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In this study, we used the non-hydrolytic sol–gel methodology to synthesize gadolinium vanadate particles doped with different Er3+ and Yb3+ molar ratios. Er3+ and Yb3+ chlorides and vanadium alkoxide were used as precursors during the sol–gel synthesis. The resulting powders were treated at 800 °C and characterized by x-ray diffraction and photoluminescence. The x-ray diffractogram displayed peaks attributed to the gadolinium vanadate matrix. Photoluminescence helped to evaluate the Fluorescence Intensity Ratio (FIR), which is important for understanding the nanothermometer property. The FIR of the GdVO4:Er3+/Yb3+ samples containing different Er3+ and Yb3+ molar ratios increased as a function of the laser power, which indicated that the local temperature increased. The excitation spectra obtained at fixed wavelengths of 525 and 555 nm displayed bands at 322, 379, and 489 nm, ascribed to the charge transfer band and Er3+ levels. Upon excitation at 321 nm, the emission spectra in the visible region presented intense bands at 525 and 555 nm, due to Er3+ emission, and excitation at 321 nm led to emission in the infrared region, 980 and 1550 nm. In conclusion, the synthesized system can be employed as a temperature sensor. [ABSTRACT FROM AUTHOR]

This work suggests an all-digital temperature sensor with a high sampling rate that is based on a time-to-digital converter (TDC). Two on-chip voltage-controlled oscillators (VCOs) are used in the design of the sensor core, which senses temperatures between − 4 0 ∘ C and 200 ∘ C. For digital code conversion, the outputs of the VCO are fed into two asynchronous counters. In both low- and high- resolution modes, the error following two-point calibration is observed between − 1. 0 8 ∘ C and + 1. 0 6 ∘ C. The sensor's ability to function in both high- and low-resolution modes based on conversion time is an important feature. At a sampling frequency of 0.19 MHz, the maximum resolution achieved is 0.18 ∘ C. Additionally, the sensor has control logic built in to turn off the sensing as soon as the conversion is complete. At 90-nm process, 1.1 V supply voltage and 27 ∘ C, the proposed sensor occupies 0. 0 4 4 mm 2 and consumes 8 1 7. 5 μ W. [ABSTRACT FROM AUTHOR]

The traditional real-time load warning method for distribution transformers has problems such as low recall rate, low warning accuracy, and long warning time, which may lead to potential equipment failures or overload situations not being detected and dealt with in a timely manner, increasing the safety risk of transformer operation and potentially causing safety issues such as equipment damage, fire, or power outage. Therefore, a real-time early warning method of distribution transformer load considering meteorological factor data is designed. The meteorological factor data are collected by the light sensor, humidity sensor, temperature sensor and rainfall sensor, and the load data collection architecture is built by the load monitor, central master station and maintenance station to realize the load data collection of the distribution transformer. The K-nearest neighbor (KNN) method is used to process the missing values of the data, and the LOF algorithm is used to determine the local outliers and eliminate the outliers in the data set to achieve data cleaning. Considering the load loss, hot spot temperature and meteorological factors of the distribution transformer, an early warning model is built, and the cleaned data are input into the model to realize Real-time early warning of the distribution transformer load. The experimental results show that the recall rate of this method varies from 95% to 97%, the accuracy rate of early warning is always above 94%, and the maximum value of early warning time is 0.63s. Having good early warning ability. [ABSTRACT FROM AUTHOR]

The accurate detection of hazardous gases and monitoring of ambient temperature are crucial for preserving the ecological environment, safeguarding human health, and fostering industrial advancement. In this research, a straightforward hydrothermal technique was employed to synthesize the heterogeneous nanocomposite structure of CsPbBr 3 /SnWO 4 , which facilitates the detection of ethanolamine gas at room temperature. The synthesized CsPbBr 3 /SnWO 4 heterostructures underwent further analysis using XRD, SEM, HRTEM, XPS, BET and Mott-Schottky techniques. The findings revealed that the CsPbBr 3 /SnWO 4 heterostructure exhibits a coarse cubic morphology, consisting of nano-cubic CsPbBr 3 and nano-sheet SnWO 4. Additionally, the integration of CsPbBr 3 markedly enhances the specific surface area of the pristine SnWO 4 nanosheets. Due to its coarse surface, expansive contact area, and n-n heterojunction, CsPbBr 3 –SnWO 4 demonstrates remarkable selectivity, superior long-term stability, and a sensitivity of 45.6 to ethanolamine at ambient temperature. In conclusion, the CsPbBr 3 /SnWO 4 heterostructure, constructed from a cube with a rough surface, is anticipated to serve as an effective room temperature sensor with heightened selectivity for ethanolamine. [ABSTRACT FROM AUTHOR]

Low-temperature methane (CH 4) gas sensors with high performance have garnered substantial interest due to their potential to reliably monitor CH 4 and achieve intrinsic safety. In this work, we explored strategies that combine photo-activation with bimetallic decoration. ZnO, Au/ZnO, Ag/ZnO and bimetallic AuAg/ZnO microspheres were synthesized to evaluate their CH 4 sensing capabilities and were characterized using various techniques. The synthesized samples exhibited hollow structures and favourable optical properties. Their sensing performance was assessed at room temperature under 365 nm ultraviolet (UV) illumination. Among these, the AuAg/ZnO microspheres demonstrated superior CH 4 sensing performance, characterized by low detection temperature (room temperature), a high-response value (62.61–5000 ppm CH 4) and a rapid response time (5 s). Furthermore, the response of AuAg/ZnO exceeded that of Au/ZnO (42.29), Ag/ZnO (36.37) and pure ZnO (12.52), being five times higher than that of pure ZnO. The enhanced gas-sensing performance can likely be attributed to the UV light and the synergistic effects of the bimetallic AuAg. This study provides insights into the development of high-performance, room-temperature CH 4 sensors. [ABSTRACT FROM AUTHOR]

This study presents a novel refractive index sensor based on Fano resonance, incorporating a metal-insulator-metal (MIM) waveguide coupled with a circular ring structure (CRC). Using finite element method analysis, we investigated the propagation properties of the sensor. To evaluate their influence on sensor performance, we systematically varied the parameters of each Circular Resonant Cavity structure component, including the refractive index, employing a controlled variable approach. At its optimal configuration, the sensor achieves a maximum sensitivity of 3,240 nm/RIU and a figure of merit (FOM) of 57.9. With its high sensitivity, straightforward design, and suitability for temperature detection, the refractive index sensor holds promise for diverse applications. [ABSTRACT FROM AUTHOR]

