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In the field of water decontamination, the design of luminance sensor for sensitive detection of heavy metal ion toxic and nitroaromatic compounds are important and challenging. Herein, a new luminescent Cd(II) metal–organic framework (MOF), {[Cd2(H2O)3(4‐CPCA)2]·2H2O}n (SNUT‐27) (H2(4‐CPCA) = 1‐(4‐carboxyphenyl)‐4‐oxo‐1,4‐dihydropyridazine‐3‐carboxylic acid) was obtained by the reaction of flexible ligand H2(4‐CPCA) and Cd(II) ions, characterized by single crystal X‐ray diffraction, PXRD, FT‐IR, and TGA, the samples were further analyzed. The analysis of single crystal X‐ray diffraction showed that SNUT‐27 possesses a distinct three‐dimensional spatial arrangement and demonstrates impressive fluorescence properties. Particularly, SNUT‐27 showed a highly sensitive response to the nitro‐aromatic compounds nitrobenzene by fluorescence quenching, and in contrast, showed a fluorescence enhancement response to Al3+ and Cu2+. SNUT‐27 can be effortlessly recycled by simply rinsing with water post‐sensing experiments, showcasing its reusability. Additionally, potential detection mechanisms have been explored. [ABSTRACT FROM AUTHOR]

The rising global population and improved living standards have led to an alarming increase in non‐communicable diseases, notably cardiovascular and chronic respiratory diseases, posing a severe threat to human health. Wearable sensing devices, utilizing micro‐sensing technology for real‐time monitoring, have emerged as promising tools for disease prevention. Among various sensing platforms, graphene‐based sensors have shown exceptional performance in the field of micro‐sensing. Laser‐induced graphene (LIG) technology, a cost‐effective and facile method for graphene preparation, has gained particular attention. By converting polymer films directly into patterned graphene materials at ambient temperature and pressure, LIG offers a convenient and environmentally friendly alternative to traditional methods, opening up innovative possibilities for electronic device fabrication. Integrating LIG‐based sensors into health monitoring systems holds the potential to revolutionize health management. To commemorate the tenth anniversary of the discovery of LIG, this work provides a comprehensive overview of LIG's evolution and the progress of LIG‐based sensors. Delving into the diverse sensing mechanisms of LIG‐based sensors, recent research advances in the domain of health monitoring are explored. Furthermore, the opportunities and challenges associated with LIG‐based sensors in health monitoring are briefly discussed. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is currently a widespread element with key roles in telecommunication, sustainable energy, and military industries, among others. Its significant toxicity determines the need to realize sensors for water, air, and soil and the industrial process monitoring of Sb species. Unfortunately, no antimony sensors exist so far, and just laboratory analysis methods are in use. We aimed to contribute to the development of optical sensors for the metalloid by tailoring, for the first time, luminescent Ru(II) and Re(I) polypyridyl complexes to probe and quantify the presence of Sb(III). The molecular design of the complexes includes the multifunctional Sb-binding 2-(2,2′-bithien-5-yl)-1H-imidazo[4,5-f]-1,10-phenanthroline (btip) ligand that ensures the molecular binding of Sb(III) in organic media. The Ru(II)-btip complex is additionally endowed with one 2,2′-bipyrazine (bpz) or two 1,4,5,8-tetraazaphenanthrene (tap) ligands, namely [Ru(bpz)(btip)2]2+ and [Ru(tap)2(btip)]2+, that boost the excited state oxidation potential of the probe, leading to an intramolecular photoinduced electron transfer from btip to the Ru(II) core. The latter is suppressed upon interaction with Sb(III), leading to an 11-fold increase in both the luminescence intensity and lifetime of [Ru(bpz)(btip)2]2+ in the presence of ca. 50 μmol L−1 of SbCl3 in organic medium. The fluorescence intensity of [Re(CO)3(H2O)(btip)]+ also increases upon interaction with Sb(III) but to a much lesser extent due to the intraligand π*→π nature of its emission compared to the Ru(II) ligand-to-metal excited state deactivation. However, the weak π*→d emission band in the red spectral region of the former is quenched by the semimetallic element. The sensing mechanisms of the Ru(II)- and Re(I)-btip probes that allow luminescence intensity (Ru, Re), ratiometric (Ru), and lifetime measurements (Ru) are compared and discussed in this initial solution sensing study. [ABSTRACT FROM AUTHOR]

Formaldehyde, one of the simplest reactive carbonyl substances, is involved in many physiological and pathological processes in living organisms. There is a large amount of data showing that abnormal elevation of formaldehyde is associated with a variety of diseases in the body, such as neurodegenerative diseases, Alzheimer's disease, cardiovascular diseases and cancer, and is also a representative carcinogen, so monitoring formaldehyde is of great importance for disease diagnosis and treatment. In this review, In this paper, we summarize and classify the last ten years of probes for the detection of formaldehyde according to different reaction mechanisms and discuss the structures and applications of the probes. Finally, we briefly describe the challenges and possible solutions in this field. We believe that more new probes provide powerful tools to study the function of formaldehyde in living systems. [ABSTRACT FROM AUTHOR]

MOFs have garnered significant attention as multifunctional materials with substantial potential in the field of water treatment, particularly in the context of heavy metal detection and removal applications. This review focuses on the latest research developments publication, highlighting the applications of MOFs for heavy metal detection and removal from water sources. The review provides an insightful overview of the cutting-edge advancements within this timeframe, showcasing the pivotal role of MOFs in the recognition and removal of heavy metal cations. The discussion encompasses an exploration of various sensing mechanisms, innovative design strategies, and optimization techniques. These aspects collectively highlight the potential of MOFs to revolutionize real-time and precise monitoring of heavy metal ion concentrations in water, offering a pathway towards proactive water quality management. [ABSTRACT FROM AUTHOR]

