors using micro-electro-mechanical systems (MEMS) technology. The hot-wire type structure, in which an electrode plays dual roles in detecting and heating, was adopted for efficient production. Owing to the miniaturization together with the thermal insulation, the sensors exhibited a fast thermal response. The average power consumption of the sensor in the pulsed operation was less than 100 μW. The sensor exhibited high sensitivity of more than 100 mV to 3000 ppm methane and showed low cross-sensitivity to interference gases such as ethanol and hydrogen. These sensing properties were retained for more than five years, demonstrating excellent long-term stability of the sensors.

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Huang, Baoyu, Xinwei Tong, Xiangpeng Zhang, Qiuxia Feng, Marina N. Rumyantseva, Jai Prakash e Xiaogan Li. "MXene/NiO Composites for Chemiresistive-Type Room Temperature Formaldehyde Sensor". Chemosensors 11, n.º 4 (21 de abril de 2023): 258. http://dx.doi.org/10.3390/chemosensors11040258.

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In this work, MXene/NiO-composite-based formaldehyde (HCHO) sensing materials were successfully synthesized by an in situ precipitation method. The heterostructures between the MXene and NiO nanoparticles were verified by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The HCHO sensing performance of the MXene/NiO-based chemiresistive-type sensors was investigated. Compared to pure MXene and NiO materials, the sensing performance of the MXene/NiO-P2-based sensor to HCHO gas at room temperature was significantly enhanced by the formation of MXene/NiO heterojunctions. The response of the MXene/NiO-P2 sensor to 50 ppm HCHO gas was 8.8, which was much higher than that of the pure MXene and NiO. At room temperature, the detectable HCHO concentration of the MXene/NiO-P2-based sensor was 1 ppm, and the response and recovery time to 2 ppm HCHO was 279 s and 346 s, respectively. The MXene/NiO-P2 sensor also exhibited a good selectivity and a long-term stability to HCHO gas for 56 days. The in situ Fourier transform infrared (FTIR) spectra of the MXene/NiO-P2 sensor, when exposed to HCHO gas at different times, were investigated to verify the adsorption reaction products of HCHO molecules.

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Yang, Taicong, Fengchun Tian, James A. Covington, Feng Xu, Yi Xu, Anyan Jiang, Junhui Qian, Ran Liu, Zichen Wang e Yangfan Huang. "Resistance-Capacitance Gas Sensor Based on Fractal Geometry". Chemosensors 7, n.º 3 (15 de julho de 2019): 31. http://dx.doi.org/10.3390/chemosensors7030031.

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An important component of any chemiresistive gas sensor is the way in which the resistance of the sensing film is interrogated. The geometrical structure of an electrode can enhance the performance of a gas-sensing device and in particular the performance of sensing films with large surface areas, such as carbon nanotubes. In this study, we investigated the influence of geometrical structure on the performance of gas sensors, combining the characteristics of carbon nanotubes with a novel gas sensor electrode structure based on fractal geometry. The fabricated sensors were tested with exposure to nitric oxide, measuring both the sensor resistance and capacitance (RC) of the sensor responses. Experimental results showed that the sensors with fractal electrode structures had a superior performance over sensors with traditional geometrical structures. Moreover, the RC characteristics of these fractal sensors could be further improved by using different test frequencies that could aid in the identification and quantification of a target gas.

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Wei, Minghui, Xuerong Shi, Min Zhu, Shengming Zhang, Heng Zhang, Haiyu Yao e Shusheng Xu. "Research Progress on Chemiresistive Carbon Monoxide Sensors". Nanomaterials 15, n.º 4 (16 de fevereiro de 2025): 303. https://doi.org/10.3390/nano15040303.

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The development of high-performance carbon monoxide (CO) sensors is essential for protecting human health, ensuring industrial safety, and maintaining environmental well-being. Among various types of sensors, chemiresistive sensors exhibit considerable promise for real-time applications due to their operational capabilities. To achieve high performances of chemiresistive sensors, this review emphasizes various enhancement strategies, encompassing the refinement of sensing materials, the augmentation of sensor structures, and the optimization of gas recognition algorithms. Specifically, the modification techniques of sensing materials, which include the construction of heterostructures, the decoration with noble metals, surface functionalization, hetero-element-doping, and morphology engineering, are delved into comprehensively. This review provides insights into the rational design of cost-effective CO sensors.

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Adamek, Martin, Jiri Mlcek, Nela Skowronkova, Magdalena Zvonkova, Miroslav Jasso, Anna Adamkova, Josef Skacel et al. "3D Printed Fused Deposition Modeling (FDM) Capillaries for Chemiresistive Gas Sensors". Sensors 23, n.º 15 (31 de julho de 2023): 6817. http://dx.doi.org/10.3390/s23156817.

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This paper discusses the possible use of 3D fused deposition modeling (FDM) to fabricate capillaries for low-cost chemiresistive gas sensors that are often used in various applications. The disadvantage of these sensors is low selectivity, but 3D printed FDM capillaries have the potential to increase their selectivity. Capillaries with 1, 2 and 3 tiers with a length of 1.5 m, 3.1 m and 4.7 m were designed and manufactured. Food and goods available in the general trade network were used as samples (alcohol, seafood, chicken thigh meat, acetone-free nail polish remover and gas from a gas lighter) were also tested. The “Vodka” sample was used as a standard for determining the effect of capillary parameters on the output signal of the MiCS6814 sensor. The results show the shift of individual parts of the signal in time depending on the parameters of the capillary and the carrier air flow. A three-tier capillary was chosen for the comparison of gas samples with each other. The graphs show the differences between individual samples, not only in the height of the output signal but also in its time characteristic. The tested 3D printed FDM capillaries thus made it possible to characterize the output response by also using an inexpensive chemiresistive gas sensor in the time domain.

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Kumawat, Meenakshi, Devyani Thapliyal, George D. Verros, Raj Kumar Arya, Sanghamitra Barman, Gopinath Halder e Pooja Shandilya. "PANI-Based Hydrogen Sulfide Gas Sensors". Coatings 12, n.º 2 (31 de janeiro de 2022): 186. http://dx.doi.org/10.3390/coatings12020186.

