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This manuscript offers a concise overview of paper microfluidics, emphasizing its sustainable sensing applications in healthcare, environmental monitoring, and food safety. Researchers have developed innovative sensing platforms for detecting pathogens, pollutants, and contaminants by leveraging the paper's unique properties, such as biodegradability and affordability. These portable, low-cost sensors facilitate rapid diagnostics and on-site analysis, making them invaluable tools for resource-limited settings. This review discusses the fabrication techniques, principles, and applications of paper microfluidics, showcasing its potential to address pressing challenges and enhance human health and environmental sustainability. [ABSTRACT FROM AUTHOR]

This manuscript offers a concise overview of paper microfluidics, emphasizing its sustainable sensing applications in healthcare, environmental monitoring, and food safety. Researchers have developed innovative sensing platforms for detecting pathogens, pollutants, and contaminants by leveraging the paper’s unique properties, such as biodegradability and affordability. These portable, low-cost sensors facilitate rapid diagnostics and on-site analysis, making them invaluable tools for resource-limited settings. This review discusses the fabrication techniques, principles, and applications of paper microfluidics, showcasing its potential to address pressing challenges and enhance human health and environmental sustainability.

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit.

The possibility of analyzing the general and functional diversity of the ecosystem is considered, as is unambiguous interpretation of the results obtained based on our work experience and previously obtained data. The prospects for studying small mammals without removal from the wild are discussed. We discuss distinguishing in a sample the resident component, which makes it possible to characterize local resource flows, and the nonresident component, dependent on the state of the territory as a whole. A description of the capture–mark–recapture protocol, methods for assessing spatial activity, calculating the density of the resident population per unit area, and the completeness of species richness estimate is provided. The estimates of animal numbers per unit of trapping effort in pooled sample, the population density of residents, and the index of the nonresident flow are compared. The possibility of analyzing the resource flows in "historical," "novel," and "hybrid" ecosystems, as well as using data to analyze the resilience of the ecosystem and detect the threshold point, is considered. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel filter paper patterning method based on parylene C. • A paper-based colorimetric sensor for detection of Al (III) using a smartphone platform. • The detection range of the sensor for Al (III) detection is 0.05 to 10 mg/mL. The detection limit is 0.05 mg/mL. • The assembled paper-based smartphone sensor platform has the potential to detect other biochemical molecules. The paper-based analytical platforms have been applied in biochemical detection and environmental monitoring due to their low cost and easy operation. Despite their advantages, the complexity of fabrication has limited their further application. Here, a simple and innovative approach using parylene C, a material commonly used in semiconductors, is reported to fabricate paper-based chips and construct a point-of-care testing (POCT) platform through smartphones. Parylene C is deposited on the filter paper through a polydimethylsiloxane (PDMS) clamp and forms a hydrophobic barrier. A three-channel paper-based chip was utilized to detect aluminum (Al) ions on a smartphone platform by the chromogenic method. The color change after Al3+ detection is represented with △E which was photographed and calculated by app on smartphone. The detection limit is 0.05 mg/L and the detection range is from 0.05 mg/L to 10 mg/L which indicates the application potential in the field of biochemical detection. This new paper-based sensing method and smartphone-based portable detection platform are simple, low-cost, fast, and highly sensitive, and provides a potential application for on-site, visual detection of ions and even other substances. [ABSTRACT FROM AUTHOR]

Printable biosensors have gained numerous exciting advancements towards downstream applications in fundamental biomedical research, healthcare, food safety, environmental monitoring and governance, and to name a few. Particularly, paper-based printable biosensors have gained rising popularity in providing affordable platforms due to their merits, such as cost-effective, accurate, simple, and efficient detection of diseases for clinical diagnosis. In addition to advantages and opportunities in point-of-care detection, printable biosensors are also facing challenges. Herein, this review aims to provide a systematic summary of the development of printable biosensors, with a special focus on paper-based printable biosensors. Different types of substrates for printable biosensors are highlighted with a focus on paper substrates which have superior properties like low-cost, simple, flexible, lightweight, recyclable, etc. In addition, current printing technologies to fabricate paper-based sensors, including wax printing, photolithography, screen printing, inkjet printing, and laser printing summarize, are discussed, together with strategies for biomolecular fabrication on substrates and transducers. Finally, we also discuss the challenges and possible future perspectives, hoping to provide researchers and clinicians with informative insights into paper-based printable biosensors for smart and effective point-of-care detection. [ABSTRACT FROM AUTHOR]

Pulp and paper industries emit various odorous gases during the pulp production and paper-making phase, which are unpleasant and have harmful effects on the human body. The working staffs are continuously exposed to these gases and develop various health issues. Hence, regular monitoring and analysis of such gases are necessary to avoid any sudden high concentration exposure and to prevent adverse health effects on the staff. An electronic nose (EN) has an array of gas sensors with an alert system for early detection of gases. Various ENs have been developed for varying applications till date. The detailed knowledge of the sensors used, their sensitivity and technology is helpful in development of any EN. The objective of this study is to comprehensively review various developed ENs with respect to their gas sensing and pattern recognition (PR) technologies. The information on gases released from pulp and paper industries is also compiled. The evolution of EN technology, its various applications, challenges in developing EN and its utility in safeguarding the industrial workers' life have been described. Further, gap analysis among previously developed EN, contemporary EN and wireless sensor network (WSN) is elaborated. It will facilitate future researchers for better selection of sensors and PR technologies while developing EN. The commonly used sensing technologies are described with their advantages, disadvantages and working principles. Metal oxide semiconductor (MOS) gas sensor and ANN algorithm show better result and hence recommended in the development of EN, whereas ZigBee protocol has been widely used for WSN. [ABSTRACT FROM AUTHOR]

In this paper, the behavior of the Bi-Material Cantilever (B-MaC) response deflection upon fluidic loading was experimentally studied and modeled for bilayer strips. A B-MaC consists of a strip of paper adhered to a strip of tape. When fluid is introduced, the paper expands while the tape does not, which causes the structure to bend due to strain mismatch, similar to the thermal loading of bi-metal thermostats. The main novelty of the paper-based bilayer cantilevers is the mechanical properties of two different types of material layers, a top layer of sensing paper and a bottom layer of actuating tape, to create a structure that can respond to moisture changes. When the sensing layer absorbs moisture, it causes the bilayer cantilever to bend or curl due to the differential swelling between the two layers. The portion of the paper strip that gets wet forms an arc, and as the fluid advances and fully wets the B-MaC, the entire B-MaC assumes the shape of the initial arc. This study showed that paper with higher hygroscopic expansion forms an arc with a smaller radius of curvature, whereas thicker tape with a higher Young's modulus forms an arc with a larger radius of curvature. The results showed that the theoretical modeling could accurately predict the behavior of the bilayer strips. The significance of paper-based bilayer cantilevers lies in their potential applications in various fields, such as biomedicine, and environmental monitoring. In summary, the novelty and significance of paper-based bilayer cantilevers lie in their unique combination of sensing and actuating capabilities using a low-cost and environmentally friendly material. [ABSTRACT FROM AUTHOR]

The use of paper as a multifunctional material in electrochemical sensing has been intensively explored over the last decade. The combination among different kinds of paper as well as their coupling with different electrochemical cell configurations have been demonstrated, disclosing innovative sensing performances and features that are still to be fully investigated. This ongoing research has found applications in a variety of fields, including the biomedical, agri-food, security, and environmental ones, thanks to the high versatility and adaptability of the paper material. In this review, we report a critical and comparative analysis of electrochemical devices based on paper published within 2010–2021 and applied for the detection of pollutants of environmental interest in fresh water, seawater, and other real environmental matrices. Several paper types, from common office paper to Whatman filter paper with different filtering grades, were proved to be useful in this field. In detail, the multifarious roles played by the paper are discussed, highlighting how the paper can be a suitable material for electrochemical sensing while being capable of simplifying the measurement of complex real matrices or realizing programmable origami-like structures. Among the most important pollutants, a special focus is dedicated to the emerging pollutants. Furthermore, the unique advantages achieved by the paper have been analyzed and highlighted, reporting the future perspectives regarding the use of this surprising material.