A Mach-Zehnder interferometer (MZI) sensor based on thin-core fiber (TCF) is proposed. Sensitive materials such as polydimethylsiloxane (PDMS) or gelatin are coated on the surfaces of MZIs to achieve temperature, pressure, and humidity measurements. MZI is composed of single mode fiber (SMF), TCF, and multimode fiber (MMF) spliced together to form a "SMF-MMF-TCF-MMF-SMF" structure. The core/cladding diameters of TCF are 3.8 µm and 80 µm respectively. When three types of optical fibers with different core diameters are cascaded together, many cladding modes are excited to form MZI. Firstly, two similar MZI structures were fabricated designated by MZI1 and MZI2. In order to improve the sensitivity and mechanical strength, a layer of PDMS film was coated on the TCF surface of MZI1. Then, a layer of gelatin film is covered on the TCF surface of MZI2. PDMS has the high thermal expansion coefficient, thermal optical coefficient, and elasticity, and gelatin has good humidity sensitivity properties. The experimental results showed that the temperature and pressure sensitivity of MZI1 coated with PDMS reached −340 pm/°C and −14.3 nm/MPa, respectively, while the humidity sensitivity of MZI2 coated with gelatin reached −112.57 pm/% RH. When a fiber Bragg grating is cascaded with the MZI1, the sensor can achieve simultaneous measurement of temperature and pressure, eliminating crosstalk. The proposed sensor has an extremely simple structure and manufacturing method, which only involves the splicing of optical fiber and the coating by the film. In addition, the proposed sensor has a robust structure, good repeatability and stability, and high sensitivity, which has broad application prospects. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) like the zeolitic imidazolate framework (ZIF‐8) have a high surface area, tunable porosity, and robust thermal and chemical stability, making them attractive candidates for various applications. Here, a strategy is shown that spans that functionality and provides strong photoluminescence (PL) emission, unlocking ZIF‐8‐based materials for chemical and temperature sensors based on PL. The approach is based on laser processing that dramatically boosts the PL response of laser‐irradiated ZIF‐8 (LI ZIF‐8), achieving a 70‐fold increase in intensity relative to the pristine material. The PL characteristics of the irradiated material can be easily tuned by varying the laser power and irradiation time with in situ and real‐time spectroscopic analysis providing insights into the process dynamics. It is found that the observed PL enhancement is primarily due to the laser‐induced transformation of ZIF‐8 into nitrogen‐doped nanocarbons and ZnO nanostructures. The versatility of this laser processing approach is leveraged to create flexible electronics by integrating the LI ZIF‐8/nanocarbon architectures into thermoplastic polyurethane (TPU). The multifunctional composite material shows excellent performance as flexible electrodes for human‐body monitoring applications, as well as both temperature and flexure sensors with remarkable mechanical resilience. [ABSTRACT FROM AUTHOR]

This paper seeks to progress the field of topological photonic crystals (TPC) as a promising tool in face of construction flaws. In particular, the structure can be used as a novel temperature sensor. In this regard, the considered TPC structure comprising two different PC designs named PC1 and PC2. PC1 is designed from a stack of multilayers containing Silicon (Si) and Silicon dioxide (SiO2), while layers of SiO2 and composite layer named hyperbolic metamaterial (HMM) are considered in designing PC2. The HMM layer is engineered using subwavelength layers of Si and Bismuth Germinate, or BGO ( Bi 4 Ge 3 O 12 ). The mainstay of our suggested temperature sensor is mainly based on the emergence of some resonant modes inside the transmittance spectrum that provide the stability in the presence of the geometrical changes. Meanwhile, our theoretical framework has been introduced in the vicinity of transfer matrix method (TMM), effective medium theory (EMT) and the thermo-optic characteristics of the considered materials. The numerical findings have extensively introduced the role of some topological parameters such as layers' thicknesses, filling ratio through HMM layers and the periodicity of HMM on the stability or the topological features of the introduced sensor. Meanwhile, the numerical results reveal that the considered design provides some topological edge states (TESs) of a promising robustness and stability against certain disturbances or geometrical changes in the constituent materials. In addition, our sensing tool offers a relatively high sensitivity of 0.27 nm/°C. [ABSTRACT FROM AUTHOR]

In biomedical and optical applications, multifunctional upconverting nanoparticles (UCNPs) play an essential role where non‐invasive temperature sensing and imaging are necessary. UCNPs smaller than 20 nm, which can be excited under 808 nm wavelength, are particularly promising in this area and can be implemented in humans or other mammals. However, new versatile nanoprobes are still needed for biology, especially for challenging studies of small aquatic invertebrates. Such tools allow better monitoring and understanding of their physiology, biochemistry, and ecological responses, which is crucial due to the growing pollution of water reservoirs and climate change. Herein, multifunctional NaYF4:Yb3+, Er3+@NaNdF4:Yb3+ core@shell NPs (15 nm), forming stable aqueous colloids, exhibiting intense emissions under excitation in the first biological window (808 nm), and presenting high thermal sensitivity and resolution related to the thermally coupled energy levels of Er3+ ions, are designed and synthesized. Such properties of UCNPs are further utilized for optical imaging of aquatic invertebrates (Daphnia magna) and temperature detection inside their bodies under 808 nm excitation. This pioneering application of NaYF4:Yb3+, Er3+@NaNdF4:Yb3+ demonstrates the high potential of developed UCNPs for multifunctional applications, especially for bioimaging and temperature sensing within whole organisms. [ABSTRACT FROM AUTHOR]

Actuators containing sensors are developed for various applications. However, it is still challenging to equip miniaturized high‐precision sensors with actuators at the micrometer scale to achieve micro‐environment detection. Here, a two‐in‐one processing strategy to construct a sensor‐equipped magnetic actuator (SEMA) is proposed. The design of magnetic actuators is continuously optimized to achieve less resistance and faster acceleration. Besides, the temperature‐dependent properties of semiconductor quantum dots (QDs) are used to fabricate the temperature‐sensitive unit (TSU), with a sensitivity of up to 111 pm °C−1. Finally, as a proof of concept, the real‐time temperature detection of arbitrary micro‐area in microchannels is achieved. This method of equipping sensors with microactuators will bring many potential applications in microenvironment sensing, micro‐mechanical manipulating, and microcargo transporting. [ABSTRACT FROM AUTHOR]