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A hydrogen sulfide gas-sensitive chemiresistive sensor was screen printed on a flexible polyethylene terphthalate substrate using a nanocomposite of polyaniline(PANI)/WO3/CuCl2 (PET). FE-SEM analysis validated the nanoscale morphology of the composite, which revealed tungsten oxide particles in nano-rectangular forms, i.e., rod-like structures. The gas-sensing capabilities of the film were affected by the PANI and WO3 ratio, with the optimal ratio of 0.5 showing the best response. It was tested at various H2S gas concentrations and demonstrated a progressive response as the gas concentration increased. PANI/WO3/CuCl2 film was more sensitive than PANI/CuCl2 binary composite film. Around 1 ppm of gas concentration, with a response time of 67.9 s at room temperature, the highest response of two orders of magnitude change was observed, of 93%. This study found that PANI/WO3/CuCl2 is an excellent composite for improving the reversibility and humidity sensitivity of PANI/CuCl2 composite-based chemiresistors during H2S gas sensing, and that screen printing is a simple and cost-effective method for producing stable and uniform film-based chemiresistive gas sensors.

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Meka, Divakara, Linda A. George e Shalini Prasad. "Triethanolamine Nanocomposite-based Chemiresistive Nitrogen Dioxide Gas Sensor". Journal of the Association for Laboratory Automation 14, n.º 2 (abril de 2009): 69–75. http://dx.doi.org/10.1016/j.jala.2008.08.007.

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Chen, Xiaohu, Ryan Wreyford e Noushin Nasiri. "Recent Advances in Ethylene Gas Detection". Materials 15, n.º 17 (23 de agosto de 2022): 5813. http://dx.doi.org/10.3390/ma15175813.

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The real-time detecting and monitoring of ethylene gas molecules could benefit the agricultural, horticultural and healthcare industries. In this regard, we comprehensively review the current state-of-the-art ethylene gas sensors and detecting technologies, covering from preconcentrator-equipped gas chromatographic systems, Fourier transform infrared technology, photonic crystal fiber-enhanced Raman spectroscopy, surface acoustic wave and photoacoustic sensors, printable optically colorimetric sensor arrays to a wide range of nanostructured chemiresistive gas sensors (including the potentiometric and amperometric-type FET-, CNT- and metal oxide-based sensors). The nanofabrication approaches, working conditions and sensing performance of these sensors/technologies are carefully discussed, and a possible roadmap for the development of ethylene detection in the near future is proposed.

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Jiang, Yang, Ning Tang, Cheng Zhou, Ziyu Han, Hemi Qu e Xuexin Duan. "A chemiresistive sensor array from conductive polymer nanowires fabricated by nanoscale soft lithography". Nanoscale 10, n.º 44 (2018): 20578–86. http://dx.doi.org/10.1039/c8nr04198a.

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Kruse, Peter. "(Invited) Chemiresistive Water Quality Sensors: Challenges and Progress". ECS Meeting Abstracts MA2022-01, n.º 52 (7 de julho de 2022): 2135. http://dx.doi.org/10.1149/ma2022-01522135mtgabs.

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Chemiresistors are solid state devices that change their electronic properties (more specifically, the resistance of a conductive thin film or percolation network) as a result of chemical interactions with their environment. They are a well-established and widely commercialized technology for gas or vapor sensor applications. The active layer may consist of metal oxides, polymers, nanomaterials or composites. In most cases, chemisorption or catalytic activity involving the analyte results in surface doping of the active layer, although other mechanisms (such as conductivity changes due to swelling) have also been reported. A significant part of the sensing literature is taken up by reports of ChemFETs, in which case the conductivity of the active layer can also be modulated by an applied gate voltage. Gate voltage modulation is helpful for establishing the sensing mechanism and - on occasion - for distinguishing multiple simultaneous target analytes. In most cases, however, the actual sensor operation occurs at zero gate voltage, thus reducing the ChemFET to a chemiresistor. [1] Gas sensors can be operated at high voltages and without shielding the contacts to the film from gas exposure, two simplifications that are not afforded to sensors operating in aqueous environments. Water quality sensors are a surprisingly underserved area of sensor applications.[2] Important chemical water quality parameters include pH, dissolved gases, common ions and a range of toxic trace contaminants which may be ionic or uncharged, inorganic or organic. All these water quality parameters are usually monitored using colorimetric sensors, electrochemical sensors and large lab-based instruments. None of these lend themselves to low maintenance, reagent free, low power continuous operation for online monitoring. In particular, colorimetric sensors need a resupply of reagents and electrochemical sensors require reference electrodes. Chemiresistors have the potential to eliminate all these disadvantages, but there has been slow progress in adapting them to aqueous analytes. They are simple and economical to manufacture, and can operate reagent-free and with low or no maintenance. Unlike electrochemical sensors they do not require reference electrodes. Challenges include the need to prevent electrical shorts through the aqueous medium and the need to keep the sensing voltage low enough to avoid electrochemical reactions at the sensor. We have built a chemiresistive sensing platform for aqueous media. The active sensor element consists of a percolation network of low-dimensional materials particles that form a conducting film, e.g. from carbon nanotubes, pencil trace, exfoliated graphene or MoS2. The first members of that platform were free chlorine sensors,[3-5] but we have also demonstrated pH sensitive films [6,7] and cation sensors.[8] While there are some challenges associated with expanding the range of accessible analytes,[9] we have recently expanded the applicability of our platform, in particular anions and cations that are commonly present as pollutants in surface and drinking water. Our sensors can be incorporated into a variety of systems and will also be suitable for online monitoring in remote and resource-poor locations. References: [1] A. Zubiarrain-Laserna and P. Kruse, Graphene-Based Water Quality Sensors. J. Electrochem. Soc. 167 (2020) 037539. [2] P. Kruse, Review on Water Quality Sensors. J. Phys. D 51 (2018) 203002. [3] L. H. H. Hsu, E. Hoque, P. Kruse, and P. R. Selvaganapathy, A carbon nanotube based resettable sensor for measuring free chlorine in drinking water. Appl. Phys. Lett. 106 (2015) 063102. [4] E. Hoque, L. H. H. Hsu, A. Aryasomayajula, P. R. Selvaganapathy, and P. Kruse, Pencil-Drawn Chemiresistive Sensor for Free Chlorine in Water. IEEE Sens. Lett. 1 (2017) 4500504. [5] A. Mohtasebi, A. D. Broomfield, T. Chowdhury, P. R. Selvaganapathy, and P. Kruse, Reagent-Free Quantification of Aqueous Free Chlorine via Electrical Readout of Colorimetrically Functionalized Pencil Lines. ACS Appl. Mater. Interfaces 9 (2017) 20748-20761. [6] D. Saha, P. R. Selvaganapathy and P. Kruse, Peroxide-Induced Tuning of the Conductivity of Nanometer-Thick MoS2 Films for Solid State Sensors. ACS Appl. Nano Mater. 3 (2020) 10864-10877. [7] S. Angizi, E. Y. C. Yu, J. Dalmieda, D. Saha, P. R. Selvaganapathy and P. Kruse, Defect Engineering of Graphene to Modulate pH Response of Graphene Devices. Langmuir 37 (2021) 12163-12178. [8] J. Dalmieda, A. Zubiarrain-Laserna, D. Ganepola, P. R. Selvaganapathy and P. Kruse, Chemiresistive Detection of Silver Ions in Aqueous Media. Sens. Actuators B:Chem 328 (2021) 129023. [9] J. Dalmieda, A. Zubiarrain-Laserna, D. Saha, P. R. Selvaganapathy and P. Kruse, Impact of Surface Adsorption on Metal-Ligand Binding of Phenanthrolines. J. Phys. Chem. C 125 (2021) 21112-21123. Figure 1