Sensor arrays, which draw inspiration from the mammalian olfactory system, are fundamental concepts in high-throughput analysis based on pattern recognition. Although numerous optical sensor arrays for various targets in aqueous media have demonstrated their diverse applications in a wide range of research fields, practical device platforms for on-site analysis have not been satisfactorily established. The significant limitations of these sensor arrays lie in their solution-based platforms, which require stationary spectrophotometers to record the optical responses in chemical sensing. To address this, this review focuses on paper substrates as device components for solid-state sensor arrays. Paper-based sensor arrays (PSADs) embedded with multiple detection sites having cross-reactivity allow rapid and simultaneous chemical sensing using portable recording apparatuses and powerful data-processing techniques. The applicability of office printing technologies has promoted the realization of PSADs in real-world scenarios, including environmental monitoring, healthcare diagnostics, food safety, and other relevant fields. In this review, we discuss the methodologies of device fabrication and imaging analysis technologies for pattern recognition-driven chemical sensing in aqueous media. [Display omitted] • Cross-reactive sensors are applied to paper-based arrays for simultaneous detection. • Portable digital recorders can be used for detecting various responses. • Imaging analysis techniques can accelerate accurate data processing. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based point-of-care assays are a highly valuable technology with many promising applications in public health and environmental monitoring. High-sensitivity detection of certain trace substances is one of the critical important considerations for practical usage of microfluidic point-of-care techniques. Over the past decade, luminescence nanoprobes have been increasingly emerged as powerful toolboxes to achieve exceptional sensitivity and low detection limits for many chemical sensors. In this Review, we provide an overview of the fundamental principles underlying paper-based microfluidic point-of-care detection. We highlight various luminescence nanoprobes, including nano-diamonds, upconversion luminescent nanoparticles, inorganic quantum dots, and carbon dots, along with their corresponding sensing mechanisms. In subsequent sections, we emphasize the requisite utilization of specialized readout equipment for the effective implementation of fluorescence detection. Moreover, we summarize key microfluidic design strategies capable of achieving enhanced precision in the detection processes. We also discuss future research directions and the main challenges to be addressed for fluorescence nanoprobes-inspired paper-based microfluidic point-of-care technology. • Microfluidic point-of-care paper-based Luminescence assays. • Luminescence nanoprobes and corresponding mechanism. • Portable devices for signal readout and diagnosis. [ABSTRACT FROM AUTHOR]

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit. [ABSTRACT FROM AUTHOR]

An essential requirement for colorimetric paper-sensor is to allow the target analytes (heavy metal ions) to access the chromophore while maintaining strong chromophore immobilization on the porous substrate surface. This work evaluates the selection of sensitive chromophores (dithizone, 1-(2-pyridylazo) 2-naphthol and 4-(2-pyridylazo)-resorcinol) and their immobilization strategies on paper sensors. Dithizone (DTz) are capable of producing a significant color transition at unadjusted pH, observed by UV–Vis absorption spectroscopy and visible recognition. After immobilizing DTz on a paper substrate (cellulose acetate/chitosan substrate), the DTz-paper sensor showed a distinctive color change from blue-green to peach-pink upon reaction with Pb2+ ions, and the color intensity was proportional to the metal concentration. Quantitative analysis using RGB (R:Red; G:Green; B:Blue) plots showed that increasing DTz concentration on the CA/CS paper sensor increases the difference in total color intensity (∆IT) and the difference in red code intensity (∆IR). This is due to the formation of more DTz-Pb2+ complexes on the CA/CS paper substrate. The CA/CS paper strips immobilized with 100 ppm DTz showed practical potential for rapid detection of heavy metal ions. The DTz-CA/CS paper sensor showed significant color change when detecting spiked heavy metals ions (0.1 ppm Pb2+, 2.0 ppm Zn2+, and 0.2 ppm Cu2+) in river water samples that prepared at the maximum permissible limit for industrial effluent in Malaysia. [ABSTRACT FROM AUTHOR]

Since the monumental work conducted by Whitesides et al. in 2007, research and development of paper-based microfluidics has been widely carried out, with its applications ranging from chemical and biological detection and analysis, to environmental monitoring and food-safety inspection. Paper-based microfluidics possesses several competitive advantages over other substrate materials, such as being simple, inexpensive, power-free for fluid transport, lightweight, biodegradable, biocompatible, good for colorimetric tests, flammable for easy disposal of used paper-based diagnostic devices by incineration, and being chemically modifiable. Myriad methods have been demonstrated to fabricate paper-based microfluidics, such as solid wax printing, cutting, photolithography, microembossing, etc. In this study, fabrication of paper-based microfluidics was demonstrated by spray on the printed paper. Different from the normally used filter papers, printing paper, which is much more accessible and cheaper, was utilized as the substrate material. The toner was intended to serve as the mask and the patterned hydrophobic barrier was formed after spray and heating. The processing parameters such as toner coverage on the printing paper, properties of the hydrophobic spray, surface properties of the paper, and curing temperature and time were systematically investigated. It was found that, after repetitive printing four times, the toner was able to prevent the hydrophobic spray (the mixture of PDMS and ethyl acetate) from wicking through the printing paper. The overall processing time for fabrication of paper-based microfluidic chips was less than 10 min and the technique is potentially scalable. Glucose detection was conducted using the microfluidic paper-based analytical devices (µPADs) as fabricated and a linear relationship was obtained between 1 and 10 mM. [ABSTRACT FROM AUTHOR]

The sustainable goal of technological advancement is to go from lab to site through the development of a sensitive, specific and portable sensor for pollution monitoring. Herein, we report a completely portable colorimetric prototype device for the selective monitoring of lead (Pb) pollution, mainly in air, which relies on a new aspect of analysing the colorimetric assays on paper strips by the direct measurement of the retroreflective information, other than the available tedious image analysis methods. Our indigenously developed citrate-functionalized silver nanoparticles (AgNPs) embedded in cellulose paper strips showed significant localized surface plasmonic resonance (LSPR) peaks in the blue region and with the increase in the Pb concentration, the LSPR band in the blue region decreased and a new peak appeared in the green region of the electromagnetic spectrum due to the formation of larger aggregates. The prototype device monitored these spectral changes and accordingly gave the Pb content present in the sample. In this work, we made the sample under study by the acid digestion of one of the widely present air-suspended particulates, i.e., PbO2. The prototype device is a suitable fielddeployable technique for environmental Pb sensing and will open up new perspectives for future advancement in low-cost paper-based sensing. [ABSTRACT FROM AUTHOR]

