Nanomaterial-based gas sensors used for breath diagnosis

2020 ◽  
Vol 8 (16) ◽  
pp. 3231-3248 ◽  
Author(s):  
Xinyuan Zhou ◽  
Zhenjie Xue ◽  
Xiangyu Chen ◽  
Chuanhui Huang ◽  
Wanqiao Bai ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Gas Sensors ◽  
Active Sites ◽  
Gas Sensing ◽  
High Surface ◽  
Volume Ratio ◽  
Sensing Applications ◽  
Enormous Number

Gas-sensing applications commonly use nanomaterials (NMs) because of their unique physicochemical properties, including a high surface-to-volume ratio, enormous number of active sites, controllable morphology, and potential for miniaturisation.

scholarly journals A Review of Carbon Nanotubes-Based Gas Sensors

2009 ◽  
Vol 2009 ◽  
pp. 1-24 ◽  
Author(s):  
Yun Wang ◽  
John T. W. Yeow
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Low Cost ◽  
High Surface ◽  
Hollow Structure ◽  
Volume Ratio ◽  
Fast Response ◽  
Sensing Technology ◽  
Structure Of Nanomaterials

Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs) has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

scholarly journals Gas Sensing Properties of Mg-Incorporated Metal–Organic Frameworks

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3323 ◽  
Author(s):  
Jae-Hyoung Lee ◽  
Thanh-Binh Nguyen ◽  
Duy-Khoi Nguyen ◽  
Jae-Hun Kim ◽  
Jin-Young Kim ◽  
...  
Keyword(s):  
Pore Size ◽  
Gas Sensors ◽  
Gas Sensing ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
Kinetic Properties ◽  
Sensing Properties ◽  
Sensing Applications ◽  
Gas Sensing Properties ◽  
Metal Organic

The gas sensing properties of two novel series of Mg-incorporated metal–organic frameworks (MOFs), termed Mg-MOFs-I and -II, were assessed. The synthesized iso-reticular type Mg-MOFs exhibited good crystallinity, high thermal stability, needle-shape morphology and high surface area (up to 2900 m2·g−1), which are promising for gas sensing applications. Gas-sensing studies of gas sensors fabricated from Mg-MOFs-II revealed better sensing performance, in terms of the sensor dynamics and sensor response, at an optimal operating temperature of 200 °C. The MOF gas sensor with a larger pore size and volume showed shorter response and recovery times, demonstrating the importance of the pore size and volume on the kinetic properties of MOF-based gas sensors. The gas-sensing results obtained in this study highlight the potential of Mg-MOFs gas sensors for the practical monitoring of toxic gases in a range of environments.

scholarly journals 2D Materials for Gas Sensing Applications: A Review on Graphene Oxide, MoS2, WS2 and Phosphorene

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3638 ◽  
Author(s):  
Maurizio Donarelli ◽  
Luca Ottaviano
Keyword(s):  
Graphene Oxide ◽  
Gas Sensing ◽  
2D Materials ◽  
High Surface ◽  
Volume Ratio ◽  
Thick Layer ◽  
Research Field ◽  
First Year ◽  
Sensing Applications ◽  
Recent Developments

After the synthesis of graphene, in the first year of this century, a wide research field on two-dimensional materials opens. 2D materials are characterized by an intrinsic high surface to volume ratio, due to their heights of few atoms, and, differently from graphene, which is a semimetal with zero or near zero bandgap, they usually have a semiconductive nature. These two characteristics make them promising candidate for a new generation of gas sensing devices. Graphene oxide, being an intermediate product of graphene fabrication, has been the first graphene-like material studied and used to detect target gases, followed by MoS2, in the first years of 2010s. Along with MoS2, which is now experiencing a new birth, after its use as a lubricant, other sulfides and selenides (like WS2, WSe2, MoSe2, etc.) have been used for the fabrication of nanoelectronic devices and for gas sensing applications. All these materials show a bandgap, tunable with the number of layers. On the other hand, 2D materials constituted by one atomic species have been synthetized, like phosphorene (one layer of black phosphorous), germanene (one atom thick layer of germanium) and silicone (one atom thick layer of silicon). In this paper, a comprehensive review of 2D materials-based gas sensor is reported, mainly focused on the recent developments of graphene oxide, exfoliated MoS2 and WS2 and phosphorene, for gas detection applications. We will report on their use as sensitive materials for conductometric, capacitive and optical gas sensors, the state of the art and future perspectives.