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Mankar, R. B., e V. D. Kapse. "Cerium Modified Nanocrystalline SmFeO3 for Ethanol Sensing". Oriental Journal Of Chemistry 40, n.º 2 (30 de abril de 2024): 362–68. http://dx.doi.org/10.13005/ojc/400206.

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Presently, detection of ethanol has become essential in various fields due to its adverse effects on human beings. For selective detection of ethanol, chemiresistive gas sensors are widely investigated. Modified ABO3 type perovskites have shown their potential in the fabrication of chemiresistive gas sensors. In present work, SmFeO3 perovskite oxide based thick films were fabricated and surface modified with cerium by simple dipping technique. The structural properties of the samples were studied by Field EEmission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray spectrometer (EDS). The results of FE-SEM indicate that average grain size was in nano range and Ce-modified SmFeO3 films were comparatively more porous than pure SmFeO3 film. This porous nature of film favors gas sensing mechanism. The results of EDS suggest that Ce was deposited on the surface of SmFeO3 films. The gas response of pure SmFeO3 film was tested towards LPG, CO2, NH3, H2, C2H5OH, Cl2, and H2S gases and observed that SmFeO3 film exhibited good response to ethanol (C2H5OH). Among modified samples, Ce-modified SmFeO3 film (dipping time 5 min) exhibited excellent ethanol sensing properties such as , maximum response (16.87 at 1000C ), response time (24 sec), recovery time (34 sec), excellent stability, and good selectivity towards ethanol. Thus Ce-modified SmFeO3 is a potential material in the fabrication of ethanol sensor. The impacts of Ce modification on the gas sensing performance of the SmFeO3 sensor ware discussed in detail.

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Jha, Ravindra Kumar, Aman Nanda e Navakanta Bhat. "Ultrasonication assisted fabrication of a tungsten sulfide/tungstite heterostructure for ppb-level ammonia detection at room temperature". RSC Advances 10, n.º 37 (2020): 21993–2001. http://dx.doi.org/10.1039/d0ra02553d.

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A tungsten sulfide/tungstite heterostructure is prepared via a modified liquid exfoliation technique. A chemiresistive sensor based on this nanomaterial demonstrates excellent sensitivity and selectivity towards ammonia gas even at room temperature.

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Manikandan, V., Iulian Petrila, S. Vigneselvan, R. S. Mane, Bogdan Vasile, Raghu Dharmavarapu, Stefan Lundgaard, Saulius Juodkazis e J. Chandrasekaran. "A reliable chemiresistive sensor of nickel-doped tin oxide (Ni-SnO2) for sensing carbon dioxide gas and humidity". RSC Advances 10, n.º 7 (2020): 3796–804. http://dx.doi.org/10.1039/c9ra09579a.

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Fedorov, Fedor S., Maksim A. Solomatin, Margitta Uhlemann, Steffen Oswald, Dmitry A. Kolosov, Anatolii Morozov, Alexey S. Varezhnikov et al. "Quasi-2D Co3O4 nanoflakes as an efficient gas sensor versus alcohol VOCs". Journal of Materials Chemistry A 8, n.º 15 (2020): 7214–28. http://dx.doi.org/10.1039/d0ta00511h.

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Lin, Chia-Yu, Po-Chin Nien, Wei-Yi Feng, Chii-Wann Lin, Jim Tunney e Kuo-Chuan Ho. "Chemiresistive NO Gas Sensor Based on Zinc Oxide Nanorods". Journal of Bionanoscience 2, n.º 2 (1 de dezembro de 2008): 102–8. http://dx.doi.org/10.1166/jbns.2008.032.

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Babar, B. M., S. H. Sutar, S. H. Mujawar, S. S. Patil, U. D. Babar, U. T. Pawar, P. M. Kadam, P. S. Patil e L. D. Kadam. "V2O5-rGO based chemiresistive gas sensor for NO2 detection". Materials Science and Engineering: B 298 (dezembro de 2023): 116827. http://dx.doi.org/10.1016/j.mseb.2023.116827.

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Kodu, Margus, Artjom Berholts, Tauno Kahro, Jens Eriksson, Rositsa Yakimova, Tea Avarmaa, Indrek Renge, Harry Alles e Raivo Jaaniso. "Highly Sensitive NH3 Sensors Using CVD and Epitaxial Graphene Functionalised with Vanadium(V) Oxide: A Comparative Study". Proceedings 2, n.º 13 (20 de novembro de 2018): 854. http://dx.doi.org/10.3390/proceedings2130854.

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Exceptionally sensitive and selective graphene-based chemiresistive gas sensors were produced as a result of graphene functionalisation with a sub-nanometer V2O5 layer by using the method of pulsed laser deposition. Two different types of graphene were used—epitaxial graphene on SiC and CVD graphene on Si/SiO2—and both showed remarkable enhancement of sensing properties in terms of response and recovery speed, response magnitude and selectiveness towards NH3 gas. The epitaxial graphene-based sensor was demonstrating the highest relative response towards ammonia amounting to 80% for 0.1 ppm NH3.

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Pazniak, Hanna, Ilya A. Plugin, Polina M. Sheverdyaeva, Laetitia Rapenne, Alexey S. Varezhnikov, Antonio Agresti, Sara Pescetelli et al. "Alcohol Vapor Sensor Based on Quasi-2D Nb2O5 Derived from Oxidized Nb2CTz MXenes". Sensors 24, n.º 1 (20 de dezembro de 2023): 38. http://dx.doi.org/10.3390/s24010038.