Two isostructural rare earth metal–organic frameworks, namely [Re2(BBTC)(DMF)5Cl2]·2DMF·H2O [BBTC4– = 1,1'-butadiynebenzene-3,3',5,5'-tetracarboxylate, Re = Y (1) and Ho (2)], have been prepared via solvothermal reaction. Single crystal X − ray analyses reveal that complexes 1 and 2 both crystallize in the P21/m space group. Topological analyses suggest that these frameworks possess the same two–dimensional (2D) (4,4)-connected networks. Notably, the emission spectrum reveals the fluorescence of complex 1 is mainly from the ligands to ligands charge transfer transition. Further investigation indicates that complex 1 can act as a fluorescent sensor for highly sensitive and selective detection of Fe3+ and 2,4,6-trinitrophenol (TNP) in MeCN solution, the quenching constants (Ksv) are 1.45 × 105 M−1 for Fe3+ and 4.08 × 104 M−1 for TNP, with the detection limit (LOD) of 0.12 µM for Fe3+ and 0.52 µM for TNP. Furthermore, the possible sensing mechanisms of complex 1 as bifunctional sensors have been studied based on experiments. Two isostructural rare earth metal–organic frameworks based on 1, 1'−butadiynebenzene−3, 3', 5, 5'−tetracarboxylate ligand were synthesized and structurally characterized in detail, and complex 1 is promising bifunctional luminescent probe for highly sensitive and selective sensing Fe3+ ions and TNP through luminescence quenching effect, complex 1 also exhibits good recyclability for detecting Fe3+ ions and TNP. The quenching mechanisms were studied as well. [ABSTRACT FROM AUTHOR]

Over the past few decades, photodynamic therapy (PDT) has evolved as a minimally invasive treatment modality offering precise control over cancer and various other diseases. To address inherent challenges associated with PDT, researchers have been exploring two promising avenues: the development of intelligent photosensitizers activated through light-induced energy transfers, charges, or electron transfers, and the disruption of photosensitive bonds. Moreover, there is a growing emphasis on the bioorthogonal delivery or activation of photosensitizers within tumors, enabling targeted deployment and activation of these intelligent photosensitive systems in specific tissues, thus achieving highly precise PDT. This concise review highlights advancements made over the last decade in the realm of light-activated or bioorthogonal photosensitizers, comparing their efficacy and shaping future directions in the advancement of photodynamic therapy. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) sensors with excellent performance play an important role in the safety application of H2 energy. Among current H2 detection technologies, surface acoustic wave (SAW) based H2 sensors attract more attention due to their features of high sensitivity, fast response, mico-nano scale and excellent stability, which was composed of a SAW sensing chip and sensing materials depositing along the acoustic wave propagation path, and utilizing the coupling mechanism of force-acoustic-electric multiple physical fields. Here we review the SAW H2 sensor, focusing on the H2 sensing materials, SAW sensing mechanisms, sensing devices, sensing circuits, and development status. And prospects were made for its development trends and challenges.

Abstract Optical microcavities have the ability to confine photons in small mode volumes for long periods of time, greatly enhancing light-matter interactions, and have become one of the research hotspots in international academia. In recent years, sensing applications in complex environments have inspired the development of multimode optical microcavity sensors. These multimode sensors can be used not only for multi-parameter detection but also to improve measurement precision. In this review, we introduce multimode sensing methods based on optical microcavities and present an overview of the multimode single/multi-parameter optical microcavities sensors. Expected further research activities are also put forward. Graphical abstract

The recent surge in using wearable personalized devices has made it increasingly important to flexible textile‐based sensors that can be worn comfortably and can sense various body strains. Among them, the knit‐based flexible strain sensors (KFSS) show growing promise for human activity monitoring applications due to its processing flexibility, low cost, wearing comfortability, large strain performance, and high elastic recovery rate. Herein, five sensing mechanisms of knitted flexible strain sensors containing contact resistance, length resistance, tunneling effect, micro‐crack propagation, and disconnection mechanism are summarized, which can be used on different human activity strain conditions, e.g., physiological activities and limb activities. The main fabrication approaches, including knitting techniques, post‐processing techniques, embroidery, and sewing techniques are discussed. Six crucial parameters with corresponding calculation formulas for evaluating sensing performance and review specific applications of KFSS for human limb activity and physiological activity monitoring in healthcare, motion tracking, safety protection, and human–machine interaction are also described. Finally, the tough challenges and prospects of KFSS with the aim of providing meaningful guidance and direction for future research are critically analyzed. [ABSTRACT FROM AUTHOR]

Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing. [ABSTRACT FROM AUTHOR]