Objectives Paper dust has previously been linked to adverse health effects. However, a comprehensive dataset of paper dust exposures does not appear to have been published previously. Our study was intended to address this need by describing a large dataset of measurements made in Swedish soft tissue paper mills. Methods We compiled personal and area total dust exposure measurements collected from a range of operations by our research staff at four soft tissue paper mills in Sweden. We also compiled measurements made by the occupational health staff at each mill and the Swedish Work Environment Authority. We analyzed these measurements to describe patterns and trends in exposures and used mixed-effects regression models to identify measurement characteristics that predicted exposure levels. Results We compiled 1578 measurements from 1971 to 2009, of which 1026 (65%) were personal samples. Statistically significant differences were found between measurements made by research, mill, and Swedish Work Environment Authority staff, as well as between personal and area measurements. The measurement data suggest that, beginning in the 1980s, exposures declined at three of the four mills, but that overexposures were still common at the end of the period. Papermaking and converting operations had the highest observed dust exposures. One mill had significantly lower exposures than the others. Type of measurement (personal versus area) and source of measurement (research staff, company, or regulatory agency) were not significant predictors of measured total dust exposure after controlling for mill, operation, and time. Conclusions Our analysis of measured paper dust exposures may be useful for historical and contemporary exposure assessment in our own and other epidemiological studies. We have identified specific characteristics (i.e. papermaking operations and mill) and time trends that are important data features to consider, and documented continuing overexposure situations. Our results highlight the ongoing need for application of exposure controls to reduce paper dust exposures in the soft tissue paper industry. [ABSTRACT FROM AUTHOR]

Point-of-care testing (POCT) technology is urgently required owing to the prevalence of the Internet of Things and portable electronics. In light of the attractive properties of low background and high sensitivity caused by the complete separation of excitation source and detection signal, the paper-based photoelectrochemical (PEC) sensors, featured with fast in analysis, disposable and environmental-friendly have become one of the most promising strategies in POCT. Therefore, in this review, the latest advances and principal issues in the design and fabrication of portable paper-based PEC sensors for POCT are systematically discussed. Primarily, the flexible electronic devices that can be constructed by paper and the reasons why they can be used in PEC sensors are expounded. Afterwards, the photosensitive materials involved in paper-based PEC sensor and the signal amplification strategies are emphatically introduced. Subsequently, the application of paper-based PEC sensors in medical diagnosis, environmental monitoring and food safety are further discussed. Finally, the main opportunities and challenges of paper-based PEC sensing platforms for POCT are briefly summarized. It provides a distinct perspective for researchers to construct paper-based PEC sensors with portable and cost-effective, hoping to enlighten the fast development of POCT soon after, as well as benefit human society. • The merits of functionalized paper for PEC sensor are introduced. • Photosensitive material and signal amplification strategy of paper-based PEC sensor are discussed. • The application of paper-based PEC sensor in the field of POCT is highlighted. • The limitations and challenges of paper-based PEC sensor are summarized. [ABSTRACT FROM AUTHOR]

Low-cost paper-based analytical devices are the latest generation of portable lab-on-chip designs that offers an innovative platform for the on/off-site analysis (biosensing) of target analytes, especially in rural and remote areas. Recently, microfluidic paper-based analytical devices (μPADs) have attained significant recognition owing to their exciting fundamental features such as: ease of fabrication, rapid operation, and precise interpretations. The incorporation of enzymes with paper-based analytical devices significantly improves analytical performance while exhibiting excellent chemical and storage stability. In addition to that, these devices are highly compact, portable, easy-to-use, and do not require any additional sophisticated equipment for the detection and quantification of target analytes. This review provides a holistic insight into design, fabrication, and enzyme immobilization strategies for the development of enzyme-μPADs, which enables them to be widely implemented for in-field analysis. It also highlights the recent application of enzyme-μPADs in the area of: biomedical, food safety, and environmental monitoring while exploring the mechanisms of detection involved. Further, in order to improve the accuracy of analysis, researchers have designed a smartphone-based scanning tool for multi-variant point-of-care devices, which is summarized in the latter part of the review. Finally, the future perspectives and outlook of major challenges associated with enzyme-μPADs are discussed with their possible solutions. The development of enzyme integrated μPADs will open a new avenue as an exceptional analytical tool to explore various applications. Enzyme embedded paper-based analytical devices are a revolution in the field of biosensing. The design, fabrication, and enzyme immobilization on μPADs have been comprehensively discussed. The application of enzyme-μPADs food safety, environmental monitoring, and clinical diagnostic have been reviewed. Smartphones can be used as an on-site, user-friendly, and compact next-gen scanning tool for biosensing. [ABSTRACT FROM AUTHOR]

Accurate and up‐to‐date biodiversity forecasts enable robust planning for environmental management and conservation of landscapes under a wide range of uses. Future predictions of the species composition of ecological communities complement more frequently reported species richness estimates to better characterize the different dimensions of biodiversity. The models that make community composition forecasts are calibrated with data on species' geographic patterns for the present, which may not be good proxies for future patterns. The future establishment of novel communities represents data on species interactions unaccounted for by these models. However, detecting them in a systematic way presents challenges due to the lack of monitoring data for landscapes with high environmental turnover, where such communities are likely to establish. Here, we propose lightweight monitoring over both ecological and anthropogenic disturbance gradients using passive sensors (i.e., those that operate continuously without much human input) to detect novel communities with the aim of updating models that make community composition forecasts. Monitoring over these two gradients should maximize detection of novel communities and improve understanding of relationships between community composition and environmental change. Further, barriers regarding cost and effort are reduced by using relatively few sensors requiring minimal upkeep. Ongoing updates to community composition forecasts based on novel community data and better understanding of the associated uncertainty should improve future decision‐making for both resource management and conservation efforts. [ABSTRACT FROM AUTHOR]

The recognition and detection of metal ions present in biological and environmental samples have attracted great attention in recent years. Various analytical techniques are used to detect metal ions. Among these, the fluorescence technique is among the emerging methods because of its simplicity, selectivity, and applicability to bioimaging. Thus, this review particularly explores paper-based fluorescence chemosensors involved in metal ion detection. Significantly, the first section addresses relevant research on metal ion detection involving various techniques. In the second section, several sensing strategies such as photoinduced electron transfer, fluorescence resonance energy transfer, intramolecular charge transfer, chelation enhanced fluorescence, excited-state intramolecular proton transfer, and aggregation-induced emission for the detection of target metal ions (aluminum, copper, iron, lead, mercury, and zinc) are investigated. The third section particularly discusses the role of fluorescence sensor materials (e.g., fluorescein, rhodamine, naphthalimide, BODIPY, carbon dots, quantum dots) involved in the detection processes and their advantages and limitations. Overall, this article reviews 90 research articles on paper-based fluorescence chemosensors for metal ion detection published until 2021. [ABSTRACT FROM AUTHOR]