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MXenes are two-dimensional (2D) materials with a great potential for sensor applications due to their high aspect ratio and fully functionalized surface that can be tuned for specific gas adsorption. Here, we demonstrate that the Nb2CTz-based sensor exhibits high performance towards alcohol vapors at temperatures up to 300–350 °C, with the best sensitivity towards ethanol. We attribute the observed remarkable chemiresistive effect of this material to the formation of quasi-2D Nb2O5 sheets as the result of the oxidation of Nb-based MXenes. These findings are supported by synchrotron X-ray photoelectron spectroscopy studies together with X-ray diffraction and electron microscopy observations. For analyte selectivity, we employ a multisensor approach where the gas recognition is achieved by linear discriminant analysis of the vector response of the on-chip sensor array. The reported protocol demonstrates that MXene layers are efficient precursors for the derivation of 2D oxide architectures, which are suitable for developing gas sensors and sensor arrays.

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Jayaramulu, Kolleboyina, Marilyn Esclance DMello, Kamali Kesavan, Andreas Schneemann, Michal Otyepka, Stepan Kment, Chandrabhas Narayana et al. "A multifunctional covalently linked graphene–MOF hybrid as an effective chemiresistive gas sensor". Journal of Materials Chemistry A 9, n.º 32 (2021): 17434–41. http://dx.doi.org/10.1039/d1ta03246a.

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The covalent linkage of graphene acid (GA) with amine-functionalized UiO-66-NH2via an amide bond. The resultant hybrid GA@UiO-66-NH2 acts as a chemiresistive CO2 sensor wth significant efficiency owing to its unique structural features.

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Fu, Li, Shixi You, Guangjun Li, Xingxing Li e Zengchang Fan. "Application of Semiconductor Metal Oxide in Chemiresistive Methane Gas Sensor: Recent Developments and Future Perspectives". Molecules 28, n.º 18 (20 de setembro de 2023): 6710. http://dx.doi.org/10.3390/molecules28186710.

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The application of semiconductor metal oxides in chemiresistive methane gas sensors has seen significant progress in recent years, driven by their promising sensitivity, miniaturization potential, and cost-effectiveness. This paper presents a comprehensive review of recent developments and future perspectives in this field. The main findings highlight the advancements in material science, sensor fabrication techniques, and integration methods that have led to enhanced methane-sensing capabilities. Notably, the incorporation of noble metal dopants, nanostructuring, and hybrid materials has significantly improved sensitivity and selectivity. Furthermore, innovative sensor fabrication techniques, such as thin-film deposition and screen printing, have enabled cost-effective and scalable production. The challenges and limitations facing metal oxide-based methane sensors were identified, including issues with sensitivity, selectivity, operating temperature, long-term stability, and response times. To address these challenges, advanced material science techniques were explored, leading to novel metal oxide materials with unique properties. Design improvements, such as integrated heating elements for precise temperature control, were investigated to enhance sensor stability. Additionally, data processing algorithms and machine learning methods were employed to improve selectivity and mitigate baseline drift. The recent developments in semiconductor metal oxide-based chemiresistive methane gas sensors show promising potential for practical applications. The improvements in sensitivity, selectivity, and stability achieved through material innovations and design modifications pave the way for real-world deployment. The integration of machine learning and data processing techniques further enhances the reliability and accuracy of methane detection. However, challenges remain, and future research should focus on overcoming the limitations to fully unlock the capabilities of these sensors. Green manufacturing practices should also be explored to align with increasing environmental consciousness. Overall, the advances in this field open up new opportunities for efficient methane monitoring, leak prevention, and environmental protection.

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Tang, Xiaohui, Jean-Pierre Raskin, Nicolas Reckinger, Yiyi Yan, Nicolas André, Driss Lahem e Marc Debliquy. "Enhanced Gas Detection by Altering Gate Voltage Polarity of Polypyrrole/Graphene Field-Effect Transistor Sensor". Chemosensors 10, n.º 11 (9 de novembro de 2022): 467. http://dx.doi.org/10.3390/chemosensors10110467.

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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.

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Lim, Namsoo, Jae-Sung Lee e Young Tae Byun. "Negatively-Doped Single-Walled Carbon Nanotubes Decorated with Carbon Dots for Highly Selective NO2 Detection". Nanomaterials 10, n.º 12 (14 de dezembro de 2020): 2509. http://dx.doi.org/10.3390/nano10122509.

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In this study, we demonstrated a highly selective chemiresistive-type NO2 gas sensor using facilely prepared carbon dot (CD)-decorated single-walled carbon nanotubes (SWCNTs). The CD-decorated SWCNT suspension was characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible spectroscopy, and then spread onto an SiO2/Si substrate by a simple and cost-effective spray-printing method. Interestingly, the resistance of our sensor increased upon exposure to NO2 gas, which was contrary to findings previously reported for SWCNT-based NO2 gas sensors. This is because SWCNTs are strongly doped by the electron-rich CDs to change the polarity from p-type to n-type. In addition, the CDs to SWCNTs ratio in the active suspension was critical in determining the response values of gas sensors; here, the 2:1 device showed the highest value of 42.0% in a sensing test using 4.5 ppm NO2 gas. Furthermore, the sensor selectively responded to NO2 gas (response ~15%), and to other gases very faintly (NO, response ~1%) or not at all (CO, C6H6, and C7H8). We propose a reasonable mechanism of the CD-decorated SWCNT-based sensor for NO2 sensing, and expect that our results can be combined with those of other researches to improve various device performances, as well as for NO2 sensor applications.

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Gao, Tuo, Yongchen Wang, Yi Luo, Chengwu Zhang, Zachariah Pittman, Alexandra Oliveira, Howard Craig, Jing Zhao e Brian G. Willis. "Fast and Reversible Chemiresistive Sensors for Robust Detection of Organic Vapors Using Oleylamine-Functionalized Palladium Nanoparticles". International Journal of High Speed Electronics and Systems 27, n.º 03n04 (setembro de 2018): 1840027. http://dx.doi.org/10.1142/s012915641840027x.

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Chemiresistive sensors fabricated by oleylamine-functionalized palladium nanoparticles (OLA-PdNP) have been studied in hydrogen sensing, but not so much in organic vapor sensing. Like the extensively studied gold nanoparticles-based gas sensors, palladium nanoparticles also give the ease of surface modification and large surface-area-to-volume ratio. In this study, we demonstrate an OLA-PdNP chemiresistor array with robust sensor responses (1-15% of ΔR/R0) and accurate discrimination of six organic vapors at a concentration of p/p0 = 0.2, using principal component analysis (PCA). Each microfabricated 36 mm2 chip has 36 individual sensors. By incorporating multiple sensors on one chip, the sensor response gives a distinguishable pattern for each analyte. From this study, an electronic chemical spectrometer can be further developed by incorporating many types of ligands on palladium metal core to enhance sensor accuracy and precision.