AbstractTo optimize the drying process of bamboo bundles, this study investigates the heat and mass transfer behavior during the drying process by using temperature sensors to measure the temperature field at different positions and track the overall moisture content over time. Additionally, a heat transfer model is used to simulate and predict the drying process. The analysis of the experimental results indicates that the diameter of the bamboo bundles has a greater impact on the drying rate than the drying temperature. At the same temperature, the drying time significantly decreases as the temperature increases. Under drying conditions at 80 °C, the average drying rate constant is 0.072 for bamboo bundles with a diameter of 40 mm, whereas it is only 0.015 for bundles with a diameter of 100 mm. Using Newton’s law of cooling, the convective heat transfer coefficient calculation method was derived. The average convective heat transfer coefficients at 40, 60, and 80 °C were calculated to be 6.16 W/(m2 K), 7.14 W/(m2 K), and 7.22 W/(m2 K), respectively. A mathematical model was established for the temperature at the center of the bamboo bundles, the temperature of the drying medium, the diameter of the bamboo bundles, and the drying time. This model effectively simulates the temperature variation inside the bamboo bundles, and the temperature simulation data fits well with the measured values, with a standard error of less than 2.8 °C and a prediction error of less than 6.1%. This coupled model and method provide a theoretical basis for predicting and controlling the bamboo bundle drying process, reducing energy and time consumption in actual production. [ABSTRACT FROM AUTHOR]

In this paper, a temperature sensor based on a polymer–silica heterogeneous integrated Mach–Zehnder interferometer (MZI) structure is proposed. The MZI structure consists of a polymer waveguide arm and a doped silica waveguide arm. Due to the opposite thermal optical coefficients of polymers and silica, the hybrid integrated MZI structure enhances the temperature sensing characteristics. The direct coupling method and side coupling method are introduced to reduce the coupling loss of the device. The simulation results show that the side coupling structure has lower coupling loss and greater manufacturing tolerance compared to the direct coupling structure. The side coupling loss for PMMA material-based devices, NOA material-based devices, and SU-8 material-based devices is 0.104 dB, 0.294 dB, and 0.618 dB, respectively. The sensitivity (S) values of the three hybrid devices are −6.85 nm/K, −6.48 nm/K, and −2.30 nm/K, which are an order of magnitude higher than those of an all-polymer waveguide temperature sensor. We calculated the temperature responsivity (RT) (FSR→∞) of the three devices as 13.16 × 10−5 K, 32.20 × 10−5 K, and 20.20 × 10−5 K, suggesting that high thermo-optic coefficient polymer materials and the hybrid integration method have a promising application in the field of on-chip temperature sensing. [ABSTRACT FROM AUTHOR]

Fabricating strain sensors with high response in a wide temperature and strain range is still a challenge, especially in high temperature harsh environments. Herein, a dual‐functional sensor with cantilever beam structure is fabricated using polymer‐derived SiCN ceramics, which can be applied for temperature and stain monitor. The performance of the integrated sensor is evaluated from room temperature to 1000 °C and the related sensing mechanism is analyzed. The prepared strain sensor has ultrafast response of 60 ms in the strain range of 0–3500 µε and the maximum strain rate can reach 46 200 µε s−1. Moreover, the sensor has excellent stability and ultra‐high sensitivity under high temperature environments. Additionally, the temperature can be detected separately up to 1000 °C without any disturbance. This attractive integration sensor with competitive sensitivity, excellent stability, ultrafast response speed, and broad range, has great potential to detect temperature and strain signals for practical application in high temperature extreme environments. [ABSTRACT FROM AUTHOR]

This paper presents the preparation and characterization of transparent oxyfluoride glass ceramics (GCs) that contain nanocrystals of K 3 YF 6 co-doped with Dy3+ and Sm3+. The study investigates the luminescence characteristics, the process of energy transfer (ET) and the behavior of the ratio-metric temperature sensing. The formation of well-defined nanocrystals of K 3 YF 6 in the glass substrate was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By varying Sm3+ concentration, a tunable emission ranging from pale yellow to orange-red was observed. Energy transfer from Dy3+ to Sm3+ ions was confirmed through fluorescence spectra and decay curves. Sample K 3 YF 6 , containing 0.5 mol%Dy3+/1.2 mol%Sm3+, showed an absolute sensitivity (S a) of 0.635 % K−1 and relative sensitivity (S r) of 0.401 % K−1. These findings underscore the promising applications of K 3 YF 6 : Dy3+, Sm3+ GCs in multicolor displays and high-performance temperature sensing devices. [ABSTRACT FROM AUTHOR]

A pyroelectric temperature sensor for measuring human body temperature with increased accuracy and speed for application in mobile robotic systems has been developed. This pyroelectric temperature sensor for measuring human body temperature is intended for use in various educational institutions. Its usage will allow for identifying sick or potentially ill people and providing them with preliminary advice and avoid infecting other people. This is particularly important considering the seasonality of dangerous infectious diseases and the emergence of new ones (e.g., COVID-19). It is also advisable to use this pyroelectric sensor in hospitals, where temperature measurement is very crucial for monitoring the course of various diseases. The proposed pyroelectric temperature sensor is based on a nonlinear oscillatory system, which provides high sensitivity and allows for solving the problem of increasing the accuracy of measuring the human body temperature in a non-contact way. Measurement error is ±0.1% in the operating range (32–43) °C, measurement time—1 s, and the frequency instability is 3·10−4. [ABSTRACT FROM AUTHOR]

ABSTRACT Temperature in various scientific and industrial applications requires accurate detection and measurement. Herein, a range of novel isostructural lanthanide‐based metal–organic frameworks (Ln‐MOFs), [EuxTb2−x(3,5‐pdc)3(phen)2(H2O)2]n (x = 0, Tb‐MOF; x = 2, Eu‐MOF; x = 0.002, 0.010, 0.020, 0.040, 0.080, EuxTb2−x‐MOF), were solvothermally synthesized using 3,5‐pyridinedicarboxylic acid (3,5‐H2pdc) and 1,10‐phenanthroline (phen) as ligands. Based on binuclear second building units, Ln‐MOFs exhibited 2D layered structure with sql topology. The luminescent properties of series Ln‐MOFs show systematic tuning shifted from green to red by adjusting the ratio of Eu3+ to Tb3+. The temperature sensing experiments showed that Eu0.020Tb1.980‐MOF exhibited self‐calibration temperature response in a range of 293–413 K, achieving maximum relative sensitivity (Sr) 2.46%·K−1 at 413 K, outscoring many state‐of‐the‐art temperature sensors reported in literature. This study poses great promise of the newly designed Eu0.020Tb1.980‐MOF for the ultra‐sensitive temperature sensing in diverse and large‐scale applications. [ABSTRACT FROM AUTHOR]

Laser metal deposition (LMD) is a technology for the production of near-net-shape components. It is necessary to control the manufacturing process to obtain good geometrical accuracy and metallurgical properties. In the present study, a closed-loop control method of melt pool temperature for the deposition of small Ti6Al4V blocks in open environment was proposed. Based on the developed melt pool temperature sensor and deposition height sensor, a closed-loop control system and proportional-integral (PI) controller were developed and tested. The results show that with a PI temperature controller, the melt pool temperature tends to the desired value and remains stable. Compared to the deposition block without the controller, a flatter surface and no oxidation phenomenon are obtained with the controller. [ABSTRACT FROM AUTHOR]