Optical fiber biochemical sensing technology, as a cutting‐edge, multidisciplinary, and universal sensing technology, is gradually becoming the research focus in the field of biochemical sensing. They enjoy distinctive characteristics such as high cost‐effectiveness, flexibility, resistance to electromagnetic interference, and small size and can be used to detect biochemical analytes at ultra‐low concentrations with ultra‐low sample consumption, even when these biochemical analytes are in hard‐to‐reach environments. An aptamer is a DNA or RNA oligonucleotide fragment with a high affinity for the target selected from random sequences. Due to their advantages of simple synthesis, low cost, good stability, good specificity, and strong affinity, they are gradually becoming ideal recognition elements and may replace antibodies as next‐generation target receptors. Therefore, aptamers, as functional materials, are integrated into optical fiber sensors, which are called optical fiber aptasensors, providing new opportunities for the construction of high‐performance and intelligent biochemical sensors. This article aims to review the recent research progress of fiber‐optic aptamer biochemical sensors, with a focus on their sensing mechanisms and applications. Finally, based on the existing deficiencies of fiber‐optic aptamer biochemical sensors and practical requirements, their future development trends are briefly discussed. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) has been utilized in various optical applications, including biosensors. The SPR-based sensor is a gold standard for protein kinetic measurement due to its ultrasensitivity on the plasmonic metal surface. However, a slight change in the surface morphology, such as roughness or pattern, can significantly impact its performance. This study proposes a theoretical framework to explain sensing mechanisms and quantify sensing performance parameters of angular surface plasmon resonance detection for binding kinetic sensing at different levels of surface roughness. The theoretical investigation utilized two models, a protein layer coating on a rough plasmonic surface with and without sidewall coatings. The two models enable us to separate and quantify the enhancement factors due to the localized surface plasmon polaritons at sharp edges of the rough surfaces and the increased surface area for protein binding due to roughness. The Gaussian random surface technique was employed to create rough metal surfaces. Reflectance spectra and quantitative performance parameters were simulated and quantified using rigorous coupled-wave analysis and Monte Carlo simulation. These parameters include sensitivity, plasmonic dip position, intensity contrast, full width at half maximum, plasmonic angle, and figure of merit. Roughness can significantly impact the intensity measurement of binding kinetics, positively or negatively, depending on the roughness levels. Due to the increased scattering loss, a tradeoff between sensitivity and increased roughness leads to a widened plasmonic reflectance dip. Some roughness profiles can give a negative and enhanced sensitivity without broadening the SPR spectra. We also discuss how the improved sensitivity of rough surfaces is predominantly due to the localized surface wave, not the increased density of the binding domain. [ABSTRACT FROM AUTHOR]

Over the past few decades, photodynamic therapy (PDT) has evolved as a minimally invasive treatment modality offering precise control over cancer and various other diseases. To address inherent challenges associated with PDT, researchers have been exploring two promising avenues: the development of intelligent photosensitizers activated through light-induced energy transfers, charges, or electron transfers, and the disruption of photosensitive bonds. Moreover, there is a growing emphasis on the bioorthogonal delivery or activation of photosensitizers within tumors, enabling targeted deployment and activation of these intelligent photosensitive systems in specific tissues, thus achieving highly precise PDT. This concise review highlights advancements made over the last decade in the realm of light-activated or bioorthogonal photosensitizers, comparing their efficacy and shaping future directions in the advancement of photodynamic therapy.

To maintain human and environmental health, it is essential to detect toxic gases. Over the years, researchers have often focused on industrial waste gases like CO, NO2, H2S, and NH3. These hazardous gases can be detected by gas sensors.The conducting polymer, which has shown tremendous promise in room-temperature chemical gas detection due to the fact that its electrical conductivity may change when exposed to oxidative or reductive gas molecules, is one promising material for this sensor. Although in some circumstances, the decreased conductivity and significant attraction to volatile organic compounds and water molecules restrict sensitivity, stability, and gas selectivity, making them unsuitable for use as gas sensors. Inorganic sensitive materials provide various advantages in gas sensors, such as high sensitivity, rapid response to low-concentration analytes, a vast surface area, and changeable surface chemistry, which may supplement the sensing capabilities of conducting polymers. Along with their synergistic effects, there is a great deal of interest in combining inorganic sensitive materials with polymers for gas detection. This review focuses on the development of composite conducting polymers as gas-sensing materials. The implications of several factors affecting sensor performance, such as responsiveness, gas concentration, reaction time, and recovery time of conducting polymers, are highlighted. The function of inorganic nanomaterials in enhancing the gas-sensing performance of conducting polymers is discussed, as well as the development of conducting-inorganic composites including metal oxides, metal, and (carbon nanotube, and graphene. A comprehensive outlook on the topic of gas sensors containing conducting polymer-inorganic composites is delivered.

The development of appropriate luminophores for detecting nitroaromatic explosives is a crucial issue for our safety and security. In the past decade, astounding efforts have been made towards the development of phosphorescent iridium probes based on diverse sensing mechanisms for explosive detection. Phosphorescent iridium materials possess unique properties such as long-lived phosphorescence, high quantum efficiency, and modular syntheses that render them as suitable alternatives to organic dyes. According to the literature, many of the iridium molecular probes used to detect nitroaromatics are "turn-off" luminescence sensors. Thus, the review describes the current state-of-the-art, its accomplishments, unique challenges, and future directions. [ABSTRACT FROM AUTHOR]