Pathogens cause various infectious diseases and high morbidity and mortality which is a global public health threat. The highly sensitive and specific detection is of significant importance for the effective treatment and intervention to minimise the impact. However, conventional detection methods including culture and molecular method gravely depend on expensive equipment and well-trained skilled personnel, limiting in the laboratory. It remains challenging to adapt in resource-limiting areas, e.g., low and middle-income countries (LMICs). To this end, low-cost, rapid, and sensitive detection tools with the capability of field testing e.g., a portable device for identification and quantification of pathogens, has attracted increasing attentions. Recently, paper-based microfluidic analytical devices (μPADs) have shown a promising tool for rapid and on-site diagnosis, providing a cost-effective and sensitive analytical approach for pathogens detection. The fast turn-round data collection may also contribute to better understanding of the risks and insights on mitigation method. In this paper, critical developments of μPADs for in-field detection of pathogens both for clinical diagnostics and environmental surveillance are reviewed. The future development, and challenges of μPADs for rapid and onsite detection of pathogens are discussed, including using the cross-disciplinary development with, emerging techniques such as deep learning and Internet of Things (IoT). [Display omitted] • The state-of-the-art on μPAD is critically reviewed. • μPAD enables onsite detections of biochemical markers from molecules to organisms. • Insights is provided highlighting on multidisciplinary aspects. [ABSTRACT FROM AUTHOR]

Dissolved sulfide tends to species transformation and loss upon leaving the matrix, thus the development of a practical on-site determination of sulfide is crucial for environmental monitoring and human health. In this work, a novel paper-based ratiometric fluorescence sensor was developed for the field analysis of sulfide, which system was constructed by the inner filter effect (IFE) of CdS quantum dots (QDs) toward carbon dots (C-dots). Instead of an aqueous phase system, the conversion of sulfide to its hydride would induce the in-situ formation of CdS QDs on the paper, which acted as an energy acceptor to quench the emission of C-dots, leading to a variation of ratiometric fluorescence from blue to yellow with the increasing concentration of sulfide. Moreover, we proposed a smartphone-based fluorescence capture device integrated with a programmed Python program, accomplishing both color recognition and accurate detection of sulfide. Under the optimal condition, this ratiometric fluorescence sensor allowed for the on-site analysis of sulfide with a limit of detection of 0.05 μM. The accuracy of the sensor was validated via the successful field analysis of environmental water samples with satisfactory recoveries. Compared to other fluorescence methods used for sulfide analysis, this developed system retains the advantages of label-free, low-cost, ease of operation, and miniaturization, showing great potential for the measurement of sulfide on-site, as well as environmental monitoring. [Display omitted] • A paper-based fluorescence sensor was developed for the field analysis of sulfide. • Sulfide induced the IFE between C-dots and CdS QDs and caused fluorescence change. • The portable device for sulfide analysis is low-cost and easy to operate. • The developed system shows great potential for the measurement of sulfide on-site. [ABSTRACT FROM AUTHOR]

Here, an inkjet printed paper electrode (PPE) decorated with graphene (Gr)-silver (Ag) nanocomposite was exploited as an electrochemical sensing probe for analysis of 4-nitrophenol (4-NP) in environmental water samples. In this work, 4% Gr-Ag nanocomposite ink (NI) was prepared in ethanol, ethylene glycol, and glycerol in the ratio of 50:45:5, which possess surface tension and viscosity of 36 mN m−1 and 11 mPa s, respectively. The office inkjet printer was employed to print formulated Gr-Ag NI on digital photo paper, followed by sintered at 200 °C for 30 min to make effective conducting tracks for the sensing of 4-NP. Gr-Ag NI-based PPE was used as a working electrode in cyclic voltammetry. The working principle of detection is based on the electrocatalytic reduction process of 4-NP on the electrode surface. A good linearity range of 3.125–100 μM was observed, achieving a detection limit of 2.7 μM to measure 4-NP. Thus, the developed PPE holds considerable potential and offers an economical, biodegradable, and user-friendly sensor for future applications in the monitoring of 4-NP in environmental water samples. [Display omitted] • Printed paper electrode (PPE) with graphene (Gr)-silver (Ag) was used as electrochemical sensing for 4-nitrophenol (4-NP). • Inkjet printer was employed to print formulated Gr-Ag NI on photo paper and sintered at 200 °C for 30 min to make electrode. • Gr-Ag/PPE was used as a working electrode in cyclic voltammetry for 4-NP determination. • Gr-Ag/PPE provides a low cost, decomposable, and user-friendly sensor for monitoring of 4-NP in environmental water sample. [ABSTRACT FROM AUTHOR]

Microfluidic devices have emerged as advantageous tools for detecting environmental contaminants due to their portability, ease of use, cost-effectiveness, and rapid response capabilities. These devices have wide-ranging applications in environmental monitoring of air, water, and soil matrices, and have also been applied to agricultural monitoring. Although several previous reviews have explored microfluidic devices' utility, this paper presents an up-to-date account of the latest advancements in this field for environmental monitoring, looking back at the past five years. In this review, we discuss devices for prominent contaminants such as heavy metals, pesticides, nutrients, microorganisms, per- and polyfluoroalkyl substances (PFAS), etc. We cover numerous detection methods (electrochemical, colorimetric, fluorescent, etc.) and critically assess the current state of microfluidic devices for environmental monitoring, highlighting both their successes and limitations. Moreover, we propose potential strategies to mitigate these limitations and offer valuable insights into future research and development directions. [ABSTRACT FROM AUTHOR]

The development of cost-effective sensing system for Hg2+ quantitation is highly demanded for environmental monitoring. In this work, we reported an on-site, rapid and portable smartphone-based Hg2+ sensing system integrating coumarin-modified paper as a probe and smartphone readout device as a processing platform. For fluorescent sensing of Hg2+, the modified paper was fabricated by chemically grafting a coumarin-based probe N-((7-hydroxy-coumarin-3-yl)carbamothioyl)acetamide (HCCA) onto paper, and its physicochemical properties and sensing performance were characterized by elemental analysis, FTIR, XPS, SEM, and fluorescence spectral analysis. The modified paper displayed high selectivity and sensitivity for Hg2+, accompanied with a distinct fluorescence color change. For portable detection of the fluorescent sensors, a smartphone readout device was designed, consisting of a removable 3D-printed hardware device and an application. Remarkably, the smartphone readout device in cooperation with the modified paper is highly selective and sensitive to Hg2+ with the limit of detection (LOD) of 0.46 ppb, which avoids the requirement of sophisticated equipment and complex operation. The cost-effective sensing system based on smartphone shows a great potential for monitoring of Hg2+ in environmental water. [Display omitted] • A coumarin-modified paper was fabricated by chemical grafting. • The modified paper showed good fluorescent sensing performance for Hg2+. • A smartphone readout device was designed containing hardware and software. • The smartphone-based sensing system could quantify Hg2+ reliably and portably. [ABSTRACT FROM AUTHOR]