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Kumar, Sanjeev, Navdeep Kaur, Anshul Kumar Sharma, Aman Mahajan e R. K. Bedi. "Improved Cl2 sensing characteristics of reduced graphene oxide when decorated with copper phthalocyanine nanoflowers". RSC Advances 7, n.º 41 (2017): 25229–36. http://dx.doi.org/10.1039/c7ra02212c.

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A novel gas sensing platform involving a hybrid of reduced graphene oxide (rGO) sheets with unsubstituted copper phthalocyanine (CuPc) nanoflowers has been explored as a room temperature ppb level chemiresistive chlorine (Cl₂) sensor with a detection limit as low as 1.97 ppb.

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Sun, Kai, Guanghui Zhan, Hande Chen e Shiwei Lin. "Low-Operating-Temperature NO2 Sensor Based on a CeO2/ZnO Heterojunction". Sensors 21, n.º 24 (10 de dezembro de 2021): 8269. http://dx.doi.org/10.3390/s21248269.

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CeO2/ZnO-heterojunction-nanorod-array-based chemiresistive sensors were studied for their low-operating-temperature and gas-detecting characteristics. Arrays of CeO2/ZnO heterojunction nanorods were synthesized using anodic electrodeposition coating followed by hydrothermal treatment. The sensor based on this CeO2/ZnO heterojunction demonstrated a much higher sensitivity to NO2 at a low operating temperature (120 °C) than the pure-ZnO-based sensor. Moreover, even at room temperature (RT, 25 °C) the CeO2/ZnO-heterojunction-based sensor responds linearly and rapidly to NO2. This sensor’s reaction to interfering gases was substantially less than that of NO2, suggesting exceptional selectivity. Experimental results revealed that the enhanced gas-sensing performance at the low operating temperature of the CeO2/ZnO heterojunction due to the built-in field formed after the construction of heterojunctions provides additional carriers for ZnO. Thanks to more carriers in the ZnO conduction band, more oxygen and target gases can be adsorbed. This explains the enhanced gas sensitivity of the CeO2/ZnO heterojunction at low operating temperatures.

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Zvonkova, Magdalena, Martin Adamek, Nela Skowronkova, Stepan Dlabaja, Jiri Matyas, Miroslav Jasso, Anna Adamkova, Jiri Mlcek, Richardos Nikolaos Salek e Martin Buran. "Compact 3D-Printed Unit for Separation of Simple Gas Mixtures Combined with Chemiresistive Sensors". Sensors 24, n.º 13 (6 de julho de 2024): 4391. http://dx.doi.org/10.3390/s24134391.

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Inexpensive chemiresistive sensors are often insufficiently selective as they are sensitive to multiple components of the gas mixture at the same time. One solution would be to insert a device in front of the sensor that separates the measured gas mixture and possibly isolates the unwanted components. This study focused on the fabrication and characterization of a compact unit, which was fabricated by 3D printing, for the separation and detection of simple gas mixtures. The capillary, the basic part of the compact unit, was 4.689 m long and had a diameter of 0.7 mm. The compact unit also contained a mixing chamber on the inlet side and a measuring chamber with a MiCS-6814 sensor on the outlet side. Mixtures of ethanol and water at different concentrations were chosen for characterization. The measured calibration curve was found to have a reliability of R2 = 0.9941. The study further addressed the elements of environmental friendliness of the materials used and their sustainability.

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Sakhuja, Neha, Ravindra Kumar Jha e Navakanta Bhat. "Tungsten Disulphide Nanosheets for High-Performance Chemiresistive Ammonia Gas Sensor". IEEE Sensors Journal 19, n.º 24 (15 de dezembro de 2019): 11767–74. http://dx.doi.org/10.1109/jsen.2019.2936978.

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Shao, Shaofeng, Hongyan Wu, Fan Jiang, Shimin Wang, Tao Wu, Yating Lei, Ralf Koehn e Wei-Feng Rao. "Regulable switching from p- to n-type behavior of ordered nanoporous Pt-SnO2 thin films with enhanced room temperature toluene sensing performance". RSC Advances 6, n.º 27 (2016): 22878–88. http://dx.doi.org/10.1039/c5ra24736e.

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In this work, a nanoporous SnO₂ sensing film is fabricated in situ on a sensing device using a block polymer template and is applied as a chemiresistive gas sensor. The ordered film is capable of detecting 10 ppm toluene at room temperature and shows good stability.

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Kodu, Margus, Tea Avarmaa, Hugo Mändar, Rando Saar e Raivo Jaaniso. "Structure-Dependent CO2 Gas Sensitivity of La2O2CO3 Thin Films". Journal of Sensors 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/9591081.

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Rare earth oxycarbonates are potential candidate materials for constructing simple and low-cost chemiresistive sensors for monitoring carbon dioxide (CO2) gas in the living and working environment for personal comfort and health reasons. Also, measurement of CO2 concentrations is needed in many industrial processes. Specifically, sol-gel made nanoparticles of Nd and La oxycarbonates have been studied previously as novel CO2 gas sensor materials. In this paper, pulsed laser deposition of La oxycarbonate (La2O2CO3) thin films was studied and structural properties of obtained thin films were characterized. Also, CO2 gas sensing ability of synthesized films was evaluated. The films deposited under CO2 partial pressure in various conditions were all Raman amorphous. In situ or ex situ annealing procedure at high CO2 partial pressure was needed for obtaining crystalline La2O2CO3 films, whereby hexagonal and monoclinic polymorphs were obtained in ex situ and in situ processes, respectively. Sensor structure, made using in situ process, was sensitive to CO2 gas and showed relatively fast response and recovery characteristics.

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Petrushenko, Sergey I., Mateusz Fijalkowski, Kinga Adach, Denis Fedonenko, Yevhenii M. Shepotko, Sergei V. Dukarov, Volodymyr M. Sukhov, Alina L. Khrypunova e Natalja P. Klochko. "Low-Temperature, Highly Sensitive Ammonia Sensors Based on Nanostructured Copper Iodide Layers". Chemosensors 13, n.º 2 (22 de janeiro de 2025): 29. https://doi.org/10.3390/chemosensors13020029.