A novel Cd-HCIA-3 coordination polymer was successfully synthesized, showcasing remarkable fluorescence properties and stability. Theoretical DFT calculations were used to predict the fluorescence sensing capabilities of Cd-HCIA-3. Fluorescence sensing experiment confirmed that Cd-HCIA-3 efficiently detects NB and ORN in aqueous solutions, validating the DFT predictions. [Display omitted] • The Cd-HCIA-3 with attractive fluorescence properties was synthesized by 5-H 3 CIA and 2,2′-bipy ligands. • ESP, PET, Δ E LUMO , pore size, and trap state were used as chemical descriptors to predict the fluorescence sensing properties of Cd-HCIA-3. • The intermolecular charge transfer is the main cause of fluorescence quenching. • The weak intermolecular interaction plays an important role in electron transfer process. • Cd-HCIA-3 can selectively detect NB and ORN in aqueous solutions. The improper utilization of nitrobenzene (NB) and ornidazole (ORN) has resulted in irreversible effects on the environment. By combining experimental investigation, density functional theory (DFT) calculations, and machine learning, an effective green strategy for detecting NB and ORN in aqueous solutions can be developed. In this study, a one-dimensional Cd-based coordination polymer (Cd-HCIA-3) was designed and synthesized using 5-((4-carboxybenzyl)oxy)isophthalic acid and rigid 2,2′-bipyridine under solvothermal reaction conditions. Cd-HCIA-3 exhibits excellent fluorescence properties and stability in aqueous solutions. DFT calculations were performed to predict the fluorescence sensing performance of Cd-HCIA-3, revealing that photoinduced electron transfer is the key mechanism for inducing fluorescence quenching in the presence of NB and ORN, with weak molecular interactions promoting electron transfer. Fluorescence sensing experiments were conducted to verify the DFT results, showing that Cd-HCIA-3 can selectively detect NB and ORN in aqueous solutions with limits of detection of 7.22 × 10−8 and 1.31 × 10−7 mol/L, respectively. This study's findings provide valuable insights into the design and synthesis of fluorescent coordination polymers for target analytes. [ABSTRACT FROM AUTHOR]

• Comprehensive review of advanced sensors for monitoring emerging contaminants in water. • Thorough evaluation of sensor performance and detection of emerging contaminants. • Strategic framework integrating nanotechnology for robust, deployable sensing solutions. Emerging contaminants in water represent long-term and unpredictable threats to both environmental and human health due to their persistence and bioaccumulation. Current research predominantly focuses on their removal rather than sustained monitoring. This review comprehensively investigates advanced sensor technologies for detecting these contaminants in water, critically evaluating biosensors, optical sensors, electrochemical sensors, and nanomaterial sensors. Elucidating the operational principles, performance metrics such as detection thresholds, and the pros and cons of their practical applications, the review addresses a significant research gap in environmental monitoring. Moreover, it enhances understanding of sensor effectiveness, which in turn guides researchers in selecting the right sensor types for various environmental scenarios. Furthermore, by emphasizing the integration of nanotechnology and the standardization of evaluation protocols, it promotes the development of robust, deployable sensing solutions. Ultimately, this leads to the proposal of a strategic framework aimed at significantly improving the detection capabilities of emerging contaminants and supporting the preservation of environmental health. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The form, design and application of CNTs based gas sensors. • Fully understanding of the sensing mechanism of CNTs based gas sensors. • The current development of CNTs based gas sensors. In the era of the Internet of Things, sensors are pivotal for a smart and interconnected future. Gas sensors, particularly those based on carbon nanotubes (CNTs), emerge as essential tools supporting environmental protection policies with their highly sensitive gas detection capabilities. This review highlights the recent strides in CNTs based gas sensors. It begins with outlining the CNT fundamental traits, establishing the groundworks for explaining their working principles and integrated manufacturing. The discussion proceeds to key parameters for evaluating gas sensor performance. Strengths-Weaknesses-Opportunities-Threats analysis showed that CNTs based gas sensors demonstrate promising potential in various applications, leveraging their exceptional responsiveness, sustainability, and integration capabilities, despite facing challenges in scalability and market competition. The review then delves into the research progress and sensing mechanisms of CNTs based gas sensors in environmental monitoring, industrial safety, and health care, showcasing their exceptional attributes like high sensitivity, fast response, and low power consumption. Finally, the future development of CNTs based gas sensors may focus on enhancing sensing performance, achieving miniaturization, integration and multifunctionality, standardizing measurement processes, as well as utilizing machine learning to improve sensor selectivity and stability. These advances aim to enhance reliability, broaden application scopes, facilitate commercialization, and meet the evolving needs of practical applications. [ABSTRACT FROM AUTHOR]

The utilization of clean hydrogen energy is becoming more feasible for the sustainable development of this society. Considering the safety issues in the hydrogen production, storage, and utilization, a sensitive hydrogen sensor for reliable detection is essential and highly important. Though various gas sensor devices are developed based on tin oxide, tungsten trioxide, or other oxides, the relatively high working temperature, unsatisfactory response time, and detection limitation still affect the extensive applications. In the current study, an amorphous tungsten trioxide (a‐WO3) layer is deposited on a phase‐change vanadium dioxide film to fabricate a phase transition controlled Pd/a‐WO3/VO2 hydrogen sensor for hydrogen detection. Results show that both the response time and sensitivity of the hydrogen sensor are improved greatly if increasing the working temperature over the transition temperature of VO2. Theoretical calculations also reveal that the charge transfer at VO2/a‐WO3 interface becomes more pronounced once the VO2 layer transforms to the metal state, which will affect the migration barrier of H atoms in a‐WO3 layer and thus improve the sensor performance. The current study not only realizes a hydrogen sensor with ultrahigh performance based on VO2 layer, but also provides some clues for designing other gas sensors with phase‐change material. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescence probe was designed for the determination of Al3+ by self-assembling of NH2-MIL-101(Fe) and [Ru(bpy)3]2+. Under the excitation wavelength of 360 nm, the NH2-MIL-101(Fe)@[Ru(bpy)3]2+ presented a dual-emitting luminescent property at 440 and 605 nm, respectively. In the presence of Al3+, the blue fluorescence of NH2-MIL-101(Fe)@[Ru(bpy)3]2+ at 440 nm was enhanced remarkably, while the red emission at 605 nm was almost not influenced. Therefore, taking the fluorescence at 440 nm as the report signal and 605 nm as the reference signal, quantitative determination was achieved for Al3+ concentration in the ranges 0.2–25 μM and 25–250 μM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 73 nM and 244 nM, respectively. The sensing mechanisms were studied by theoretical calculation and optical spectra. The analysis of real food samples confirmed the suitability of the proposed method. More importantly, portable fluorescent test papers were successfully manufactured to provide a strategy for visual, rapid, and on-site detection of Al3+. [ABSTRACT FROM AUTHOR]

