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A new class of eutectogel with hydrophilic/hydrophobic heterogeneous network is reported. The flexible and conductive eutectogel shows conspicuous transparency, solvent resistance, solvent retention and antibacterial performance. The assembled eutectogel sensor can be applied to detect human motion and underwater communication with satisfactory sensitivity, accuracy, and repeatability. [Display omitted] In recent years, gel-based ion conductor has been widely considered in wearable electronics because of the favorable flexibility and conductivity. However, it is of vital importance, yet rather challenging to adapt the gel for underwater and dry conditions. Herein, an anti-swelling and anti-drying, intrinsic conductor eutectogel is designed via a one-step radical polymerization of acrylic acid and 2, 2, 2‑trifluoroethyl methacrylate in binary deep eutectic solvents (DESs) medium. On the one hand, the synergistic effects of hydrophilic/hydrophobic heteronetworks can elicit the integrity stability of eutectogel in liquid environment. It is proved that both the mechanical property and conductivity are maintained after immersing in different salt, alkaline and acid solution and organic solvent for one month. On the other hand, the eutectogel inherits well conductivity (93 mS/m), anti-drying and antibacterial properties from DESs. Based on the above features, the resulting eutectogel can be assembled as smart sensor for stable information transmission in air and underwater with fast response time (1 s), high sensitivity (Gauge factor = 1.991) and long-time reproducibility (500 cycles, 70 % strain). Considering the simple preparation and integration of multiple functions, the binary cooperative complementary principle can provide insights into the development of next-generation conductive soft materials. [ABSTRACT FROM AUTHOR]

• PMMA particles are developed by emulsifier-free emulsion polymerization. • PMMA–HEMA particles could form crystalline structural color in HEMA solvent. • PMMA–HEMA–PDA particles with different amounts of melanin (PDA) doped are prepared. • PMMA–HEMA–PDA particle with 1.926 mM DA·HCl could improve the coloring of pHEMA film. Because of their flexible structure and adjustable color, structural colors with non-close-packed colloidal crystal arrays (NCCAs) have broad applications. However, most of these structural colors are limited by an approximate refractive index or high background scattering, and they present an unsatisfactory color that seriously hinders their practical application. Preparation of particles with a high refractive index or adsorption coefficient may be an effective approach to construct highly colorimetric NCCA structural colors in a nonaqueous solvent. The aim of this study was to explore the formation process of NCCA by the assembly of colloidal particles in a nonaqueous solvent, so as to fabricate NCCAs with a high refractive index and high adsorption. An attempt was made to fabricate the NCCA structural color by dispersing the desired particles in a 2-hydroxyethyl methacrylate (HEMA) solvent. Surface-functionalized poly(methyl methacrylate) (PMMA) particles were developed by emulsifier-free emulsion polymerization. The formation of NCCA was studied by comparing the dispersion of three classes of surface-functionalization of colloidal particles in the HEMA solvent. The melanin-like particles with a high refractive index and a high adsorption coefficient were synthesized by doping polydopamine (PDA) into good surface-functionalization particles by emulsifier-free emulsion polymerization. A highly colorimetric poly(2-hydroxyethyl methacrylate) (pHEMA) optical film with NCCA was fabricated by dispersing the melanin-like particles in a pHEMA hydrogel. PMMA-HEMA colloidal particles could successfully construct a NCCA structure in a nonaqueous HEMA solvent because of the solvation. Based on the "good particles," PMMA-HEMA-PDA colloidal particles, an initial 3-hydroxytyramine hydrochloride (DA·HCl) concentration of 1.926 mM was shown to significantly improve the colorimetric value of the final solidified NCCA hydrogel. These results provided an important reference for the construction of surfactant-free HEMA non-close-packed colloidal crystals. This highly colorimetric structurally colored hydrogel may be widely used in the design of a variety of colored intelligent sensors and soft devices. [ABSTRACT FROM AUTHOR]

Heavy metal ion (HMI) sensors are the most sought commercial devices for environmental monitoring and food analysis research due to serious health concerns associated with HMI overdosage. Herein, we developed an effective electrochemical sensor for simultaneous detection of four HMI (Cd2+, Pb2+, Fe2+, and Cu2+) using a ternary nanocomposite of reduced graphene oxide functionalized with polydopamine and alanine (ALA/pDA/rGO). Comprehensive spectroscopic and microscopic characterizations were performed to ensure the formation of the ternary nanocomposite. The developed nanocomposite on glassy carbon electrode (GCE) yields >2-fold higher current than GO/GCE electrode with excellent electrochemical stability and charge transfer rate. Using DPV, various chemical and electrochemical parameters, such as supporting electrolyte, buffer pH, metal deposition time, and potential, were optimized to achieve highly sensitive detection of targeted HMI. For Cd2+, Pb2+, Fe2+, and Cu2+ sensing devised sensor exhibited detection limits of 1.46, 2.86, 50.23, and 17.95 ppb and sensitivity of 0.0929, 0.0744, 0.0051, and 0.0394 μA/ppb, respectively, with <6% interference. The sensor worked similarly well for real water samples with HMI. This study demonstrates a novel strategy for concurrently detecting and quantifying multiple HMI in water and soil using a smart ternary nanocomposite-based electrochemical sensor, which can also detect HMI in food samples. • Development of highly effective electrochemical sensor for simultaneous detection Cd2+, Pb2+, Fe2+, and Cu2+ ions. • Ternary nanocomposite consisting of alanine, polydopamine, and reduced graphene oxide was used as the sensing material. • The sensor showed a low detection limit, excellent stability, and great reproducibility for metal ion detection. • The sensor detects Cd2+, Pb2+, Fe2+, and Cu2+ ions in real samples. [ABSTRACT FROM AUTHOR]