Developing an inexpensive, sensitive, and point-of-use biosensor for pesticide detection is becoming an important area in sensing. Such sensors can be used in food packaging, agricultural fields, and environmental monitoring of pesticides. The present investigation has developed a zinc oxide (ZnO)-based biosensor on porous, flexible substrates such as carbon paper and carbon cloth to detect organophosphates such as paraoxon (OP). Here, the influence of morphology and underlying substrate on biosensor performance was studied. The biosensors were fabricated by immobilizing the acetylcholinesterase (AChE) enzyme on ZnO, which is directly grown on the flexible substrates. The ZnO biosensors fabricated on the carbon cloth demonstrated good performance with the detection limit of OP in the range of 0.5 nM–5 µM, higher sensitivity, and greater stability. [ABSTRACT FROM AUTHOR]

The rapid urbanization and industrialization have caused a significant increase in environmental pollution, especially in air quality. This paper introduces an IoT-based environmental monitoring system to address these issues. Using state-of-the-art IoT technology, the system deploys sensors in key locations to continuously collect data on air quality indicators like Particulate Matter (PM), Carbon Monoxide (CO), and Ozone (O3). The collected data is wirelessly transmitted to a central server for processing and analysis. The system provides real-time and historical data through a user-friendly interface, enabling users to monitor current conditions, identify trends, and identify potential pollution sources. The key features include scalability, allowing for the addition of new sensors, and proactive decision-making through alerts when environmental parameters exceed predefined thresholds. This paper aims to empower communities with the knowledge needed to address and mitigate air pollution, creating healthier and more liveable urban environments in the face of rapid global urbanization. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative IoT-enabled crop storage monitoring system designed to revolutionize the preservation and quality assurance of stored agricultural produce. Central to this system are IoT sensors strategically deployed within storage facilities. These sensors are tasked with the continuous tracking and monitoring of crucial environmental parameters, specifically temperature, humidity, and gas levels. Leveraging this real-time data, the system is engineered to promptly detect and respond to any deviations from the prescribed optimal storage conditions. The core strength of this system lies in its ability to generate instantaneous alerts upon detecting irregularities. These alerts serve as preemptive measures, effectively averting potential spoilage and curtailing post-harvest losses by enabling timely interventions and corrective actions. By harnessing IoT technology, this paper aims to create a proactive, automated, and responsive framework that ensures the integrity and safety of stored agricultural produce, ultimately contributing to enhanced food security and sustainability. [ABSTRACT FROM AUTHOR]

Preventive Conservation (PC) aims to minimize the risk of irreversible damage to cultural artifacts caused by environmental factors. Strategies for PC include implementing environmental recommendations and monitoring conditions. However, environmental monitoring alone is not enough, and predictive analysis is needed to assess the risk of damage. The collection "Preventive Conservation, Predictive Analysis and Environmental Monitoring" presents technological advances in studying material degradation and environmental monitoring. Papers cover topics such as paper degradation, wood degradation, canvas paintings, dyed textiles, sensor electronics, wireless communications, cloud computing, and machine learning. The collection provides valuable insights for the design of preventive conservation strategies. [Extracted from the article]

A fluorescence sensing system based on supramolecular assembly of a perylene probe (PDI-BTMA) has been constructed to rapidly and accurately quantify TNP via smartphone. [Display omitted] • Smartphone-assisted fluorescence sensor based PDI-BTMA probe was constructed for TNP. • Visual sensing of TNP was accomplished rapidly in aqueous media with LOD of 9 nM. • Optical responses of PDI-BTMA were caused by the formation of supramolecular complex. • The sensor can detect TNP quantitatively with sensitivity in environmental samples. 2,4,6-trinitrophenol (TNP) is an environmentally deleterious substance with high toxicity and explosibility. It is of great significance for environmental protection and public health to establish a rapidly on-site monitoring method for perilous TNP. Current methods for detecting TNP mainly rely on traditional laboratory analysis lacking rapid detection through intelligent modes. Herein, we construct a smartphone recognition based fluorescence sensing system via the supramolecular assembly of a perylene probe to quantify TNP. The sensing platform consists of a fluorescent probe based on quaternary ammonium functionalized perylene (PDI-BTMA), as the TNP-response recognition element, and smartphones as optical signals receptors bringing simpleness, celerity, and portability for TNP monitoring. The sensor reveals dual output signals of color and fluorescence in response to TNP. The results show that the optical responses of PDI-BTMA can be attributed to the formation of the supramolecular complex (PDI-BTMA/TNP) via non-covalent interactions including static electricity, hydrophobic interaction, charge transfer, and π-π stacking. It shows a wide linear range for TNP of 200–1200 nM with a detection limit of 9 nM. In addition, we successfully made portable PDI-BTMA fluorescence paper. The RGB value of fluorescence color was also collected by using the smartphone-assisted sensing platform, and the G/B channel values show a linear relationship with TNP concentration in 0.1–50 μM, with the lowest detection concentration of 48.4 nM. Additionally, it could be successfully utilized for quantitative TNP monitoring in environmental water and soil samples, which achieved a greater recovery rate in the range of 99–110%. This research integrating the PDI-BTMA probe with a smartphone firstly presents a new strategy for real-time and on-site monitoring of TNP in the environment. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (microPADs) are an emerging platform for point-of-care assays with potential applications ranging from medical diagnostics to environmental monitoring. A standard approach for signal generation and amplification on microPADs is the use of enzymes and chromogenic substrates, which produce colored products and enable the qualitative and quantitative detection of analytes. Horseradish peroxidase (HRP) is one of the most commonly used enzymes for this application. While a wide variety of chromogenic substrates and substrate solutions are available for HRP, these were all originally developed and optimized for other platforms and have not been systematically compared on microPADs. In this work, 33 chromogenic substrate solutions for HRP containing one of six different substrate molecules were evaluated in a standardized colorimetric assay and compared on the basis of limit of detection (LOD), lower limit of quantitation (LLOQ), upper limit of quantitation (ULOQ), sensitivity, dynamic range, stability, and cost. While the substrates tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) were found to achieve the best overall analytical performance, each substrate had characteristics that may make them appealing for specific applications. The results of this work will facilitate the selection of substrate molecules and the formulation of substrate solutions for future colorimetric paper-based assays involving HRP. • Six chromogenic substrates for HRP in 33 different formulations were evaluated on microPADs. • TMB and OPD provided the best overall LOD, LLOQ and sensitivity. • ABTS provided the best ULOQ and dynamic range. • Results will facilitate the selection of suitable substrates for future applications. [ABSTRACT FROM AUTHOR]