The transition from wakefulness to sleep occurs when the core body temperature decreases. The latter is facilitated by an increase in the cutaneous blood flow, which dissipates internal heat into the micro-environment surrounding the sleeper's body. The rise in cutaneous blood flow near sleep onset causes the distal (hands and feet) and proximal (abdomen) temperatures to increase by about 1 °C and 0.5 °C, respectively. Characterizing the dynamics of skin temperature changes throughout sleep phases and understanding its relationship with sleep quality requires a means to unobtrusively and longitudinally estimate the skin temperature. Leveraging the data from a temperature sensor strip (TSS) with five individual temperature sensors embedded near the surface of a smart bed's mattress, we have developed an algorithm to estimate the distal skin temperature with a minute-long temporal resolution. The data from 18 participants who recorded TSS and ground-truth temperature data from sleep during 14 nights at home and 2 nights in a lab were used to develop an algorithm that uses a two-stage regression model (gradient boosted tree followed by a random forest) to estimate the distal skin temperature. A five-fold cross-validation procedure was applied to train and validate the model such that the data from a participant could only be either in the training or validation set but not in both. The algorithm verification was performed with the in-lab data. The algorithm presented in this research can estimate the distal skin temperature at a minute-level resolution, with accuracy characterized by the mean limits of agreement [−0.79 to +0.79 °C] and mean coefficient of determination R 2 = 0.87 . This method may enable the unobtrusive, longitudinal and ecologically valid collection of distal skin temperature values during sleep. Therelatively small sample size motivates the need for further validation efforts. [ABSTRACT FROM AUTHOR]

To accurately, efficiently and stably predict the thermal displacement of the spindle, a prediction model based on the beluga whale algorithm (BWO) optimized bi-directional long and short-term memory neural network (BiLSTM) is introduced in this paper. Firstly, the thermal characterization and simulation analysis of the spindle are carried out, and the temperature and thermal displacement change characteristics of the spindle are obtained. Then the thermal deformation experiment of the spindle is carried out, and the temperature and displacement sensors are set up reasonably according to the temperature and thermal displacement change characteristics of the spindle, and the experimental data are collected and analyzed. The adaptive and globally convergent BWO is selected to optimize network parameters of BiLSTM, and the BWO-BiLSTM prediction model is constructed by learning the nonlinear correlation characteristics between spindle temperature and axial thermal displacement. The constructed BWO-BiLSTM prediction model is compared with other prediction models, and it is found through analysis that the prediction results output from the BWO-BiLSTM model have better accuracy and stability. The results of the study can provide a certain theoretical basis and technical support in predicting the spindle thermal displacement, which can help to promote the precision machining production of electric spindles. • Spindle thermal characterization and simulation studies are carried out. • Significant changes in axial temperature and thermal displacement are found. • Sensors are set up according to the results of studies. • A BWO-BiLSTM model is built to predict the spindle thermal displacement. [ABSTRACT FROM AUTHOR]

The precise thermal error prediction of spindle-bearing systems (SBSs) necessitates a comprehensive analysis of information gathered from multi-source sensors. However, limited data availability due to structural constraints poses challenges to fully characterize the system state. In this study, we introduce a data-model hybrid-driven framework based on sensor optimization placement for accurate thermal error prediction of SBSs. Firstly, a thermal hypernetwork method is developed to consider uneven temperature distribution and establish a unified information fusion model for state estimation. Secondly, based on an analysis of the rapidity and robustness, robust geodesic distance-based fuzzy c-medoid clustering with a simulated annealing algorithm (RGDFCMSA) is proposed to optimize sensor placement by minimizing the information entropy of the system. Next, uncertain parameters with estimability are selected based on SIAN and Sobol's sensitivity indicator under optimal sensor placement. Furthermore, a multilayer particle filter (MLPF) is proposed to estimate temperature fields and predict the thermal error of SBSs by fusing information from multiple sources with different fidelity. Finally, experiments under different working conditions are conducted to validate the effectiveness and accuracy of the proposed method. The result indicates that the proposed framework is capable of an accurate estimation of the global temperature field, uncertain thermal parameters and thermal errors. • A thermal hypernetwork method is proposed for unified information fusion. • A network planning algorithm RGDFCMSA is proposed for optimizing sensor layout. • MLPF is proposed for multi-fidelity and multi-physics sensor fusion. • A hybrid-driven framework is proposed for thermal error prediction. [ABSTRACT FROM AUTHOR]

A spindle-shaped sensor with temperature insensitivity based on single-mode fiber (SMF) - no-core fiber (NCF) - few-mode fiber (FMF) - NCF - SMF (SNFNS) for refractive index is proposed. An interferometer with SNFNS structure can be formed by fusing, and then the fiber can be shrunk to form a spindle shape through burning, which is known as an SNFNS spindle-shaped sensor. The introduction of NCF and curvature causes partial light transmitted in the core to enter the cladding, which results in the emergence of phase differences. The interference dips formed by modal interference have different sensitivities to the outside refractive index. The experimental results show that the maximum refractive index sensitivity of sensors is 258.5 nm/RIU in the range of 1.333–1.365. And the sensors have the characteristic of temperature insensitivity in the range of 10–70℃. Accordingly, the proposed sensors are ideal for applications in biomedicine, environment monitoring and other fields. [ABSTRACT FROM AUTHOR]

Direct ink writing (DIW) of high-temperature thin-film sensors holds significant potential for monitoring extreme environments. However, existing high-temperature inks face a trade-off between cost and performance. This study proposes a SiCN/RuO2/TiB2 composite ceramic ink. The added TiB2, after annealing in a high-temperature atmospheric environment, forms B2O3 glass, which synergizes with the SiO2 glass phase formed from the SiCN precursor to effectively encapsulate RuO2 particles. This enhances the film's density and adhesion to the substrate, preventing RuO2 volatilization at high temperatures. Additionally, the high conductivity of TiB2 improves the film's overall conductivity. Test results indicate that the SiCN/RuO2/TiB2 film exhibits high linearity from room temperature to 900 °C, high stability (resistance drift rate of 0.1%/h at 800 °C), and high conductivity (4410 S/m). As a proof of concept, temperature sensors and a heat flux sensor were successfully fabricated on a metallic hemispherical surface. Performance tests in extreme environments using high-power lasers and flame guns verified that the conformal thin-film sensor can accurately measure spherical temperature and heat flux, with a heat flux sensor response time of 53 ms. In conclusion, the SiCN/RuO2/TiB2 composite ceramic ink developed in this study offers a high-performance and cost-effective solution for high-temperature conformal thin-film sensors in extreme environments. [ABSTRACT FROM AUTHOR]