Recent advances in 2D black phosphorus based materials for gas sensing applications

2021 ◽  
Vol 9 (11) ◽  
pp. 3773-3794
Author(s):  
Aaryashree ◽  
Pratik V. Shinde ◽  
Amitesh Kumar ◽  
Dattatray J. Late ◽  
Chandra Sekhar Rout
Keyword(s):  
Physicochemical Properties ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Black Phosphorus ◽  
Sensing Applications ◽  
Recent Advances ◽  
Sensing Material ◽  
Black Phosphorous

Black phosphorous (BP) has emerged as a potential sensing material due to its exceptional physicochemical properties. The review presents both the theoretical and experimental aspects of the BP-based gas sensors.

Rational Synthesis and Optimization of Multifunctional Solid-State Gas Sensors

2004 ◽  
Vol 828 ◽  
Author(s):  
Johannes Schwank ◽  
Ghenadii Korotcenkov
Keyword(s):  
Solid State ◽  
Gas Sensors ◽  
Active Sites ◽  
Gas Sensing ◽  
Heterogeneous Systems ◽  
Sensor Applications ◽  
Sensing Applications ◽  
Long Time ◽  
Overall Performance ◽  
Scale Design

ABSTRACTA new approach is discussed for the rational synthesis and development of optimized multifunctional solid-state gas sensors. Multifunctionality—the incorporation of multiple types of reactivities into a material, such as acid and/or base functionalities, oxidation and/or reduction functionalities, etc.—isa requirement in many gas sensing applications. The front end of many gas sensors contains catalytic layers, so that optimization of catalysts and optimization of gas sensors can be carried out in a synergistic fashion.Multifunctionality presents unique challenges to rational catalyst and sensor systems development because the overall performance of the material is a convolution of the performance of the various subcomponents, and optimization of these individual subcomponents in isolation does not necessarily lead to optimal, or even acceptable, overall performance. A major obstacle to dealing with these difficulties is the inherent complexity of heterogeneous systems prepared by traditional approaches, which makes it difficult to unambiguously identify the compositions and morphologies of the local active sites and their interactions. Further complicating the problem is the requirement to function in environments that can vary on both short and long time scales. A key to understanding, controlling, and optimizing these materials is the ability to produce and study well-defined sensor materials with well-defined composition and morphology, with the flexibility to vary the composition easily without jeopardizing the structural uniformity.The development of new or improved materials for gas sensor applications requires a search for novel and innovative approaches to the nano-scale design of these materials. The use of the technology of surface modification by successive ionic layer deposition (SILD) method is such an innovative approach that will be discussed in this paper.

scholarly journals Influence of Humidity on NO2-Sensing and Selectivity of Spray-CVD Grown ZnO Thin Film above 400 °C

Chemosensors ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 42 ◽  
Author(s):  
Lontio Fomekong ◽  
Saruhan
Keyword(s):  
Thin Film ◽  
Relative Humidity ◽  
Gas Sensing ◽  
High Surface ◽  
Volume Ratio ◽  
Phase Identification ◽  
Selectivity Ratio ◽  
Zno Thin Film ◽  
Sensor Signal ◽  
Sensing Applications

Thin films are being used more and more in gas sensing applications, relying on their high surface area to volume ratio. In this study, ZnO thin film was produced through a thermal aerosol spraying and chemical vapor deposition (spray-CVD) process at 500 °C using zinc acetate as a precursor. The phase identification and the morphologies of the film were investigated by XRD and SEM, respectively. Gas-sensing properties of the ZnO thin film were evaluated toward NO2, CO, and NO at a moderate temperature range (400–500 °C) in dry and humid air (relative humidity = 2.5, 5, 7.5, and 10% RH). The obtained results show good sensor signal for both NO2 (R/R0 = 94%) and CO (92%) and poor sensor signal to NO (52%) at an optimum temperature of 450 °C in dry air. The response and recovery times decrease with the increase of NO2 concentration. In the presence of humidity (10% of RH), the sensor is more than twice as sensitive to NO2 (70%) as CO (29%), and accordingly, exhibits good selectivity toward NO2. As the amount of humidity increases from 2.5 to 10% RH, the selectivity ratio of ZnO thin film to NO2 against CO increases from 1 to 2.4. It was also observed that the response and the recovery rates decrease with the increase of relative humidity. The significant enhancement of the selectivity of ZnO thin film toward NO2 in the presence of humidity was attributed to the strong affinity of OH species with NO2.

scholarly journals Two-Dimensional Nanomaterials for Gas Sensing Applications: The Role of Theoretical Calculations