Primary aromatic amines (PAAs) are a class of hazardous substances where many compounds are classified as carcinogen, mutagen, and reproduction toxin (CMR). PAAs can be taken up by dermal exposure. In the polyurethane industry, a valid and trustworthy method for the quantification of PAAs in the presence of isocyanates that could interfere is of great interest, especially on workplaces where a regular contact to PAAs cannot be excluded. The aim of this work is the development, validation, and verification of a novel sampling device to quantify selectively the PAA load on work surfaces. We describe the synthesis of Cell-ßALA-PEMSA analytical papers and their characterization by infrared spectroscopy and thermogravimetric analysis. The recovery of TDA and MDA spiked on these filters is satisfactory. An excellent selectivity of Cell-ßALA-PEMSA papers towards PAAs in the presence of isocyanates of almost 100% was found by wipe tests of amine/isocyanate contaminated surfaces. First positive field tests were achieved at certain areas in a Polyurethane Technical Application Department where surface contamination with PAAs was expected, and the Cell-ßALA-PEMSA analytical papers were superior to an established method of surface sampling. However, recovery of these amines from surfaces shows a large variability, and more work is required to address influencing surface properties. [ABSTRACT FROM AUTHOR]

In today's world, a significant amount of global energy is used in buildings. Unfortunately, a lot of this energy is wasted, because electrical appliances are not used properly or efficiently. One way to reduce this waste is by detecting, learning, and predicting when people are present in buildings. To do this, buildings need to become "smart" and "cognitive" and use modern technologies to sense when and how people are occupying the buildings. By leveraging this information, buildings can make smart decisions based on recently developed methods. In this paper, we provide a comprehensive overview of recent advancements in Internet of Things (IoT) technologies that have been designed and used for the monitoring of indoor environmental conditions within buildings. Using these technologies is crucial to gathering data about the indoor environment and determining the number and presence of occupants. Furthermore, this paper critically examines both the strengths and limitations of each technology in predicting occupant behavior. In addition, it explores different methods for processing these data and making future occupancy predictions. Moreover, we highlight some challenges, such as determining the optimal number and location of sensors and radars, and provide a detailed explanation and insights into these challenges. Furthermore, the paper explores possible future directions, including the security of occupants' data and the promotion of energy-efficient practices such as localizing occupants and monitoring their activities within a building. With respect to other survey works on similar topics, our work aims to both cover recent sensory approaches and review methods used in the literature for estimating occupancy. [ABSTRACT FROM AUTHOR]

Paper-based analytical devices (PADs), including lateral flow assays (LFAs), dipstick assays and microfluidic PADs (μPADs), have a great impact on the healthcare realm and environmental monitoring. This is especially evident in developing countries because PADs-based point-of-care testing (POCT) enables to rapidly determine various (bio)chemical analytes in a miniaturized, cost-effective and user-friendly manner. Low sensitivity and poor specificity are the main bottlenecks associated with PADs, which limit the entry of PADs into the real-life applications. The application of nanomaterials in PADs is showing great improvement in their detection performance in terms of sensitivity, selectivity and accuracy since the nanomaterials have unique physicochemical properties. In this review, the research progress on the nanomaterial-based PADs is summarized by highlighting representative recent publications. We mainly focus on the detection principles, the sensing mechanisms of how they work and applications in disease diagnosis, environmental monitoring and food safety management. In addition, the limitations and challenges associated with the development of nanomaterial-based PADs are discussed, and further directions in this research field are proposed. [ABSTRACT FROM AUTHOR]

• This manuscript reviews the history and new developments of ePADs from 2016 to 2021. • This review focuses on construction and representative applications of ePADs. • The limiting factors and future development of ePADs have been discussed. Integration of electrochemical detection methods into paper-based analytical devices (PADs) provides a powerful tool for the area of point-of-care testing (POCT) because the electrochemical PADs (termed as ePADs) enable to rapidly determine a broad spectrum of analytes from ions to living cells in a miniaturized, cost-effective and user-friendly manner. Recently, nanomaterials and their composites were extensively introduced in ePADs for improvement of their detection performance. This review attempts to provide a comprehensive information on the ePADs including a general aspect of ePADs and recent development of ePADs by highlighting selected publication. We mainly focus on the fabrication of ePADs, enhancement strategies of nanomaterials and potential applications of ePADs in the fields of environmental monitoring, food safety management and disease diagnosis. Based on the limitations and challenges associated with the development of ePADs, the future perspectives of this research field are proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A portable nanocluster-modified paper analytical device integrated with a syringe for highly sensitive Hg2+ detection. • The CMC-EDC/NHS method attaches AuNCs to the substrate, preventing the AuNCs from leaching. • This platform accumulates the signal of Hg2+ by flowing with increased solution volume. • The platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM. To minimize the need for complex testing procedures, sophisticated instrumentation, and electricity for on-site testing, we demonstrate a simple and portable gold nanocluster (AuNC)-modified paper analytical device integrated with syringe-driven fluid flow to enable highly sensitive mercury ion (Hg2+) detection for environmental monitoring. The device is composed of a paper substrate modified with fluorescent AuNCs (AuNC-paper), which is held within a reusable cartridge connected to a syringe, thus allowing users to flow a large volume of the sample solution through the paper test for greater accumulation of the analyte signal. The metallophilic d10-d10 interaction of Hg2+ with Au+ on the surface of the AuNC-paper induces fluorescence quenching, which can be monitored using a smartphone. Importantly, the red-emitting AuNCs avoid interference with the background fluorescence of the paper substrate. Additionally, the AuNCs are strongly-attached to the paper substrate via carbodiimide coupling, which helps prevent the AuNCs from leaching and enables a large amount of solution to interact with the test (up to 2.5 mL) to increase the amount of the target ions that react with the AuNC-paper. As a result, without the need for preconcentrating the test solution, this paper device can provide the highly sensitive detection of Hg2+ ions, including a 26-fold higher sensitivity than the AuNC-modified test paper without a fluidic cartridge, at a low level of down to nM. The paper platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM, which is less than the United States Environmental Protection Agency's regulatory limit for drinking water. This highly sensitive, selective, portable, and easy-to-operate platform may be valuable for on-site mercury pollution monitoring in resource-constrained settings. [ABSTRACT FROM AUTHOR]

Per- and polyfiuoroalkyl substances (PFAS) on paper packaging resist water and oil to effectively contain food and beverages. However, previous studies have established correlations between PFAS and several diseases including COVID-19, cancers, and obesity. The goal of this collaborative research between the Philippines and Singapore is to set a baseline for PFAS levels in local packaging with the intended outcome of further increasing awareness on these contaminants in Southeast Asia, providing a starting point for migration experiments and risk assessments on PFAS in commercially-available food contact materials and articles, and initiating policy developments on these substances in the Philippines. In this study, 15 different types of PFAS were analyzed in selected paper packaging used by major quick service restaurants (QSRs) in Metro Manila. Using liquid chromatography-mass spectrometry (LC-MS), PFAS was detected in 100% of the samples with a total PFAS concentration range of 8.20-97.7 ng PFAS/100 cm². The highest amount of PFAS compound measured across all samples was PF-3,7-DMOA (89.8 ng/100 cm²). PFAS compounds regulated in European packaging such as PFHpA, PFOA, PFNA and PFDA were also detected in all samples but at trace levels. Paper wrappers for rice and small burgers were found to have the highest total PFAS of 97.7 ng PFAS/100 cm². This value translates to approximately 65.1 ng F/100 cm² which is way below 10,000 ng F/100 cm², the currently existing limit for PFAS in packaging set by the Danish Ministry of Environment and Food. While each packaging may be deemed safe compared to regulation, the compounded effects brought by use of multiple packaging, and high frequency and long-term exposures require further investigation. [ABSTRACT FROM AUTHOR]