Non-contact temperature sensors utilising the fluorescence intensity ratio and the unique up-conversion (UC) luminescence of rare-earth ions have numerous benefits; however, their operational temperature range has remained limited. In this study, NaLuF4:Yb3+/Ho3+ samples were prepared by the hydrothermal method. The samples exhibited exceptional UC luminescence properties at low temperatures. The intensity of the green emission (with peak wavelengths of 540 and 546 nm) gradually decreased with increasing temperature, and the green emissions showed a unique change at low temperatures. In addition, we studied the dependence of the UC luminescence intensity on the excitation power and the variation in the decay lifetime with temperature. The experiments revealed excellent luminous performance and significantly enhanced sensitivity at low temperatures; the maximum absolute sensitivity Sa and relative sensitivity Sr of the 540 and 546 nm thermally coupled energy levels were 1.02% and 0.55% K−1, respectively. The potential temperature sensing properties of Yb3+/Ho3+-co-doped NaLuF4 makes it suitable for temperature sensing applications at temperatures as low as 30 K. This study offers a novel approach for the advancement of temperature sensing technology at low temperatures. [ABSTRACT FROM AUTHOR]

Optically active color centers in diamond and nanodiamonds can be utilized as quantum sensors for measuring various physical parameters, particularly magnetic and electric fields, as well as temperature. Due to their small size and possible surface functionalization, fluorescent nanodiamonds are extremely attractive systems for biological and medical applications since they can be used for intracellular experiments. This review focuses on fluorescent nanodiamonds for thermometry with high sensitivity and a nanoscale spatial resolution for the investigation of living systems. The current state of the art, possible further development, and potential limitations of fluorescent nanodiamonds as thermometers will be discussed here. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new run-time monitoring technique to detect hardware Trojan (HT) on working field-programmable gate array (FPGA), which is helpful for reinforcing the hardware security of IoT devices. First, we place multiple temperature sensors on FPGA and collect their value at each time interval. Then, we construct a predictive model which can estimate the distribution of sensor frequency in real-time. If the difference between the predicted value and the real one surpasses a dynamically updated threshold, an HT activation is reported. The experiment results reveal that our technique has high detection accuracy (≥ 98%), low false negative ratio (≤ 1.5%) and zero false positive ratio under various FPGA HT benchmarks. [ABSTRACT FROM AUTHOR]

Novel Bi3+/Mn4+ co-doped Y 2 MgTiO 6 dual-emitting phosphors were synthesized using a high-temperature solid-phase method. The crystal structure and luminescence properties of phosphors were systematically investigated by experimental characterization and theoretical calculation. Under excitation at 375 nm, Y 2 MgTiO 6 :Bi3+, Mn4+ phosphors exhibit two emission bands located at 410 nm and 696 nm (blue and red), which can well be matched with the absorption bands of chlorophylls a, b and phytochrome. The Y 2 MgTiO 6 : Bi3+, Mn4+ luminescence remains at 66.2 % intensity at 423 K and quantum yield is 52.06 %. Optical temperature properties of Y 2 MgTiO 6 :Bi3+, Mn4+ were investigated using fluorescence intensity ratio (FIR) analysis and were found to reach a maximum relative sensitivity of 2.93 % K−1 at 498 K. The study suggests that this material could be a potential option for indoor plant culture and optical temperature sensing. [ABSTRACT FROM AUTHOR]

Body temperature is critical indicator of human health, and its real‐time monitoring is crucial for assessing body status and disease diagnosis. In this work, a flexible temperature sensor is presented that employs a graphite/polyvinylidene fluoride (PVDF)/polyaniline composite and demonstrates a negative temperature coefficient (NTC). This sensor exhibits high sensitivity (−0.832%/ °C), rapid response time (11.05 s), and excellent linearity (R2 = 0.98). Its integration with a self‐adhesion PDMS‐PEG substrate layer ensures close skin contact, enhancing the accuracy of temperature measurements. Notably, the sensor's stability and resistance to sweat and deformation ensure continuous, reliable temperature monitoring, even during extensive exercise. This sensor thus represents a significant advancement in flexible and waterproof temperature sensing technologies. [ABSTRACT FROM AUTHOR]

This paper introduces a new high-sensitivity curvature fiber sensor based on a miniature two-path Mach–Zehnder interferometer (MTP-MZI). The sensor is fabricated by coupling and fusing the multimode fiber (MMF) with the single-mode fiber (SMF) using arc fusion technology (AFT), resulting in a centimeter-level two-path MZI structure. The sensor represents an innovative approach to MZI coupling technology, which reduces device size, simplifies manufacturing, and lowers costs. In curvature-sensing experiments, the MTP-MZI sensor achieves a maximum curvature sensitivity of −96.70 dB/m−1 in the curvature range of 0.0418 m−1 to 0.0888 m−1, which is an extremely high sensitivity among intensity-modulated curvature sensors. Additionally, temperature-sensing measurements of the MTP-MZI sensor show a maximum temperature sensitivity of 212 pm/°C in the range of 30 °C to 70 °C, which is low temperature sensitivity and solves the cross-sensitivity problem. Thanks to the miniature two-path structure of the MTP-MZI, it provides a new perspective for developing multidimensional and multiparameter measurement methods in MZI fiber sensors. [ABSTRACT FROM AUTHOR]

This work proposes a simple and affordable technology for the manufacturing of a miniature end-face fiber-optic temperature sensor based on a Fabry–Perot interferometer formed from a transparent UV-curable resin. For the manufactured working prototype of the sensor, the sensitivity and operating temperature range were determined, and the methods for their enhancement were proposed. Due to its small size, the proposed type of sensor can be used in high-precision and minimally invasive temperature measurements, in biology for microscale sample monitoring, and in medicine during operations using high-power lasers. A microwave photonic method is proposed that enables the interrogation of the sensor without using an optical spectrum analyzer. [ABSTRACT FROM AUTHOR]

In this paper we present the principle of operation, fabrication and performance of a phosphorescent optical-fiber quasi-distributed sensor with contactless smartphone interrogation. An array of short strong corrugated long-period gratings (C-LPG) is used as a platform to spatially locate and to excite the phosphors whose time responses are temperature-dependent. The C-LPG array was fabricated using a pulsed CO2 laser. The quasi-distributed sensing array is excited by a UV LED and the normalized differential rise/decay time response measured by a smartphone is used as a measure of the temperature. The sensing spots have a volume smaller than 0.5 μL, can be separated by several millimeters to several meters and the interrogation can be simultaneous or in a sequence. The response and the sensitivity to temperature have been measured. The sensing array has been shown to measure abrupt and gradual temperature changes in space as well as time-dependent processes in the 0 °C to 100 °C range and with a measurement time of 1 s. [ABSTRACT FROM AUTHOR]