Gas sensors that are based on metal oxides are extensively used to detect gaseous compounds in many different applications. One of the main tasks for improving the sensor performances is to understand the mechanism at the base of the sensing properties for each specific material. In this work, pure and mixed oxides were selected and synthesized in the form of nanometric powders. They were characterized by spectroscopic techniques, i.e., absorbance FT–IR and diffuse reflectance UV–Vis–NIR spectroscopies, to obtain information about the electronic properties and the type of defects that are involved at the root of the gas-sensing capabilities. The electrical characterization and the gas-sensing measurements were carried out on the related thick films. Finally, for each material, a description of the specific sensing mechanism is proposed by combining the characterization results. [ABSTRACT FROM AUTHOR]

Sulfur-containing gases, such as H 2 S and SO 2 , play significant roles in a multitude of biological processes affecting human life and health. Precise and efficient detection of these gases is therefore crucial for advancing one's understanding of their biological roles and developing effective diagnostic strategies. Fluorescent sensing offers a highly sensitive and versatile approach for detecting these gases. This Review examines the recent advances in the fluorescent detection of H 2 S and SO 2 , highlighting the key mechanisms involved in fluorescence signal transduction, including changes in intensity and wavelength shifts. The diverse array of probe molecules employed for this purpose, including those utilizing mechanisms such as nucleophilic reactions, Förster resonance energy transfer (FRET), and sulfur affinity interactions are explored. In additional to organic sensors, the focus of the Review is particularly directed toward quantum dot (QD) systems, emphasizing their tunable optical properties that hold immense potential for fluorescence sensing. Beyond the traditional III-V QDs, we delve into the emerging fluorescence sensors based on halide perovskite QDs, upconversion nanocrystals, and other novel materials. These advanced QD systems hold promise for the development of highly sensitive and cost-effective gas detectors, paving the way for significant advances in biomedical and environmental monitoring. This Review provides a comprehensive overview of the current state-of-the-art in QD-based fluorescence sensing of sulfur-containing gases and provides a multifaceted discussion comparing organic fluorescent sensors with QD sensors, highlighting the key challenges and opportunities for the integration of fluorescence sensing as it evolves. The Review aims to facilitate further research and development of innovative sensing platforms to enable more accurate and sensitive detection of these important gases.

Gas sensors are pivotal across industries, encompassing environmental monitoring, industrial safety, and healthcare. Recently, a surge in demand for low power gas sensors has emerged, driven by the huge need for applications in portable devices, wireless sensor networks, and the Internet of things (IoT). The practical realization of a densely interconnected sensor network demands gas sensors to have low power consumption for energy-efficient operation. This Perspective offers a comprehensive overview of the progress of low-power sensors for gas and volatile organic compound detection, with a keen focus on the interplay between sensing materials (including metal oxide semiconductors, metal-organic frameworks, and two-dimensional materials), sensor structures, and power consumption. The main gas sensing mechanisms are discussed, and we delve into the mechanisms for achieving low power consumption including material properties and sensor design. Furthermore, typical applications of low power gas sensors are also presented, including wearable technology, food safety, and environmental monitoring. The review will end by discussing some open questions and ongoing needs.

SnO2 hollow nanospheres (HNS) were synthesized by a hydrothermal method using carbon nanospheres, and Pd nanoparticles (NPs) were decorated by irradiation with an ultraviolet light to enhance its sensing performance. Six kinds of samples were synthesized followed by the amount of decorated Pd NPs to find optimum amount of Pd NPs showing the best hydrogen sensing response. The sensor fabricated with SnO2 HNS decorated with Pd NPs for 3 h exhibits a sensing response of 121 to 100 ppm hydrogen gas, whereas a sensor fabricated with bare SnO2 HNS exhibits a sensing response of 3.1. Furthermore, its hydrogen sensing selectivity is also improved as Pd NPs are decorated. It is difficult for SnO2 HNS to distinguish hydrogen gas from other gases including NO2 gas. However, as the Pd NPs are decorated with SnO2 HNS, their sensing responses to hydrogen gas drastically enhances, whereas the sensing responses to other gases do not. This enhanced hydrogen sensing performance of the Pd NP-decorated SnO2 HNS is related to the synergistic effects of the structural features of SnO2 HNS and the catalytic effect of Pd NPs. This study demonstrates the improved hydrogen sensing performance of Pd NP-decorated SnO2 HNS and discusses its enhanced sensing mechanisms.

Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing.

