Detection of volatile organic compounds: From chemical gas sensors to terahertz spectroscopy

Galstyan, Vardan; D’Arco, Annalisa; Fabrizio, Marta Di; Poli, Nicola; Lupi, S.; Comini, Elisabetta

doi:10.1515/revac-2021-0127

Cited by 43 publications

(26 citation statements)

References 221 publications

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“…Chemicals such as VOCs are found in our daily lives. As these compounds are emitted in industrial estates, plants, transport, agriculture, and waste combustion, VOC detection has a variety of applications, such as ensuring human and animal health, protecting the environment, and controlling food quality [ 107 ]. Moreover, VOCs can be generated internally within a person’s body, which are called endogenous VOCs, or outside the body through food consumption or environmental exposure, which are called exogenous VOCs [ 108 ].…”

Section: Sensing Properties Of P-type Mox Thin Filmsmentioning

confidence: 99%

P-Type Metal Oxide Semiconductor Thin Films: Synthesis and Chemical Sensor Applications

Moumen

Kumarage

Comini

2022

Sensors

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This review focuses on the synthesis of p-type metal-oxide (p-type MOX) semiconductor thin films, such as CuO, NiO, Co3O4, and Cr2O3, used for chemical-sensing applications. P-type MOX thin films exhibit several advantages over n-type MOX, including a higher catalytic effect, low humidity dependence, and improved recovery speed. However, the sensing performance of CuO, NiO, Co3O4, and Cr2O3 thin films is strongly related to the intrinsic physicochemical properties of the material and the thickness of these MOX thin films. The latter is heavily dependent on synthesis techniques. Many techniques used for growing p-MOX thin films are reviewed herein. Physical vapor-deposition techniques (PVD), such as magnetron sputtering, thermal evaporation, thermal oxidation, and molecular-beam epitaxial (MBE) growth were investigated, along with chemical vapor deposition (CVD). Liquid-phase routes, including sol–gel-assisted dip-and-spin coating, spray pyrolysis, and electrodeposition, are also discussed. A review of each technique, as well as factors that affect the physicochemical properties of p-type MOX thin films, such as morphology, crystallinity, defects, and grain size, is presented. The sensing mechanism describing the surface reaction of gases with MOX is also discussed. The sensing characteristics of CuO, NiO, Co3O4, and Cr2O3 thin films, including their response, sensor kinetics, stability, selectivity, and repeatability are reviewed. Different chemical compounds, including reducing gases (such as volatile organic compounds (VOCs), H2, and NH3) and oxidizing gases, such as CO2, NO2, and O3, were analyzed. Bulk doping, surface decoration, and heterostructures are some of the strategies for improving the sensing capabilities of the suggested pristine p-type MOX thin films. Future trends to overcome the challenges of p-type MOX thin-film chemical sensors are also presented.

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Section: Sensing Properties Of P-type Mox Thin Filmsmentioning

confidence: 99%

P-Type Metal Oxide Semiconductor Thin Films: Synthesis and Chemical Sensor Applications

Moumen

Kumarage

Comini

2022

Sensors

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“…These systems have promoted the diffusion of THz radiation for spectroscopy applications. Thus, it was applied with success in various scientific fields e.g., gas sensing [75][76][77][78][79][80], chemical and pharmaceutical analysis [81,82], condensed matter [83][84][85], identification of crystalline polymorphs, microelectronics and security [86][87][88][89], agri-food industry [90] and cultural heritage [91], including the emerging support in the field of biomedicine and bio-imaging [92][93][94][95][96][97][98][99], etc. Thus, THz spectroscopy has become a valuable tool for rapid and non-invasive detection thanks to many advantages that make it particularly appealing for probing the intermolecular structure and dynamics of biomolecules [95,100,101].…”

Section: Thz Technology For Protein Spectroscopymentioning

confidence: 99%

Terahertz Spectroscopic Analysis in Protein Dynamics: Current Status

et al. 2022

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Proteins play a key role in living organisms. The study of proteins and their dynamics provides information about their functionality, catalysis and potential alterations towards pathological diseases. Several techniques are used for studying protein dynamics, e.g., magnetic resonance, fluorescence imaging techniques, mid-infrared spectroscopy and biochemical assays. Spectroscopic analysis, based on the use of terahertz (THz) radiation with frequencies between 0.1 and 15 THz (3–500 cm−1), was underestimated by the biochemical community. In recent years, however, the potential of THz spectroscopy in the analysis of both simple structures, such as polypeptide molecules, and complex structures, such as protein complexes, has been demonstrated. The THz absorption spectrum provides some information on proteins: for small molecules the THz spectrum is dominated by individual modes related to the presence of hydrogen bonds. For peptides, the spectral information concerns their secondary structure, while for complex proteins such as globular proteins and viral glycoproteins, spectra also provide information on collective modes. In this short review, we discuss the results obtained by THz spectroscopy in the protein dynamics investigations. In particular, we will illustrate advantages and applications of THz spectroscopy, pointing out the complementary information it may provide.

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“…Optical sensors use different light–matter interactions to detect and quantify targeted analytes . They monitor the optical absorption, emission, light scattering, and reflection or changes in the refractive index of targeted volatiles at defined optical wavelengths. − Optical gas sensors are employed for the sensing of different environmentally important gases. For example, sensors based on chemiluminescence, in which a chemical reaction between a gas and another compound results in light emission, are commonly used for the detection of soil agrochemicals like NO, NO 2 , and NH 3 .…”

Section: Chemical Sensorsmentioning

confidence: 99%

Sensing of Airborne Infochemicals for Green Pest Management: What Is the Challenge?

et al. 2021

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One of the biggest global challenges for our societies is to provide natural resources to the rapidly expanding population while maintaining sustainable and ecologically friendly products. The increasing public concern about toxic insecticides has resulted in the rapid development of alternative techniques based on natural infochemicals (ICs). ICs (e.g., pheromones, allelochemicals, volatile organic compounds) are secondary metabolites produced by plants and animals and used as information vectors governing their interactions. Such chemical language is the primary focus of chemical ecology, where behavior-modifying chemicals are used as tools for green pest management. The success of ecological programs highly depends on several factors, including the amount of ICs that enclose the crop, the range of their diffusion, and the uniformity of their application, which makes precise detection and quantification of ICs essential for efficient and profitable pest control. However, the sensing of such molecules remains challenging, and the number of devices able to detect ICs in air is so far limited. In this review, we will present the advances in sensing of ICs including biochemical sensors mimicking the olfactory system, chemical sensors, and sensor arrays (e-noses). We will also present several mathematical models used in integrated pest management to describe how ICs diffuse in the ambient air and how the structure of the odor plume affects the pest dynamics.

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Detection of volatile organic compounds: From chemical gas sensors to terahertz spectroscopy

Cited by 43 publications

References 221 publications

P-Type Metal Oxide Semiconductor Thin Films: Synthesis and Chemical Sensor Applications

P-Type Metal Oxide Semiconductor Thin Films: Synthesis and Chemical Sensor Applications

Terahertz Spectroscopic Analysis in Protein Dynamics: Current Status

Sensing of Airborne Infochemicals for Green Pest Management: What Is the Challenge?

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