A vector curvature and temperature sensor based on an in-fiber hybrid microstructure is proposed and experimentally demonstrated. The proposed scheme enables the dimensions of the Fabry–Perot and Mach–Zehnder hybrid interferometer to be adjusted for the formation of the Vernier effect by simply changing the length of a single optical fiber. The sensor is fabricated using a fiber Bragg grating (FBG), multimode fiber (MMF), and a single-hole dual-core fiber (SHDCF). The sensor exhibits different curvature sensitivities in four vertical directions, enabling two-dimensional curvature sensing. The temperature and curvature sensitivities of the sensor were enhanced to 100 pm/°C and −25.55 nm/m−1, respectively, and the temperature crosstalk was minimal at −3.9 × 10−3 m−1/°C. This hybrid microstructure sensor technology can be applied to high-sensitivity two-dimensional vector curvature and temperature detection for structural health monitoring of buildings, bridge engineering, and other related fields. [ABSTRACT FROM AUTHOR]

Bridge cables exhibit low damping characteristics and are susceptible to external excitations, leading to random vibrations. Therefore, a cable cross‐tie triboelectric‐electromagnetic hybrid generator triggered by vibrations in bridge cables (CCT‐TEHG) is proposed. The CCT‐TEHG enhances the natural frequency of the cables by connecting adjacent cables, thereby preventing low‐frequency resonance. The device connects adjacent bridge cables to increase the natural frequency, preventing low‐frequency resonance. Comprising triboelectric nanogenerators (TENGs) and electromagnetic generators (EMG), the CCT‐TEHG effectively broadens the frequency range for energy harvesting, capturing vibrational energy from bridge cables in cable‐stayed bridges. The TENG module in CCT‐TEHG features a soft‐contact design, incorporating rabbit fur to supplement charges and enhance output density. This design also avoids direct material contact between generator units, improving operational durability. The experimental results show that the maximum output voltage and current of the TENG and EMG modules can respectively reach up to 270 V, 13 V, and 5.2 µA, 18 mA, and peak power to 2.04 mW, 10 mW. The CCT‐TEHG can function as a power source, sufficient to power 303 light‐emitting diodes (LEDs) or a 20 mW temperature and humidity sensor. Therefore, CCT‐TEHG has good application prospects in the field of bridge cable vibration energy harvest. [ABSTRACT FROM AUTHOR]

Water air cooler is a process that uses an evaporative system. In its first generation, there was no temperature sensor, and its fan was turned by an electric motor in an open loop system with a fixed speed. As well, the water's flow and level in the tank are governed by a mechanical system, which is generally a floating ball attached to a shaft. In order to ameliorate this classical system with more advantages and performances, many ideas are included in subsequent generations such the integration of embedded systems, intelligent control and components of manufacturing materials. In this paper, the current study aims to integrate an intelligent system, which is the neural networks by using R language to give a smart decision model to command relays switching dedicated to control the electric motors, where the first one is tied up with a fan and the other to an electro-pump. The HCSR04 ultrasonic and DHT11 sensors supervise the two desired parameters control, water level in the tank and the outside temperature successively. [ABSTRACT FROM AUTHOR]

The efficient use of resources can contribute to the eradication of poverty and the reduction of environmental impact. Therefore, the use of recycled waste materials is desirable since it helps in the reduction of pollution. Some devices, such as interferometric optical sensors, can be implemented with this type of materials. In addition, optical sensors play an important role in the Internet of Things since they can be used to implement networks that simultaneously monitor several physical parameters. A problem that limits the measurement range of interferometric optical sensors is the 2π ambiguity. In this work, it is presented that the nominal measurement range of this type of sensor can be increased considerably by applying machine learning algorithms. In this sense, the kernel ridge regression (KRR) method is applied to the signals of a temperature sensor that is based on a tunable optical two-layer interferometer. Here, it is shown that this interferometric sensor can be fabricated with recycled waste materials (a polished stainless-steel plate, a single-mode fiber, a syringe needle, and epoxy clay), and the fabrication process is described. Furthermore, it is demonstrated that when KRR is used, the measurement range is increased at least two and a half times compared with that reached with traditional methods, and the temperature can be estimated with a root mean square error of 1.97 × 10-5 ℃. [ABSTRACT FROM AUTHOR]

Mechanically deformable flexible temperature sensors are being used to fabricate next-generation smart electronics, but improving their high-temperature application range is still a major challenge. In this work, in pursuit of excellent performance, a series of Mn–Ni–O ultrathin flexible thermal thin films with dual-phase structure were successfully prepared by magnetron sputtering using the bias voltage adjustment method. The interactions of grain density, ionic valence and phase structure on the performance of high-temperature NTC are emphasized. By overcoming the significant drawbacks of the flexible thermal films such as poor stability and narrow temperature range under high temperature conditions, excellent thermal performance with a wide temperature range from 200 °C to 600 °C and a resistance drift rate as low as 1.5 % has been achieved. This opens up innovative prospects for the design and application of flexible high-temperature thermal materials. [ABSTRACT FROM AUTHOR]

NiSi–NiCr thin film thermocouples (TFTCs) have significant application value as contact temperature sensors in cutting temperature measurements owing to their fast response and negligible volume. However, due to the relatively high chemical activity of Ni-based alloys, high-temperature oxidation strongly affects the operational reliability of NiSi–NiCr TFTCs. In this respect, depositing an anti-oxidation coating onto the surface of NiSi–NiCr TFTCs is considered an effective way to protect them in high-temperature environments. In this study, NiSi and NiCr films were deposited on cemented carbides and annealed at 200 °C–600 °C in air. Scanning electron microscope, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, and four-probe resistivity tests were used to characterize the microstructure and resistivity of NiSi and NiCr film. Then SiN x O y films were deposited onto the NiSi and NiCr films and compared with uncoated samples after annealing at 600 °C. The effect of SiN x O y films on the thermal stability and thermoelectric output of NiSi–NiCr TFTCs was investigated. The results show that the NiSi film was partially oxidized at 200 °C and entirely oxidized when the temperature exceeded 400 °C. The completely oxidized NiSi films had evident defects and cracks, and the resistivity increased by a factor of over 1000. The NiCr film could not be completely oxidized at 600 °C, which is attributed to the formation of Cr 2 O 3 as an external oxide barrier layer. Below 600 °C, SiN x O y films could effectively protect NiSi and NiCr films from oxidation. Thus, the addition of SiN x O y film increases the maximum temperature at which NiSi–NiCr TFTCs can be used. [ABSTRACT FROM AUTHOR]