Homocysteine, cysteine, and glutathione are small molecules containing thiols that have important functions in several physiological and pathological processes in living beings. Homocysteine specifically, is a biological thiol linked with various kinds of diseases and conditions, including cancer, atherothrombosis, Alzheimer's disease, osteoporosis, mental disorders, etc. Consequently, real-time detection of Homocysteine holds significant value in preserving normal physiological conditions and monitoring the advancement of specific diseases. Therefore, advancing the development of fluorescent probes and elucidating their sensing mechanisms for homocysteine is paramount. This review highlights recent developments in fluorescent probes designed for detecting Homocysteine and explores their sensing mechanisms based on recent literature. This review discusses the development and application of homocysteine-specific probes in biomedical imaging. Additionally, our focus extends to the design strategies employed in creating fluorescent probe compounds and their derivatives, encompassing compounds such as coumarin, nitrobenzofurazan, cyanine, pyronin, BODIPY, and metal complexes. We also delve into the sensing mechanisms involved in the reaction of homocysteine, including the Michael addition reaction, Aromatic substitution rearrangement, Nucleophilic substitution rearrangement, cyclization reactions, metal complexes, and other reaction mechanisms. Discussions in all sections revolved around specific sensing mechanisms tailored for homocysteine, focusing on emission, color changes, detection limits, and their practical applications. • This review discussed the synthesis of probes for homocysteine detection. • We commented various methods for sensing and detecting homocysteine with the help of these probes. • We emphasize the use of Homocysteine-specific probes in the context of biomedical and bioimaging applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The preparation methods of MOF-enzyme/nanozyme composites are described in detail. • The unique functional roles of MOFs in the construction of MOF-enzyme/nanozyme composites are introduced. • The sensing mechanisms based on different catalytic reactions are summarized. • The challenges and prospects in preparation, development, and practical applications were discussed. The utility of non-homogeneous nanomaterials for the immobilization of enzymes has been demonstrated to enhance their catalytic performance. Alongside this, the advent of artificial nanozymes, carrying an intrinsic enzyme-like activity, has sparked widespread interest due to their potential as an alternative to natural enzymes, even earning a position among the top 10 emerging technologies in chemistry by the IUPAC in 2022. Metal–organic frameworks (MOFs), boasting unique qualities, have shown significant promise in the fields of catalysis and sensing applications. These unique properties make them a suitable candidate for the immobilization or modification of enzymes and nanozymes. In this review, we focus on MOF-enzyme/nanozyme composites and their applications in sensing. Our review summarizes the different immobilization strategies, highlights the functional roles of MOFs in the construction of MOF-enzyme/nanozyme composites, and provides a thorough and unique dissection of the sensing mechanisms in the detection of a variety of targets. We also discuss how to improve the catalytic activity and stability of MOF-enzyme/nanozyme composites and their sensing application prospects in clinical diagnosis, environmental monitoring, and food safety. [ABSTRACT FROM AUTHOR]

Water, although an important part of everyday life, is acts as one of the most significant contaminants in various applications such as biomedical monitoring, chemical production, petroleum-based fuel and food processing. In fact, the presence of water in other solvents is a huge concern. For the quantification of trace water content, different methods such as Karl-Fischer, electrochemical, nuclear magnetic resonance, chromatography, and thermogravimetric analysis have been used. Although every technique has its own benefit, each one suffers from several drawbacks that include high detection costs, lengthy procedures and specialized operations. Nowadays, the development of fluorescence-based chemical probes has become an exciting area of research for the quick and accurate estimation of water content in organic solvents. A variety of chemical processes such as hydrolysis reaction, metal ions promoted oxidation reaction, suppression of the –C═N isomerization, protonation and deprotonation reactions, and molecular aggregation have been well researched in the last few years for the fluorescent detection of trace water. These chemical processes eventually lead to different photophysical events such as aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), aggregation-caused quenching (ACQ), fluorescent resonance energy transfer (FRET), charge transfer, photo-induced electron transfer (PET), excited state intramolecular proton transfer (ESIPT) that are responsible for the detection. This review presents a summary of the fluorescence-based chemosensors reported in recent years. The design of water sensors, sensing mechanisms and their potential applications are reviewed and discussed. [Display omitted] • Detection of trace quantity of water is very important. • Fluorescent probes are developed for the facile and visual detection of water. • This review presents a summary of the fluorescence probes reported in the recent years. • Designing of probes, sensing mechanisms and their potential applications are reviewed and discussed. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) gas stands at the forefront of next-generation energy, offering unparalleled combustion efficiency with minimal carbon emissions. H 2 is also an important marker of many H 2 -related physiochemical processes in industries or medical practices (e.g., H 2 release in the thermal runaway of lithium-ion battery and the biodegradation of magnesium (Mg) implants in human body). The development of high-performance H 2 sensors is paramount for not only ensuring safety across various stages of H 2 production, storage, transportation, and utilization, and also monitoring many critical steps in industrial or medical processes. Among the multitude of sensing technologies, chemiresistive sensors, particularly those utilizing noble metals such as Pd and Pt, or metal-oxide-semiconductor (MOS) materials like SnO 2 and ZnO, have emerged as promising candidates, because these sensing materials can specifically and sensitively react with H 2 to result in their conductivity change allowing for the detection of H 2 gas. These materials offer not only exceptional performance metrics, but also cost-effectiveness, compact design, low power consumption, and ease of operation. In our review, for each type of chemiresistive sensors (noble-metal-based or MOS-based), we reviewed the fundamental sensing principles, and then summarized representative strategies that researchers developed in the last few years to improve specific aspects of sensing performance (e.g., sensitivity, selectivity, humidity tolerance, response time, hysteresis, etc.). In the summarization of each catalog of representative strategies, we emphasized why such strategies can improve specific sensing performance parameters. We hope that this review can help researchers gain valuable insights into this field and motivate them to explore and further advance the development of H 2 sensors for broader applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Plants are exposed to various environmental stresses. The sensing of environmental cues and the transduction of stress signals into intracellular signaling are initial events in the cellular signaling network. As a second messenger, Ca2+ links environmental stimuli to different biological processes, such as growth, physiology, and sensing of and response to stress. An increase in intracellular calcium concentrations ([Ca2+]i) is a common event in most stress-induced signal transduction pathways. In recent years, significant progress has been made in research related to the early events of stress signaling in plants, particularly in the identification of primary stress sensors. This review highlights current advances that are beginning to elucidate the mechanisms by which abiotic environmental cues are sensed via Ca2+ signals. Additionally, this review discusses important questions about the integration of the sensing of multiple stress conditions and subsequent signaling responses that need to be addressed in the future. [ABSTRACT FROM AUTHOR]