The development of low-cost analytical devices for on-site water quality monitoring is a critical need, especially for developing countries and remote communities in developed countries with limited resources. Microbial electrochemical cell-based (MXC) biosensors have been quite promising for quantitative and semi-quantitative (often qualitative) measurements of various water quality parameters due to their low cost and simplicity compared to traditional analytical methods. However, conventional MXC biosensors often encounter challenges, such as the slow establishment of biofilms, low sensitivity, and poor recoverability, making them unable to be applied for practical cases. In response, MXC biosensors assembled with paper-based materials demonstrated tremendous potentials to enhance sensitivity and field applicability. Furthermore, the paper-based platforms offer many prominent features, including autonomous liquid transport, rapid bacterial adhesion, lowered resistance, low fabrication cost (<$1 in USD), and eco-friendliness. Therefore, this review aims to summarize the current trend and applications of paper-based MXC biosensors, along with critical discussions on their field applicability. Moreover, future advancements of paper-based MXC biosensors, such as developing a novel paper-based biobatteries, increasing the system performance using an unique biocatalyst, such as yeast, and integrating the biosensor system with other advanced tools, such as machine learning and 3D printing, are highlighted. [Display omitted] • Studies related to paper-based MXC biosensors are summarized and reviewed. • Benefits of using paper-based platforms over traditional materials are listed. • Current applications and challenges of paper-based MXC biosensors are provided. • Field applicability of paper-based MXC biosensors is highlighted. • Opportunities to integrate 3D printing and machine learning are discussed. [ABSTRACT FROM AUTHOR]

Lab-on-paper technologies, also known as paper-based analytical devices (PADs), have received increasing attention in the last years, and nowadays, their use has spread to virtually every application area, i.e., medical diagnostic, food safety, environmental monitoring, etc. Advantages inherent to on-field detection, which include avoiding sampling, sample preparation and conventional instrumentation in central labs, are undoubtedly driving many developments in this area. Heavy metals represent an important group of environmental pollutants that require strict controls due to the threat they pose to ecosystems and human health. In this overview, the development of PADs for Hg monitoring, which is considered the most toxic metal in the environment, is addressed. The main emphasis is placed on recognition elements (i.e., organic chromophores/fluorophores, plasmonic nanoparticles, inorganic quantum dots, carbon quantum dots, metal nanoclusters, etc.) employed to provide suitable selectivity and sensitivity. The performance of both microfluidic paper-based analytical devices and paper-based sensors using signal readout by colorimetry and luminescence will be discussed. [ABSTRACT FROM AUTHOR]

This paper provides a thorough comparison of sophisticated biosensors and conventional sensors, explaining the underlying technologies, working theories, and performance measures of each in analytical detection applications. Through analyzing the essential distinctions and parallels between them, this paper brings to light the unique benefits and constraints of every technology with respect to sensitivity, specificity, reaction speed, and mobility. This paper also examines the various uses of sensors and biosensors in healthcare, environmental monitoring, and industrial processes, offering insights into the special qualities and possible collaborations of these platforms. Looking ahead, this paper explores new developments in data analytics, microfluidics, and nanotechnology that will lead to next-generation sensing technologies with improved analytical capabilities and wider practical uses. [ABSTRACT FROM AUTHOR]

The fast detection of trace amounts of hazardous contaminations can prevent serious damage to the environment. Paper-based sensors offer a new perspective on the world of analytical methods, overcoming previous limitations by fabricating a simple device with valuable benefits such as flexibility, biocompatibility, disposability, biodegradability, easy operation, large surface-to-volume ratio, and cost-effectiveness. Depending on the performance type, the device can be used to analyze the analyte in the liquid or vapor phase. For liquid samples, various structures (including a dipstick, as well as microfluidic and lateral flow) have been constructed. Paper-based 3D sensors are prepared by gluing and folding different layers of a piece of paper, being more user-friendly, due to the combination of several preparation methods, the integration of different sensor elements, and the connection between two methods of detection in a small set. Paper sensors can be used in chromatographic, electrochemical, and colorimetric processes, depending on the type of transducer. Additionally, in recent years, the applicability of these sensors has been investigated in various applications, such as food and water quality, environmental monitoring, disease diagnosis, and medical sciences. Here, we review the development (from 2010 to 2021) of paper methods in the field of the detection and determination of toxic substances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distinctive hydrophilic-hydrophobic SERS substrates have been fabricated utilizing ordinary papers loaded with Ag nanowires. • Remarkable SERS activity with an enhancement factor (EF) up to 2.63 × 106 was achieved. • An in-situ detection of trace furazolidone on fish under the interference of malachite green was realized. As a typical membrane matrix with attractive flexibility, paper has exhibited great feasibility to serve as surface-enhanced Raman scattering (SERS) substrate in the environmental monitoring and surveillance. In this research, we have designed and fabricated a distinctive hydrophilic-hydrophobic SERS substrate utilizing several ordinary papers loaded with Ag nanowires (Ag NWs). Remarkable SERS activities with an enhancement factor (EF) up to 2.63 × 106 was successfully achieved in the assembly Ag NWs with the optimal amount of nanotips and overlaps. The hydrophilic-hydrophobic strategy could contribute to anchoring microdroplets and thus enrich analytes to improve the homogeneity of substrate with a low relative standard deviation of 10.6%. Furthermore, the sophisticated SERS substrate was also applied in the in-situ detection of trace furazolidone on fish under the interference of malachite green and the reliable recovery rates were demonstrated as well. [ABSTRACT FROM AUTHOR]

This review paper provides an in-depth analysis of recent advancements in integrating two-dimensional (2D) materials with cellulose to enhance biosensing technology. The incorporation of 2D materials such as graphene and transition metal dichalcogenides, along with nanocellulose, improves the sensitivity, stability, and flexibility of biosensors. Practical applications of these advanced biosensors are explored in fields like medical diagnostics and environmental monitoring. This innovative approach is driving research opportunities and expanding the possibilities for diverse applications in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

Investigating effective fluorescence strategies for real-time monitoring of dipicolinic acid (DPA) is of paramount importance in safeguarding human health. Herein, we present the design of a desirable red-emissive carbon nanostructure anchoring a molecularly imprinted Er-BTC MOF as a fluorescence biosensor for the visual determination of DPA. DPA is a biomarker of Bacillus anthracis, a subcategory of serious infectious diseases and bioweapons. We introduce a paper test strip sensitized with the aforementioned nanostructure, which is integrated with online UV excitation and smartphone digital imaging, resulting in a DPA signal-off sensing platform. The proposed fluorometric visual paper-based biosensor demonstrates wide linear ranges for DPA (10–125 μM) with a LOQ and LOD of 4.32 and 1.28 μM, respectively. The designed platform exhibits impressive emission properties and adaptable surface functional groups, which confirm its desirable selective sensing capabilities against other biological molecules and DPA isomers. As a proof of concept, DPA monitoring is successfully applied to real samples of tap water and urine. This integrated selective paper-based nano-biosensor, coupled with smartphone signal recording, holds great promise for state-of-the-art practical applications including fluorometric/colorimetric detection in healthcare and environmental monitoring, food safety analysis, and point-of-care testing. [ABSTRACT FROM AUTHOR]