In this paper, the new non-integer-order state space model of heat processes in a one-dimensional metallic rod is addressed. The fractional orders of derivatives along space and time are not exactly known, and they are described by intervals. The proposed model is the interval expanding of the state space fractional model of heat conduction and dissipation in a one-dimensional metallic rod. It is expected to better describe reality because the interval order of each real process is difficult to estimate. Using intervals enables describing the uncertainty. The presented interval model can be applied to the modeling of many real thermal processes in the industry and building. For example, it can describe the thermal conductivity of building walls. The one-dimensional approach can be applied because only the direction from inside to outside is important, and the heat distribution along the remaining directions is uniform. The paper describes the basic properties of the proposed model and supports the theory via simulations in MATLAB R2020b and experiments executed with the use of a real experimental laboratory system equipped with miniature temperature sensors and supervised by PLC and SCADA systems. The main results from the paper point out that the uncertainty of both fractional orders impacts the crucial properties of the model. The uncertainty of the derivative along the time affects only the dynamics, but the disturbance of the derivative along the length disturbs both the static and dynamic properties of the model. [ABSTRACT FROM AUTHOR]

Mass concrete is widely used in large-scale projects, including metro upper cover structures, water conservancy dams, and heavy equipment foundations, among others, necessitating the process of health monitoring in mass concrete construction. The development of reliable and simple strength-monitoring methods for mass concrete is challenging because the inner temperature of mass concrete is high and changes a lot. This study proposes a strength-monitoring approach for mass concrete using barium titanate–bismuth ferrite/polyvinylidene fluoride (BT–BFO/PVDF) nanocomposite piezoelectric sensors, wherein the new sensors are embedded as actuators and sensors in mass concrete. The stress wave generated by the BT–BFO/PVDF piezoelectric sensors is used to monitor the specimen's strength for 28 days. The piezoelectric voltage received by the sensors in mass concrete is analyzed. The experimental results indicate that the signal received by the BT–BFO/PVDF sensors is not easily affected by the internal temperature of mass concrete compared with that of the traditional PVDF piezoelectric sensors. The signal parameters sensitive to concrete strength variation and the change trend of concrete strength are closely related to the piezoelectric voltage. Therefore, the proposed approach using BT–BFO/PVDF nanocomposite piezoelectric sensors is efficient (error < 10%) in mass concrete monitoring. Moreover, the monitoring results do not need temperature compensation. The physical meaning of the obtained strength prediction formula is proposed. An experimental system based on PVDF dynamic strain-sensing characteristics is established. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of a highly accurate smart temperature sensor designed in 65 nm CMOS technology. The sensor exhibits a ±0.15 °C (3σ) error across a wide temperature range from −40 °C to 125 °C, catering to diverse application needs. Leveraging advanced CMOS technology, the sensor employs an adaptive decimation filter that allows us to control the conversion time, ensuring that the accuracy of the conversion is maintained even in challenging conditions. The proposed sensor architecture integrates advanced techniques for temperature sensing for improved accuracy and reliability. Through meticulous circuit design and the usage of dynamic element matching, chopping, and calibration/trimming, the sensor demonstrates exceptional performance characteristics, making it suitable for various industrial, automotive, and consumer electronics applications demanding high precision temperature monitoring. [ABSTRACT FROM AUTHOR]

A colorimetric sensing platform based on carboxymethyl cellulose-silver nanoparticles (CMC-AgNPs) metallogel was proposed to monitor the temperature history and quality of perishable products stored at low temperature. The carboxymethyl cellulose (CMC) metallogel, fabricated in the presence of Ag+, incorporates ionic crosslinking of biopolymers, complexation between reactants, and subsequent in situ synthesis of AgNPs, which are designed to lead the color transition of metallogel from colorless to dark brown depending on temperature and time. The mechanical and structural properties of metallogels and AgNPs were characterized by rheology, XRD, and FT-IR. Color changes associated with temperature, time, and metal ion precursors were examined by UV–visible spectroscopy and colorimetry. The longer the exposure time to thermal stress condition such as room temperature (25 °C) or high temperature (60 °C), the deeper the color of metallogel. The CMC-AgNPs metallogel-based sensor provides an efficient, safe way to track temperature history and assess perishable products' quality, crucial for the safe distribution of food, vaccines, and medicines. This cost-effective and reliable visual sensor minimizes spoilage and health risks by enabling accurate temperature monitoring without the need for complicated equipment. [ABSTRACT FROM AUTHOR]

AbstractA high-sensitivity temperature sensor based upon an optical fiber Fabry-Perot interferometer (FPI) filled with polydimethylsiloxane (PDMS) is reported that employed a single mode fiber (SMF) and a hollow core fiber (HCF) to enhance the sensitivity. The sensing characteristics were investigated from 20 °C to 40 °C. The experimental results demonstrate that the sensor is sensitive to temperature due to the high thermal optical coefficient (TOC) and high thermal expansion coefficient (TEC) of PDMS, achieving a high sensitivity of 2.155 nm/°C. The designed sensor shows great potential for high-precision temperature sensing applications due to its high sensitivity, compact structure, and simple preparation. [ABSTRACT FROM AUTHOR]

Microelectromechanical systems (MEMSs) are microdevices fabricated using semiconductor-fabrication technology, especially those with moving components. This technology has become more widely used in daily life, e.g., in mobile phones, printers, and cars. In this review, MEMS sensors are largely classified as physical or chemical ones. Physical sensors include pressure, inertial force, acoustic, flow, temperature, optical, and magnetic ones. Chemical sensors include gas, odorant, ion, and biological ones. The fundamental principle of sensing is reading out either the movement or electrical-property change of microstructures caused by external stimuli. Here, sensing mechanisms of the sensors are explained using diagrams with equivalent circuits to show the similarity. Examples of multiple parameter measurement with single sensors (e.g. quantum sensors or resonant pressure and temperature sensors) and parallel sensor integration are also introduced. [ABSTRACT FROM AUTHOR]

Changes in volcanic activity are frequently correlated with geochemical changes in crater lake waters. Volcanologists employ periodic surveys of the volcano crater lake which include pH and temperature monitoring. Due to the exposure of volcanologists to volcanic hazards, a robotic remote monitoring system was implemented in this study. A ground robot with a tethered sensing device, launcher, and retrieval system is investigated for pH and temperature real-time data sensing considering the challenging conditions of Taal Crater Lake in the Philippines. The sensing device has a tethering system attached to two mechanisms: the launcher and the retrieval systems. From the test experiments, it was found that the system can project the sensing device for a horizontal distance of 3 meters and retrieve it smoothly. The pH and temperature sensors in the device were calibrated and demonstrated acceptable levels of error and reliability. An actual test on a lake environment was implemented. The remote-controlled ground robot can navigate the sensing device to the required default position near the lake shore and effectively launch the sensing device into the water. Moreover, the tethered sensing device successfully performed real-time pH and temperature data sensing of the water and was securely retrieved from the water back to the ground robot. After the real-time data were assessed and validated, the average errors for the temperature and pH data were only 0.44% and 1.8%, respectively. [ABSTRACT FROM AUTHOR]