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Chemiresistive ammonia gas sensors with a low limit of detection of 0.15 ppm and moisture-independent characteristics based on p-type copper iodide (CuI) semiconductor films have been developed. CuI films were deposited on glass and polyethylene terephthalate (PET) substrates using a Successive Ionic Layer Adsorption and Reaction method to fabricate CuI/glass and CuI/PET gas sensors, respectively. They have a nanoscale morphology, an excess iodine and sulfur impurity content, a zinc blende γ-CuI crystal structure with a grain size of ~34 nm and an optical band gap of about 2.95 eV. The high selective sensitivity of both sensors to NH3 is explained by the formation of the [Cu(NH3)2]+ complex. At 5 °C, the responses to 3 ppm ammonia in air in terms of the relative resistance change were 24.5 for the CuI/glass gas sensor and 28 for the CuI/PET gas sensor, with short response times of 50 s to 210 s and recovery times of 10–70 s. The sensors have a fast response–recovery and their performance was well maintained after long-term stability testing for 45 days. After 1000 repeated bends of the flexible CuI/PET gas sensor in different directions, with bending angles up to 180° and curvature radii up to 0.25 cm, the response changes were only 3%.

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Sysoev, Vitalii I., Mikhail O. Bulavskiy, Dmitry V. Pinakov, Galina N. Chekhova, Igor P. Asanov, Pavel N. Gevko, Lyubov G. Bulusheva e Alexander V. Okotrub. "Chemiresistive Properties of Imprinted Fluorinated Graphene Films". Materials 13, n.º 16 (11 de agosto de 2020): 3538. http://dx.doi.org/10.3390/ma13163538.

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The electrical conductivity of graphene materials is strongly sensitive to the surface adsorbates, which makes them an excellent platform for the development of gas sensor devices. Functionalization of the surface of graphene opens up the possibility of adjusting the sensor to a target molecule. Here, we investigated the sensor properties of fluorinated graphene films towards exposure to low concentrations of nitrogen dioxide NO2. The films were produced by liquid-phase exfoliation of fluorinated graphite samples with a composition of CF0.08, CF0.23, and CF0.33. Fluorination of graphite using a BrF3/Br2 mixture at room temperature resulted in the covalent attachment of fluorine to basal carbon atoms, which was confirmed by X-ray photoelectron and Raman spectroscopies. Depending on the fluorination degree, the graphite powders had a different dispersion ability in toluene, which affected an average lateral size and thickness of the flakes. The films obtained from fluorinated graphite CF0.33 showed the highest relative response ca. 43% towards 100 ppm NO2 and the best recovery ca. 37% at room temperature.

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Chen, Xiyu, Min Zeng, Jianhua Yang, Nantao Hu, Xiaoyong Duan, Wei Cai, Yanjie Su e Zhi Yang. "Two-Dimensional Bimetallic Phthalocyanine Covalent-Organic-Framework-Based Chemiresistive Gas Sensor for ppb-Level NO2 Detection". Nanomaterials 13, n.º 10 (17 de maio de 2023): 1660. http://dx.doi.org/10.3390/nano13101660.

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Two-dimensional (2D) phthalocyanine-based covalent organic frameworks (COFs) provide an ideal platform for efficient and rapid gas sensing—this can be attributed to their regular structure, moderate conductivity, and a large number of scalable metal active centers. However, there remains a need to explore structural modification strategies for optimizing the sluggish desorption process caused by the extensive porosity and strong adsorption effect of metal sites. Herein, we reported a 2D bimetallic phthalocyanine-based COF (COF-CuNiPc) as chemiresistive gas sensors that exhibited a high gas-sensing performance to nitrogen dioxide (NO2). Bimetallic COF-CuNiPc with an asymmetric synergistic effect achieves a fast adsorption/desorption process to NO2. It is demonstrated that the COF-CuNiPc can detect 50 ppb NO2 with a recovery time of 7 s assisted by ultraviolet illumination. Compared with single-metal phthalocyanine-based COFs (COF-CuPc and COF-NiPc), the bimetallic structure of COF-CuNiPc can provide a proper band gap to interact with NO2 gas molecules. The CuNiPc heterometallic active site expands the overlap of d-orbitals, and the optimized electronic arrangement accelerates the adsorption/desorption processes. The concept of a synergistic effect enabled by bimetallic phthalocyanines in this work can provide an innovative direction to design high-performance chemiresistive gas sensors.

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Chiou, Jin-Chern, Chin-Cheng Wu e Tse-Mei Lin. "Sensitivity Enhancement of Acetone Gas Sensor using Polyethylene Glycol/Multi-Walled Carbon Nanotubes Composite Sensing Film with Thermal Treatment". Polymers 11, n.º 3 (5 de março de 2019): 423. http://dx.doi.org/10.3390/polym11030423.

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There is a need to develop a chemiresistive gas sensor equipped with a thermostat over a wide area for the sensor, which can protect the sensor from the influence of ambient temperature due to the uniform temperature of the thermostat. In this paper, we demonstrated an acetone gas sensor based on a polyethylene glycol (PEG)/Multi-walled Carbon Nanotubes (MWCNTs) composite film, which was equipped with a thermostat. The sensor was operated at modest working temperatures for sensor sensitivity enhancement. The optimum design of the polyimide-based thermostat with widely uniform thermal distribution was investigated in detail. It was found that the temperature uniformity of the thermostat was achieved using double spiral geometry. The experimental results of the sensor response showed that the PEG/MWCNTs composite film with a moderate working temperature revealed a higher sensitivity than that without thermal treatment. Moreover, the sensing mechanisms of the PEG/MWCNTs composite gas sensor to acetone vapor were studied as well.

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Sysoev, Victor V., Andrey V. Lashkov, Alexey Lipatov, Ilya A. Plugin, Michael Bruns, Dirk Fuchs, Alexey S. Varezhnikov, Mustahsin Adib, Martin Sommer e Alexander Sinitskii. "UV-Light-Tunable p-/n-Type Chemiresistive Gas Sensors Based on Quasi-1D TiS3 Nanoribbons: Detection of Isopropanol at ppm Concentrations". Sensors 22, n.º 24 (14 de dezembro de 2022): 9815. http://dx.doi.org/10.3390/s22249815.

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The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as well as with heating up to 110 °C, and under an ultraviolet (UV) radiation at λ = 345 nm. We found that the RT/UV conditions result in a n-type chemiresistive response to isopropanol, which seems to be governed by its redox reactions with chemisorbed oxygen species. In contrast, the RT conditions without a UV exposure produced a p-type response that is possibly caused by the enhancement of the electron transport scattering due to the analyte adsorption. By analyzing the vector signal from the entire on-chip multisensor array, we could distinguish isopropanol from benzene, both of which produced similar responses on individual sensors. We found that the heating up to 110 °C reduces both the sensitivity and selectivity of the sensor array.