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 851 ◽  
Author(s):  
Yamei Zeng ◽  
Shiwei Lin ◽  
Ding Gu ◽  
Xiaogan Li
Keyword(s):  
Electric Fields ◽  
Gas Sensing ◽  
Theoretical Calculations ◽  
High Surface ◽  
Volume Ratio ◽  
Two Dimensional ◽  
Sensing Properties ◽  
Sensing Applications ◽  
Gas Sensing Properties ◽  
2D Nanomaterials

Two-dimensional (2D) nanomaterials have attracted a large amount of attention regarding gas sensing applications, because of their high surface-to-volume ratio and unique chemical or physical gas adsorption capabilities. As an important research method, theoretical calculations have been massively applied in predicting the potentially excellent gas sensing properties of these 2D nanomaterials. In this review, we discuss the contributions of theoretical calculations in the study of the gas sensing properties of 2D nanomaterials. Firstly, we elaborate on the gas sensing mechanisms of 2D layered nanomaterials, such as the traditional charge transfer mechanism, and a standard for distinguishing between physical and chemical adsorption, from the perspective of theoretical calculations. Then, we describe how to conduct a theoretical analysis to explain or predict the gas sensing properties of 2D nanomaterials. Thirdly, we discuss three important methods that have been applied in order to improve the gas sensing properties, that is, defect functionalization (vacancy, edge, grain boundary, and doping), heterojunctions, and electric fields. Among these strategies, theoretical calculations play a very important role in explaining the mechanisms underlying the enhanced gas sensing properties. Finally, we summarize both the advantages and limitations of the theoretical calculations, and present perspectives for further research on the 2D nanomaterials-based gas sensors.

scholarly journals Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 783 ◽  
Author(s):  
Andrea Gaiardo ◽  
David Novel ◽  
Elia Scattolo ◽  
Michele Crivellari ◽  
Antonino Picciotto ◽  
...  
Keyword(s):  
Low Power ◽  
Failure Analysis ◽  
Gas Sensors ◽  
High Performance ◽  
Gas Sensing ◽  
Mechanical Failure ◽  
Sensing Applications ◽  
Theoretical Approaches ◽  
Sensing Material ◽  
Silicon Bulk

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

scholarly journals Advanced development of metal oxide nanomaterials for H2 gas sensing applications

2021 ◽  
Author(s):  
Yushu Shi ◽  
Huiyan Xu ◽  
Tongyao Liu ◽  
Shah Zeb ◽  
Yong Nie ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensors ◽  
Gas Sensing ◽  
The Past ◽  
Sensing Applications ◽  
The Future ◽  
Metal Oxide Nanomaterials ◽  
Nanomaterials Synthesis ◽  
Advanced Development

The scheme of the structure of this review includes an introduction from the metal oxide nanomaterials’ synthesis to application in H2 gas sensors—a vision from the past to the future.

scholarly journals Three-dimensional platinum nanoparticle-based bridges for ammonia gas sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nishchay A. Isaac ◽  
Johannes Reiprich ◽  
Leslie Schlag ◽  
Pedro H. O. Moreira ◽  
Mostafa Baloochi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Response Times ◽  
High Surface ◽  
Three Dimensional ◽  
Performance Testing ◽  
Volume Ratio ◽  
Platinum Nanoparticle ◽  
Ammonia Gas ◽  
Lift Off

AbstractThis study demonstrates the fabrication of self-aligning three-dimensional (3D) platinum bridges for ammonia gas sensing using gas-phase electrodeposition. This deposition scheme can guide charged nanoparticles to predetermined locations on a surface with sub-micrometer resolution. A shutter-free deposition is possible, preventing the use of additional steps for lift-off and improving material yield. This method uses a spark discharge-based platinum nanoparticle source in combination with sequentially biased surface electrodes and charged photoresist patterns on a glass substrate. In this way, the parallel growth of multiple sensing nodes, in this case 3D self-aligning nanoparticle-based bridges, is accomplished. An array containing 360 locally grown bridges made out of 5 nm platinum nanoparticles is fabricated. The high surface-to-volume ratio of the 3D bridge morphology enables fast response and room temperature operated sensing capabilities. The bridges are preconditioned for ~ 24 h in nitrogen gas before being used for performance testing, ensuring drift-free sensor performance. In this study, platinum bridges are demonstrated to detect ammonia (NH3) with concentrations between 1400 and 100 ppm. The sensing mechanism, response times, cross-sensitivity, selectivity, and sensor stability are discussed. The device showed a sensor response of ~ 4% at 100 ppm NH3 with a 70% response time of 8 min at room temperature.

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