Over the past few decades, flexible sensors have been developed from the "electronic" level to the "iontronic" level, and gradually to the "ionic" level. Ionic flexible sensors (IFS) are one kind of advanced sensors that are based on the concept of ion migration. Compared to conventional electronic sensors, IFS can not only replicate the topological structures of human skin, but also are capable of achieving tactile perception functions similar to that of human skin, which provide effective tools and methods for narrowing the gap between conventional electronics and biological interfaces. In this review, the latest research and developments on several typical sensing mechanisms, compositions, structural design, and applications of IFS are comprehensively reviewed. Particularly, the development of novel ionic materials, structural designs, and biomimetic approaches has resulted in the development of a wide range of novel and exciting IFS, which can effectively sense pressure, strain, and humidity with high sensitivity and reliability, and exhibit self‐powered, self‐healing, biodegradability, and other properties of the human skin. Furthermore, the typical applications of IFS in artificial skin, human‐interactive technologies, wearable health monitors, and other related fields are reviewed. Finally, the perspectives on the current challenges and future directions of IFS are presented. [ABSTRACT FROM AUTHOR]

Plants are exposed to various environmental stresses. The sensing of environmental cues and the transduction of stress signals into intracellular signaling are initial events in the cellular signaling network. As a second messenger, Ca2+ links environmental stimuli to different biological processes, such as growth, physiology, and sensing of and response to stress. An increase in intracellular calcium concentrations ([Ca2+]i) is a common event in most stress-induced signal transduction pathways. In recent years, significant progress has been made in research related to the early events of stress signaling in plants, particularly in the identification of primary stress sensors. This review highlights current advances that are beginning to elucidate the mechanisms by which abiotic environmental cues are sensed via Ca2+ signals. Additionally, this review discusses important questions about the integration of the sensing of multiple stress conditions and subsequent signaling responses that need to be addressed in the future.

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

Surface plasmon resonance (SPR) has been utilized in various optical applications, including biosensors. The SPR-based sensor is a gold standard for protein kinetic measurement due to its ultrasensitivity on the plasmonic metal surface. However, a slight change in the surface morphology, such as roughness or pattern, can significantly impact its performance. This study proposes a theoretical framework to explain sensing mechanisms and quantify sensing performance parameters of angular surface plasmon resonance detection for binding kinetic sensing at different levels of surface roughness. The theoretical investigation utilized two models, a protein layer coating on a rough plasmonic surface with and without sidewall coatings. The two models enable us to separate and quantify the enhancement factors due to the localized surface plasmon polaritons at sharp edges of the rough surfaces and the increased surface area for protein binding due to roughness. The Gaussian random surface technique was employed to create rough metal surfaces. Reflectance spectra and quantitative performance parameters were simulated and quantified using rigorous coupled-wave analysis and Monte Carlo simulation. These parameters include sensitivity, plasmonic dip position, intensity contrast, full width at half maximum, plasmonic angle, and figure of merit. Roughness can significantly impact the intensity measurement of binding kinetics, positively or negatively, depending on the roughness levels. Due to the increased scattering loss, a tradeoff between sensitivity and increased roughness leads to a widened plasmonic reflectance dip. Some roughness profiles can give a negative and enhanced sensitivity without broadening the SPR spectra. We also discuss how the improved sensitivity of rough surfaces is predominantly due to the localized surface wave, not the increased density of the binding domain.

Gas sensors that are based on metal oxides are extensively used to detect gaseous compounds in many different applications. One of the main tasks for improving the sensor performances is to understand the mechanism at the base of the sensing properties for each specific material. In this work, pure and mixed oxides were selected and synthesized in the form of nanometric powders. They were characterized by spectroscopic techniques, i.e., absorbance FT–IR and diffuse reflectance UV–Vis–NIR spectroscopies, to obtain information about the electronic properties and the type of defects that are involved at the root of the gas-sensing capabilities. The electrical characterization and the gas-sensing measurements were carried out on the related thick films. Finally, for each material, a description of the specific sensing mechanism is proposed by combining the characterization results.

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

In recent years, considerable research efforts have been devoted to the development of wearable multi-functional sensing technology to fulfill the requirements of healthcare smart detection, and much progress has been achieved. Due to the appealing characteristics of flexibility, stretchability and long-term stability, the sensors have been used in a wide range of applications, such as respiration monitoring, pulse wave detection, gait pattern analysis, etc. Wearable sensors based on single mechanisms are usually capable of sensing only one physiological or motion signal. In order to measure, record and analyze comprehensive physical conditions, it is indispensable to explore the wearable sensors based on hybrid mechanisms and realize the integration of multiple smart functions. Herein, we have summarized various working mechanisms (resistive, capacitive, triboelectric, piezoelectric, thermo-electric, pyroelectric) and hybrid mechanisms that are incorporated into wearable sensors. More importantly, to make wearable sensors work persistently, it is meaningful to combine flexible power units and wearable sensors and form a self-powered system. This article also emphasizes the utility of self-powered wearable sensors from the perspective of mechanisms, and gives applications. Furthermore, we discuss the emerging materials and structures that are applied to achieve high sensitivity. In the end, we present perspectives on the outlooks of wearable multi-functional sensing technology.