Indoor air quality (IAQ) is an important parameter in protecting the occupants of an indoor environment. Previous studies have shown that an indoor environment with poor ventilation increases airborne virus transmission. Existing research has concluded that high ventilation rates can reduce the risk of individuals in indoor environments being infected. However, most existing ventilation systems are designed to be efficient under non-pandemic conditions. Ultimately, indoor environments will become hotspots for the transmission of airborne viruses. Current infection risk assessments can estimate virus transmission via airborne routes, but with limited information sharing among stakeholders. Our own research did not identify any systems that integrate risk assessments with smart sensors in order to support information sharing with experts in indoor environments in their decision-making process. To fill this gap, we designed a blockchain-based prototype (AIRa) that integrates CO 2 smart sensor data with infection risk assessments from a post-pandemic perspective. This system generates two types of alerts: (1) P-Alert and (2) R0-Alert for decision-making by building owners, such as increasing the ventilation rate or track and trace, as needed. AIRa shows various benefits over three existing infection-control alert systems. Our solution stores and shares information such as the timestamp and room number, instead of storing building user's personal information. Our approach does not require a QR code to be scanned or a mobile app to be downloaded in order to enable track and trace. However, AIRa is still an early prototype for evaluating the risks of airborne virus transmission in smart building environments. Multidisciplinary knowledge and technological research will be vital in formulating different alerts in the future. • Complex supply chain makes information-sharing challenging. • Lack of processing of sensor data to useful information for decision making. • A blockchain-based framework that integrates risk assessments and sensors. • Passive and touchless approach to trace occupant within indoor environment. [ABSTRACT FROM AUTHOR]

The study of metal-organic frameworks (MOFs) as luminescence sensors for the detection of polluting molecules and ions are of great importance to the health of all creatures in the world. In this research field, lanthanide ions, especially for Eu3+ and Tb3+, have intrinsic advantages based on their outstanding luminescent properties. To develop smart luminescence sensors towards heavy metal ions and acid anions, two new lanthanide(III)-based MOFs: {[Ln 2 (btpdc) 3 ·DMF·2H 2 O]·2DMF·4H 2 O} n (Ln ​= ​Eu (1), Tb (2), H 2 btpdc ​= ​benzo[ b ]thiophene-2,6-dicarboxylic acid) were designed and synthesized under solvothermal condition based on a dicarboxylate ligand H 2 btpdc. Single crystal X-ray diffraction tests show the two complexes are isostructural with three dimensional (3D) porous framework structure. Notably, both of them exhibit good chemical stability in water. Under the excitation of ultra-violet light, 1 can exhibit strong Eu3+-based red light emission in both solid state and aqueous suspension while 2 doesn't show observable luminescence emission. The luminescence sensing experiments performed on 1 reveal that it can be employed as a smart "turn-off" luminescence sensor for the detection of Fe3+ or S2− in aqueous solution with high selectivity, low detection limit, good anti-interference ability and recyclability. The obtained quenching constant K sv and detection limits are 2.316 ​× ​104 ​M−1 and 0.26 ​μM, respectively, for Fe3+, and 1.38 ​× ​104 ​M−1 and 1.05 ​μM, respectively, for S2−. Based on a sulfur-contained ligand, a Eu3+ MOF was synthesized which exhibits high performance in luminescence sensing of Fe3+ and S2− in aqueous solution with host-guest interaction. [Display omitted] • Two new lanthanide metal-organic frameworks are synthesized and fully characterized. • The two MOFs have a short synthesis period of 4 ​h. • The two MOFs show high thermal stabilities and are stable to water. • Eu-MOF is a smart luminescent sensor for Fe3+ or S2− detection. [ABSTRACT FROM AUTHOR]

Air quality (AQ) is a global concern for human health management. Therefore, air quality monitoring (AQM) and its management is a must-needed activity for the current world environment. A systematic review of various sensors and systems for AQ management may strengthen our understanding of the monitoring and management of AQ. Thus, the current review presents details on sensors/systems available for AQ assessment, monitoring, and management. First, we had gone through the published literature based on special keywords including AQM, Particulate Matter (PM), Carbon Mono-oxide (CO), Sulfur di-Oxide (SO2), and Nitrogen di-Oxide (NO2) among others, and identified the current scenario of research in AQ management. We discussed various sensors/systems available for the AQ management based on self-conceptualised five major categories including, ground-based AQS (wet chemistry) systems, ground-based digital sensors systems, aerial sensors systems, satellite-based sensors systems, and integrated systems. The prospects in the field of AQ assessment and management (AQA&M) were then discussed in detail. We concluded that the AQA&M can be better achieved by coupling new technologies like ground-based smart sensors, satellite remote sensing sensors, Geospatial technologies, and computational technologies like machine learning, Artificial intelligence, and Internet of Things (IoT). The current work may lead to a junction of information for connecting these sensors/systems, which is expected to be beneficial in future AQ research and management. [Display omitted] • Geo-enabled smart sensor networks may support developing nations for achieving clean air goals of SDGs. • A Satellite-based systems are adaptive in AQM. • The amalgamation of laboratory, field, and geospatial technology-based sensors/systems are the effective future solution for AQ management. • Human health management at a regional and global scale can be achieved through integrated systems. [ABSTRACT FROM AUTHOR]