Acceptor–donor–acceptor (A–D–A) molecular rotors have drawn substantial attention for their applications in monitoring temperature variations within cellular microenvironments, biomimetic photocatalysis, and bioimaging. In this study, we have synthesized two novel rotor molecules, NBN1 and NBN2, by incorporating benzodithiophene (BDT) as the donor core and naphthalic anhydride/naphthalimide (NA/NI) moieties as acceptors using Pd‐catalyzed Stille coupling reactions. These molecules exhibited distinct charge transfer (CT) behavior in both their absorption and emission spectra and displayed prominent emission solvatochromism. Notably, NBN1 exhibited better CT properties among the two molecules. Moreover, these A–D–A molecular rotors demonstrated remarkable sensitivities of their emission spectra toward solvent polarities and temperatures. Rotors NBN1 and NBN2 showed positive temperature coefficients with internal temperature sensitivities of 0.34% °C−1 and 0.13% °C−1 in chloroform, respectively, and thus hold significant promise for detecting temperature variations in cellular microenvironment. Furthermore, we have modeled these molecules with graphitic carbon nitride (g‐C3N4) to form composite systems and performed theoretical calculations to obtain valuable insights into their charge transfer behavior. Theoretical results suggested that these molecules have the potential to efficiently sensitize and modulate the band gap of g‐C3N4 and show potential for diverse photocatalytic applications. [ABSTRACT FROM AUTHOR]

The steep increase in carbon dioxide (CO2) emissions has created great concern due to its role in the greenhouse effect and global warming. One approach to mitigate CO2 levels involves its application in specific technologies. In this context, CO2 can be used for a more sustainable synthesis of polycarbonates (CO2-PCs). In this research, CO2-PC films and composites with multiwalled carbon nanotubes (MWCNTs, ranging from 0.2 to 7.0 wt.%) have been prepared to achieve more sustainable multifunctional sensing devices. The inclusion of the carbonaceous fillers allows for the electrical conductivity to be enhanced, reaching the percolation threshold (Pc) at 0.1 wt.% MWCNTs and a maximum electrical conductivity of 0.107 S·m−1 for the composite containing 1.5 wt.% MWCNTs. The composite containing 3.0 wt.% MWCNTs was also studied, showing a stable and linear response under temperature variations from 40 to 100 °C and from 30 to 45 °C, with a sensitivity of 1.3 × 10−4 °C−1. Thus, this investigation demonstrates the possibility of employing CO2-derived PC/MWCNT composites as thermoresistive sensing materials, allowing for the transition towards sustainable polymer-based electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal complexes of copper subgroup metals are actively studied objects for temperature sensors. Their luminescence arising from the 3ILCT, 3MLCT or 3CC excited states is characterized by emission in all ranges of visible spectra and high quantum yields. Due to the ability of the complexes to emit in a dual band mode, these complexes are attractive for the temperature sensing in the ratiometric mode. Dual emission of complexes is usually susceptible of the irregular changes in intensity of two emission bands during the temperature changes. This is an important and necessary property for the utilization of phosphors as ratiometric thermometers. The structures and emission properties of gold(i) and copper(i) complexes are considered with the aim to demonstrate the possibility to apply such complexes as ratiometric molecular luminescent thermometers for the remote control of the object's temperature. [ABSTRACT FROM AUTHOR]

Initially, indium doped SnO2 (In–SnO2) nanoparticles were synthesised, using co-precipitation technique which then utilised to produce Indium doped SnO2/Polyaniline (In–SnO2/PANi) nanocomposites using in-situ polymerisation. The as-synthesised nanocomposites were found to be selective towards sensing of dimethyl methyl phosphonate (DMMP) gas. The influence of doping on structural, optical, thermal stability, morphology and shape were investigated using XRD, FT-IR, FE-SEM, XPS and EDS. The concentration of doping was optimised for maximum gas response. Furthermore, the gas sensing experiment was executed at various humidity levels. 9@ISP nanocomposites show maximal response (85.1%) as compared to pure PANi, pure SnO2, 0@ISP, 3@ISP, 6@ISP, 12@ISP and 15@ISP nanocomposites. For 10 ppm of DMMA gas, response and recovery times were 33.5 and 27.1 s, respectively. As the DMMP gas concentration rises from 1 to 25 ppm, reaction to gas sensors was found to be increased. DMMP gas shows enhanced selectivity towards 9@ISP nanocomposite as compared to the other gases (xylene, toluene, benzene, and acetonitrile gas). The reproducibility study of 9@ISP nanocomposite was performed for 30 days and found to be impressive. [ABSTRACT FROM AUTHOR]

Tri-doped phosphor YNbO4:Er3+/Tm3+/Yb3+ was prepared by solid-state reaction method. The XRD and SEM results reveal that the product is a monoclinic phase of YNbO4 with high crystallinity and the particles presenting grains with well-defined boundaries with average size is about 1–5 μm. The temperature-dependent luminescence is investigated with 980 nm laser excitation, whereas temperature sensing behaviour was studied in the range of 300–500 K based on Stark sublevels 1G4(a)/1G4(b) (Tm3+), thermal coupling levels 2H11/2/4S3/2 (Er3+) and non-thermal coupling levels 4F9/2 → 4I15/2 (Er3+) /3F2 → 3H6 (Tm3+), 2H11/2 → 4I15/2 (Er3+) / 4F9/2 → 4I15/2 (Tm3+) and 4S3/2 → 4I15/2 (Er3+) /3F2 → 3H6 (Tm3+), utilizing fluorescence intensity ratio (FIR) technique. It is worth highlighting that 1G4(a)/1G4(b) ratio as is not much employed in thermometry. Regarding, NTCL 3F2/1G4(b) pair exhibited the highest absolute sensitivity (SA) is about 110.2 × 10− 3 K− 1 at 500 K, whereas NTCL 3F2/4F9/2 pair presented the highest relative sensitivity (SR) is 2.1% K− 1 at 339 K. Meanwhile, the temperature-dependent emission colours are discussed in detail. High sensitivity indicates that YNbO4:Er3+/Tm3+/Yb3+ white-light phosphor can be used in non-contact temperature sensors applications. [ABSTRACT FROM AUTHOR]