Generalized target detection algorithms perform well for large- and medium-sized targets but struggle with small ones. However, with the growing importance of aerial images in urban transportation and environmental monitoring, detecting small targets in such imagery has been a promising research hotspot. The challenge in small object detection lies in the limited pixel proportion and the complexity of feature extraction. Moreover, current mainstream detection algorithms tend to be overly complex, leading to structural redundancy for small objects. To cope with these challenges, this paper recommends the PCSG model based on yolov5, which optimizes both the detection head and backbone networks. (1) An enhanced detection header is introduced, featuring a new structure that enhances the feature pyramid network and the path aggregation network. This enhancement bolsters the model's shallow feature reuse capability and introduces a dedicated detection layer for smaller objects. Additionally, redundant structures in the network are pruned, and the lightweight and versatile upsampling operator CARAFE is used to optimize the upsampling algorithm. (2) The paper proposes the module named SPD-Conv to replace the strided convolution operation and pooling structures in yolov5, thereby enhancing the backbone's feature extraction capability. Furthermore, Ghost convolution is utilized to optimize the parameter count, ensuring that the backbone meets the real-time needs of aerial image detection. The experimental results from the RSOD dataset show that the PCSG model exhibits superior detection performance. The value of mAP increases from 97.1% to 97.8%, while the number of model parameters decreases by 22.3%, from 1,761,871 to 1,368,823. These findings unequivocally highlight the effectiveness of this approach. [ABSTRACT FROM AUTHOR]

This paper explores the impact of environmental protection tax on green technology innovation of Chinese resource-based enterprises and behavior of thirdparty environmental monitoring institutions. It uses game theory to analyze participants' strategy selections, and uses the triple difference method to empirically test the promotion effect. Our robust results find that (1) Chinese environmental tax policy effectively promotes the green innovation of resource-based enterprises and standardizes the behavior of third-party monitoring institutions; (2) local governments' actions such as increasing environmental protection tax, penalizing third-party monitoring agencies for violations, and promoting public preference for green consumption, all contribute to accelerating enterprises' green innovation; (3) the central government's increased regulation of local governments has a positive impact on enterprises and third-party monitoring institutions. [ABSTRACT FROM AUTHOR]

In this paper, we have developed the SEMAR (Smart Environmental Monitoring and Analytics in Real-Time) IoT application server platform for fast deployments of IoT application systems. It provides various integration capabilities for the collection, display, and analysis of sensor data on a single platform. Recently, Artificial Intelligence (AI) has become very popular and widely used in various applications including IoT. To support this growth, the integration of AI into SEMAR is essential to enhance its capabilities after identifying the current trends of applicable AI technologies in IoT applications. In this paper, we first provide a comprehensive review of IoT applications using AI techniques in the literature. They cover predictive analytics, image classification, object detection, text spotting, auditory perception, Natural Language Processing (NLP), and collaborative AI. Next, we identify the characteristics of each technique by considering the key parameters, such as software requirements, input/output (I/O) data types, processing methods, and computations. Third, we design the integration of AI techniques into SEMAR based on the findings. Finally, we discuss use cases of SEMAR for IoT applications with AI techniques. The implementation of the proposed design in SEMAR and its use to IoT applications will be in future works. [ABSTRACT FROM AUTHOR]

The rapid and accurate detection of ammonia is very important for manufacture and environmental monitoring, which needs to be developed urgently. Herein, a thin film‐based fluorescence sensor is fabricated by using a ternary europium (III) complex probe for ammonia. The new complex Eu(TPM)3(2‐PBO) (1) was designed and synthesized by utilizing a trifluoromethyl substituted β‐diketone ligand TPM and a diimine ligand 2‐PBO (TPM = 1,1,1‐trifluoro‐5,5‐dimethyl‐2,4‐hexanedione, 2‐PBO = 2‐(2′‐pyridyl)‐benzoxazole). This complex probe was synthetically characterized by elemental analysis, crystallographic and spectroscopic analysis, and photoluminescence (PL) study. The crystallographic analysis revealed complex 1 as a neutral complex structure with the Eu(III) center in a distorted square antiprism EuO6N2 coordination polyhedron. Based on this complex probe, a thin film fluorescence sensor with highly sensitive and selective response to ammonia was developed by polymethyl methacrylate (PMMA): complex composite and cellulose paper support. When the paper‐based sensor was exposed to ammonia, its PL emission showed a sensing behavior of rapid quenching. Surprisingly, this new method can achieve excellent limit of detection as low as 2.740 × 10−6 ppm. [ABSTRACT FROM AUTHOR]

Effective environmental monitoring has become a worldwide concern, requiring the development of novel tools to deal with pollution risks and manage natural resources. However, a majority of current assessment methods are still costly and labor-intensive. Thanks to the rapid advancements in microfluidic technology over the past few decades, great efforts have been made to develop miniaturized tools for rapid and efficient environmental monitoring. Compared to traditional large-scale devices, microfluidic approaches provide several advantages such as low sample and energy consumption, shortened analysis time and adaptabilities to onsite applications. More importantly, it provides a low-cost solution for onsite environmental assessment leveraging the ubiquitous materials such as paper and plastics, and cost-effective fabrication methods such as inkjet printing and drawing. At present, devices that are disposable, reproducible, and capable of mass production have been developed and manufactured for a wide spectrum of applications related to environmental monitoring. This review summarizes the recent advances of low-cost microfluidics in the field of environmental monitoring. Initially, common low-cost materials and fabrication technologies are introduced, providing a perspective on the currently available low-cost microfluidic manufacturing techniques. The latest applications towards effective environmental monitoring and assessment in water quality, air quality, soil nutrients, microorganisms, and other applications are then reviewed. Finally, current challenges on materials and fabrication technologies and research opportunities are discussed to inspire future innovations. [ABSTRACT FROM AUTHOR]

The successful application of cutting-edge computer vision technology to automatic insect classification has long been a focus of research in insect taxonomy. The results of this research have a wide range of applications in areas such as environmental monitoring, pest diagnosis and epidemiology. However, there is still a gap between the current techniques used in automatic insect classification and the latest computer vision techniques. The research in this paper is conducted on Lepidoptera, a class of insects that are widely infested, including butterflies and moths. The study focuses on the application of deep learning algorithms in image processing of Lepidoptera insects. In order to improve the recognition rate for Lepidoptera insect recognition, this paper uses a detection model based on deep neural networks to realize the recognition of Lepidoptera insects in complex environments. Specifically, the yolov7 algorithm is adopted as the basic model for this experiment, and the reasons for using this model are explained in terms of the splicing of network modules, loss function, positive sample allocation strategy, and the merging of convolution and normalization, respectively. Through experiments, it is proved that the algorithm can effectively improve the gesture recognition rate, the recognition accuracy reaches 79.5%, and the recognition speed is as high as 33.08it/s. [ABSTRACT FROM AUTHOR]