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Wagner, Ricarda, Daniela Schönauer-Kamin e Ralf Moos. "Novel Operation Strategy to Obtain a Fast Gas Sensor for Continuous ppb-Level NO2 Detection at Room Temperature Using ZnO—A Concept Study with Experimental Proof". Sensors 19, n.º 19 (23 de setembro de 2019): 4104. http://dx.doi.org/10.3390/s19194104.

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A novel sensor operation concept for detecting ppb-level NO2 concentrations at room temperature is introduced. Today’s research efforts are directed to make the sensors as fast as possible (low response and recovery times). Nevertheless, hourly mean values can hardly be precisely calculated, as the sensors are still too slow and show baseline drifts. Therefore, the integration error becomes too large. The suggested concept follows exactly the opposite path. The sensors should be made as slow as possible and operated as resistive gas dosimeters. The adsorption/desorption equilibrium should be completely shifted to the adsorption side during a sorption phase. The gas-sensitive material adsorbs each NO2 molecule (dose) impinging and the sensor signal increases linearly with the NO2 dose. The actual concentration value results from the time derivative, which makes the response very fast. When the NO2 adsorption capacity of the sensor material is exhausted, it is regenerated with ultraviolet (UV) light and the baseline is reached again. Since the baseline is newly redefined after each regeneration step, no baseline drift occurs. Because each NO2 molecule that reaches the sensor material contributes to the sensor signal, a high sensitivity results. The sensor behavior of ZnO known so far indicates that ZnO may be suitable to be applied as a room-temperature chemiresistive NO2 dosimeter. Because UV enhances desorption of sorbed gas species from the ZnO surface, regeneration by UV light should be feasible. An experimental proof demonstrating that the sensor concept works at room temperature for ppb-level NO2 concentrations and low doses is given.

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Polyakov, Maxim, Victoria Ivanova, Darya Klyamer, Baybars Köksoy, Ahmet Şenocak, Erhan Demirbaş, Mahmut Durmuş e Tamara Basova. "A Hybrid Nanomaterial Based on Single Walled Carbon Nanotubes Cross-Linked via Axially Substituted Silicon (IV) Phthalocyanine for Chemiresistive Sensors". Molecules 25, n.º 9 (29 de abril de 2020): 2073. http://dx.doi.org/10.3390/molecules25092073.

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In this work, the novel hybrid nanomaterial SWCNT/SiPc made of single walled carbon nanotubes (SWCNT) cross-linked via axially substituted silicon (IV) phthalocyanine (SiPc) was studied as the active layer of chemiresistive layers for the detection of ammonia and hydrogen. SWCNT/SiPc is the first example of a carbon-based nanomaterial in which an axially substituted phthalocyanine derivative is used as a linker. The prepared hybrid material was characterized by spectroscopic methods, thermogravimetry, scanning and transmission electron microscopies. The layers of the prepared hybrid were tested as sensors toward ammonia and hydrogen by a chemiresistive method at different temperatures and relative humidity as well as in the presence of interfering gases like carbon dioxide, hydrogen sulfide and volatile organic vapors. The hybrid layers exhibited the completely reversible sensor response to both gases at room temperature; the recovery time was 100–200 s for NH3 and 50–120 s in the case of H2 depending on the gas concentrations. At the relative humidity (RH) of 20%, the sensor response was almost the same as that measured at RH 5%, whereas the further increase of RH led to its 2–3 fold decrease. It was demonstrated that the SWCNT/SiPc layers can be successfully used for the detection of both NH3 and H2 in the presence of CO2. On the contrary, H2S was found to be an interfering gas for the NH3 detection.

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Nagare, Amruta B., Namdev S. Harale, Sawanta S. Mali, Sarita S. Nikam, Pramod S. Patil, Chang Kook Hong e Annasaheb V. Moholkar. "Chemiresistive ammonia gas sensor based on branched nanofibrous polyaniline thin films". Journal of Materials Science: Materials in Electronics 30, n.º 13 (29 de maio de 2019): 11878–87. http://dx.doi.org/10.1007/s10854-019-01514-7.

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Chang, Won Suk, Jung Hyun Kim, Daeho Kim, Sung Ho Cho e Seung Kwon Seol. "Individually Addressable Suspended Conducting-Polymer Wires in a Chemiresistive Gas Sensor". Macromolecular Chemistry and Physics 215, n.º 17 (28 de julho de 2014): 1633–38. http://dx.doi.org/10.1002/macp.201400220.

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Filipovic, Lado, e Siegfried Selberherr. "Application of Two-Dimensional Materials towards CMOS-Integrated Gas Sensors". Nanomaterials 12, n.º 20 (18 de outubro de 2022): 3651. http://dx.doi.org/10.3390/nano12203651.

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During the last few decades, the microelectronics industry has actively been investigating the potential for the functional integration of semiconductor-based devices beyond digital logic and memory, which includes RF and analog circuits, biochips, and sensors, on the same chip. In the case of gas sensor integration, it is necessary that future devices can be manufactured using a fabrication technology which is also compatible with the processes applied to digital logic transistors. This will likely involve adopting the mature complementary metal oxide semiconductor (CMOS) fabrication technique or a technique which is compatible with CMOS due to the inherent low costs, scalability, and potential for mass production that this technology provides. While chemiresistive semiconductor metal oxide (SMO) gas sensors have been the principal semiconductor-based gas sensor technology investigated in the past, resulting in their eventual commercialization, they need high-temperature operation to provide sufficient energies for the surface chemical reactions essential for the molecular detection of gases in the ambient. Therefore, the integration of a microheater in a MEMS structure is a requirement, which can be quite complex. This is, therefore, undesirable and room temperature, or at least near-room temperature, solutions are readily being investigated and sought after. Room-temperature SMO operation has been achieved using UV illumination, but this further complicates CMOS integration. Recent studies suggest that two-dimensional (2D) materials may offer a solution to this problem since they have a high likelihood for integration with sophisticated CMOS fabrication while also providing a high sensitivity towards a plethora of gases of interest, even at room temperature. This review discusses many types of promising 2D materials which show high potential for integration as channel materials for digital logic field effect transistors (FETs) as well as chemiresistive and FET-based sensing films, due to the presence of a sufficiently wide band gap. This excludes graphene from this review, while recent achievements in gas sensing with graphene oxide, reduced graphene oxide, transition metal dichalcogenides (TMDs), phosphorene, and MXenes are examined.