Zinc oxide (ZnO) is a wide bandgap semiconductor material that has been widely explored for countless applications, including in biosensing. Among its interesting properties, its remarkable photoluminescence (PL), which typically exhibits an intense signal at room temperature (RT), arises as an extremely appealing alternative transduction approach due to the high sensitivity of its surface properties, providing high sensitivity and selectivity to the sensors relying on luminescence output. Therefore, even though not widely explored, in recent years some studies have been devoted to the use of the PL features of ZnO as an optical transducer for detection and quantification of specific analytes. Hence, in the present paper, we revised the works that have been published in the last few years concerning the use of ZnO nanostructures as the transducer element in different types of PL-based biosensors, namely enzymatic and immunosensors, towards the detection of analytes relevant for health and environment, like antibiotics, glucose, bacteria, virus or even tumor biomarkers. A comprehensive discussion on the possible physical mechanisms that rule the optical sensing response is also provided, as well as a warning regarding the effect that the buffer solution may play on the sensing experiments, as it was seen that the use of phosphate-containing solutions significantly affects the stability of the ZnO nanostructures, which may conduct to misleading interpretations of the sensing results and unreliable conclusions.

Heterostructured nanomaterials have been extensively studied for gas sensing applications because of their unique properties. In this study, we synthesized heterostructured nanomaterials consisting of p -type TeO 2 (p -TeO 2) NWs and discrete n -type ZnO (n -ZnO) nanoclusters (NCs) to detect NO 2 gas molecules. These nanomaterials were synthesized via thermal evaporation and atomic layer deposition (ALD) techniques and then systematically investigated for NO 2 sensing capabilities with regard to operating temperature, NO 2 response, response/recovery times, and selectivity. The successful formation of discrete n -ZnO NCs depending on ALD conditions was observed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and these nanomaterials were characterized by energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The NO 2 response of the p -TeO 2 NW sensors was considerably enhanced through the formation of discrete n -ZnO NCs. In addition, the synthesized sensors showed good NO 2 selectivity in comparison with interfering gases such as SO 2 , CO, and C 2 H 5 OH. Herein, the enhanced NO 2 sensing mechanisms of p -TeO 2 NWs by formation of discrete n -ZnO NCs will be discussed in detail. We also believe that the formation of discrete n -ZnO NCs is an effective way to enhance NO 2 sensing capabilities of p -TeO 2 NW-based gas sensors. [ABSTRACT FROM AUTHOR]

• A novel LMOF with 2-fold interpenetration constructed by solvothermal. • The fluorescent properties were investigated. • Selective and sensitive detection of Cu2+, Al3+ and Fe3+ ions. • The fluorescence sensing mechanism was analyzed. The quantitative research with high sensitivity of metal ions has been increasingly important due to the influence to the environment and human health. In this work, a new luminescent Cd-MOF has successfully been constructed by one-dimensional spiral chain-shaped CdO 6 clusters, H 2 O and 1-(4-carboxyphenyl)-5-methyl-4-oxo-1,4-dihydropyridazine-3-carboxylic acid ligands (H 2 (4-PDCA)), namely [Cd 2 (H 2 O)(4-PDCA) 2 ] n (SNUT-19), which were further characterized by single crystal X-ray diffraction, PXRD, FT-IR and TGA. Single crystal X-ray analysis revealed that SNUT-19 exhibits unique 1D [Cd–O–Cd] ∞ chain, further bridging by the ligand to form a three-dimensional (3D) structure with a 2-fold interpenetrated structure. SNUT-19 exhibits excellent water stability and good solid luminescence properties. In addition, the luminescence sensing experiments show that SNUT-19 as a fluorescent sensor for "turn on" and "turn off" luminescence sensitive detection of Cu2+, Al3+ and Fe3+ ions in aqueous media, which sensing mechanisms also have been investigated. A novel luminescent Cd-MOF has successfully been constructed by 1-(4-carboxyphenyl)-5-methyl-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (H 2 (4-PDCA)), namely [Cd 2 (H 2 O)(4-PDCA) 2 ] n (SNUT-19), which were further characterized by single crystal X-ray diffraction, PXRD, FT-IR and TGA. Single crystal X-ray analysis revealed that SNUT-19 exhibits unique 1D [Cd–O–Cd] ∞ chain, further bridging by the ligand to form a three-dimensional (3D) structure with a 2-fold interpenetrated structure. SNUT-19 exhibits excellent water stability and good solid luminescence properties. In addition, the luminescence sensing experiments show that SNUT-19 as a fluorescent sensor for "turn on" and "turn off" luminescence sensitive detection of Cu2+, Al3+ and Fe3+ ions in aqueous media, which sensing mechanisms also have been investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

The surface and electronic engineering of the 2D SnS 2 have recently attracted substantial courtesies in various applications due to the abundant active oxygen sites and high transport properties because of electronic modulation. Herein, we reviewed the recent signs of progress in the morphological, structural, elemental properties, and gas-detection characteristics of the two-dimensional SnS 2. Furthermore, it also offers information on recent advancements and developments of various types of gas sensors prepared using the SnS 2 and its heterostructures. Numerous influential gas recognition parameters have also been discussed. The gas sensing mechanisms are also discussed on NH 3 , NO 2 , H 2 S, and VOCs to explore the interactions of the test gas with the sensor surface, elucidating the crucial role of active surface and electronic features of SnS 2 and its heterostructures on the rapid response and recovery profiles. Besides, it provides insight into the adsorption/desorption chemistry on the sensor's surface and eco-friendly environment. However, it is found that there is still vast scope for SnS 2 sensors to detect several other gases, which are still not studied and reported in the literature. Therefore, it opens up a new opportunity to develop various types of gas sensors to discriminate the particular gas at optimum working temperature and concentrations. Finally, the review clinches with the future perspectives and positions of the SnS 2 -based gas sensors. [Display omitted] [ABSTRACT FROM AUTHOR]