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Gargiulo, Valentina, Michela Alfè, Laura Giordano e Stefano Lettieri. "Materials for Chemical Sensing: A Comprehensive Review on the Recent Advances and Outlook Using Ionic Liquids, Metal–Organic Frameworks (MOFs), and MOF-Based Composites". Chemosensors 10, n.º 8 (22 de julho de 2022): 290. http://dx.doi.org/10.3390/chemosensors10080290.

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The ability to measure and monitor the concentration of specific chemical and/or gaseous species (i.e., “analytes”) is the main requirement in many fields, including industrial processes, medical applications, and workplace safety management. As a consequence, several kinds of sensors have been developed in the modern era according to some practical guidelines that regard the characteristics of the active (sensing) materials on which the sensor devices are based. These characteristics include the cost-effectiveness of the materials’ manufacturing, the sensitivity to analytes, the material stability, and the possibility of exploiting them for low-cost and portable devices. Consequently, many gas sensors employ well-defined transduction methods, the most popular being the oxidation (or reduction) of the analyte in an electrochemical reactor, optical techniques, and chemiresistive responses to gas adsorption. In recent years, many of the efforts devoted to improving these methods have been directed towards the use of certain classes of specific materials. In particular, ionic liquids have been employed as electrolytes of exceptional properties for the preparation of amperometric gas sensors, while metal–organic frameworks (MOFs) are used as highly porous and reactive materials which can be employed, in pure form or as a component of MOF-based functional composites, as active materials of chemiresistive or optical sensors. Here, we report on the most recent developments relative to the use of these classes of materials in chemical sensing. We discuss the main features of these materials and the reasons why they are considered interesting in the field of chemical sensors. Subsequently, we review some of the technological and scientific results published in the span of the last six years that we consider among the most interesting and useful ones for expanding the awareness on future trends in chemical sensing. Finally, we discuss the prospects for the use of these materials and the factors involved in their possible use for new generations of sensor devices.

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Nam, Bumhee, Tae-Kyung Ko, Soong-Keun Hyun e Chongmu Lee. "CO Sensing Properties of Chemiresistive In2O3/SnO2 Composite Nanoparticle Sensors". Journal of Nanoscience and Nanotechnology 20, n.º 7 (1 de julho de 2020): 4344–48. http://dx.doi.org/10.1166/jnn.2020.17577.

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In2O3/SnO2 composite nanoparticles (NPs) were synthesized by a hydrothermal method. Fringes and spotty patterns were observed in high-resolution TEM images and corresponding selected area electron diffraction pattern, respectively, suggesting the nanoparticles were single crystals. X-ray diffraction results revealed that the In2O3/SnO2 composite NP sensor consisted of three phases: In2O3, SnO2 and In2Sn2O7−x (indium tin oxide: ITO). Energy-dispersive X-ray spectrum of the 9:1 In2O3/SnO2 composite NPs showed the atomic ratio of In2O3 to SnO2 was close to 9:1. The response of the chemiresistive sensor to CO was 9.2, which is within the highest 15% among the response values reported for the past 10 years. The ITO NP-based gas sensor is selective toward CO against other reducing gases such as toluene, acetone and benzene. The enhanced response of the 9:1 In2O3/SnO2 composite NP sensor to CO compared to the pure In2O3 NP sensor can be explained mainly by the stronger resistance modulation at the In2O3/SnO2 junctions.

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Kodu, Margus, Rainer Pärna, Tea Avarmaa, Indrek Renge, Jekaterina Kozlova, Tauno Kahro e Raivo Jaaniso. "Gas-Sensing Properties of Graphene Functionalized with Ternary Cu-Mn Oxides for E-Nose Applications". Chemosensors 11, n.º 8 (15 de agosto de 2023): 460. http://dx.doi.org/10.3390/chemosensors11080460.

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Chemiresistive gas sensors were produced by functionalizing graphene with a ~3 nm layer of mixed oxide xCu2O⸱yMnO using pulsed laser deposition (PLD) from a hopcalite CuMn2O4 target. Sensor response time traces were recorded for strongly oxidizing (NO2, O3) and reducing (NH3, H2S) poisonous gases at ppb and ppm levels, respectively. The morphology of the MOX layer was modified by growth temperature during PLD, resulting in the optimization of the sensor response. Differences in decomposition or oxidation rates on catalytically active metal oxide (MOX) were utilized to achieve partial selectivity for pairs of gases that have similar adsorption and redox properties. The predominant selectivity towards ozone in most samples at different measuring conditions remained difficult to suppress. A distinct selectivity for H2S emerged at higher measurement temperatures (100–150 °C), which was assigned to catalytic oxidation with O2. Several gas–MOX interaction mechanisms were advanced to tentatively explain the sensor behavior, including reversible electron transfer in the simplest case of NO2, decomposition via ionic transients for O3, and complex catalytic oxidative transformations for NH3 and H2S.

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Hwa, Yeongsik, Yeonjin Je, Hyunsung Jung e Sang-Soo Chee. "Enhanced Reliability of NO₂ Chemiresistive Room Temperature Sensor Based on SnSe_X and Its Module Integration". ECS Meeting Abstracts MA2024-02, n.º 65 (22 de novembro de 2024): 4370. https://doi.org/10.1149/ma2024-02654370mtgabs.

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Two-dimensional SnSeX (X = 1, 2) are becoming increasingly recognized as a semiconductor-type gas sensor at room temperature, owing to their high mobility, high speed, and low-power consumption. They particularly present excellent NO2 detection properties due to the strong interaction with NO2 molecules, whereas the reliability of their resultant sensors has been still unclear. To enhance the reliabilities of SnSeX sensors, intensive investigation of well-constructed single-phase SnSe and SnSe2 is significantly essential, unlike relying on additional modification to boost gas responses. Here, we explore the quantitative phase transition using the phase regulator, 1-dodecanethiol (1-DDT) to prepare well-constructed SnSeX, in the hydrothermal synthesis. As the amount of 1-DDT was controlled from 0 μL to 1200 μL, the orthorhombic SnSe phase gradually transformed into SnSe2, exhibiting a superior gas response of 1450% when exposed to 5 ppm of NO2. This well-constructed SnSe2 also exhibited highly reliable gas detection properties, despite the repeated extreme changes in NO2 gas concentration (500 ppb to 5 ppm) under humidity condition. This is because highly crystalline SnSe2 was synthesized by optimal amount of 1-DDT. Using optimal SnSe2, we finally integrated a NO2 gas sensor module capable of monitoring NO2 gas of unknown concentration.

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