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Passive temperature sensing systems based on the Internet of Things (IoT) present an efficient, reliable, and convenient solution for temperature monitoring with extensive application prospects and market value. This paper introduces a passive, battery-free, chipless, metasurface temperature sensing tag. The key insight is that the sensing tag uses vanadium dioxide () to solve the problems of measuring distance, large size, and high cost related to active devices. The sensing tag fabricated with tungsten-doped powder demonstrated a significant variation in the reflection magnitude within the temperature range of 34–42 °C. It was achieved through coating, sintering, metasurface design, and ion beam etching. Experimental results showed that the square resistance of the prepared coating decreased from 1003 to 90 as the temperature increased from 34 to 42 °C. Additionally, the reflection magnitude of the tag significantly increased with the temperature decrease in the 3.5–5.27 GHz frequency band. These results indicate that the passive temperature sensing tags can achieve rapid and accurate temperature sensing within the 34–42 °C range. [ABSTRACT FROM AUTHOR]

A series of Y 2 MoO 6 :0.01Er3+/0.09 Yb3+ upconversion phosphors doped with different concentrations of Li + ions (0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 mol) were prepared by the high temperature solid phase reaction method, and their physical phase structures and upconversion luminescence were analyzed. At the excitation wavelength of 980 nm, the addition of Li+ sharply increased the upconversion luminescence intensity. With the increase of Li+ ion content, the luminescence intensity first increases and then decreases. When the doping amount reaches 0.25 mol, the luminescence intensity reaches the maximum, and the sample emits green light in the two-photon process. Y 2 MoO 6 :0.01Er3+/0.09 Yb3+/0.25Li + exhibits excellent temperature sensing properties. Its absolute sensitivity S a reaches up to 0.012 K-1, the relative sensitivity S r is 0.017 K-1 and the measurement error δ T is less than 0.3 K at room temperature. Its temperature sensing performance is far superior to similar materials. In addition, Judd-Ofelt theory calculations revealed that in comparison with Y 2 MoO 6 :0.01Er3+/0.09 Yb3+, its Ω 2 increased from 0.56 × 10−20 cm2 to 3.68 × 10−20 cm2, and the spectroscopic quality factor Ω 4 /Ω 6 ratio reached 4.09, which is much higher than that of the other fluorescent materials. The main reason is that Li + replaces the Y3+ ion lattice site, causing lattice distortion and reducing the lattice symmetry around the active ion. The increase in asymmetry increases the possibility of spontaneous radiative transitions. It is shown that the prepared upconversion luminescent materials have potential applications in the field of solid-state lasers and optical sensing. [ABSTRACT FROM AUTHOR]

Through conventional solid-state sintering process, PbNb2O6:Yb3+, Ln3+ (Ln3+=Er3+/Ho3+) ceramics have been fabricated. The structural information of synthesized ceramics was obtained via X-ray diffraction. Scanning electron microscopy was utilized to investigate their morphological properties. The investigation of upconversion photoluminescence properties of the synthesized ceramics was conducted by analyzing upconversion emission spectra upon excitation with 980 nm light. Power dependence studies confirmed the presence of two-photon absorption processes in both PbNb2O6:Yb3+, Er3+ and PbNb2O6:Yb3+, Ho3+ ceramics. Temperature-dependent experiments from 303 K to 513 K demonstrated significant variations in emission intensities and fluorescence intensity ratios (FIR), enabling the assessment of temperature changes. The absolute sensitivity of PbNb2O6 ceramic co-doped with Yb3+, Er3+ ions reached its maximum value of 0.0056 K-1 at 513 K, while the maximum relative sensitivity of 0.697% K-1 was recorded at 339 K. For PbNb2O6 ceramic co-doped with Yb3+, Ho3+ ions, the maximum values of absolute and relative sensitivities were 0.048 K-1 and 0.8% K-1 at 513 K and 473 K, respectively. These results highlight the potential applications of PbNb2O6:Yb3+, Ln3+ (Ln3+=Er3+/Ho3+) ceramics in advanced temperature sensing based on photoluminescence. [ABSTRACT FROM AUTHOR]

In recent years, people have higher requirements for temperature measurement with the development of optical temperature measurement. Meanwhile, the emission intensity of most fluorescent materials is quenched by thermal effects as the temperature rises, making it challenging to meet the specifications of fluorescent materials employed in the field of pyrometry. In this work, the pure phase of Yb3+/Er3+ ions co-doped Sc 2 W 3 O 12 phosphor was successfully prepared. Sc 2 W 3 O 12 : Yb3+, Er3+ samples showed strong green emission and weak red emission. The optimal doping concentrations of Yb3+ and Er3+ ions are 0.3 and 0.02, respectively. The potential upconversion luminescence (UCL) mechanism was investigated by analyzing the UCL spectra, downshift emission spectra and power dependence spectra of Yb3+/Er3+ ions co-doped Sc 2 W 3 O 12. The upconversion emission excitation path is mainly through Er3+ ions from 4I 11/2 absorption photon excitation to 4F 7/2 energy level, then the photons of 4F 7/2 relaxes to green and red emission energy levels and returns to ground state for emitting green and red light. In addition, according to the UCL green light intensity increasing with temperature, it serves as an optical temperature sensor. The temperature sensitivity of the sample was explored in the temperature range of 298 K–673 K. This study provides new materials and ideas for non-contact temperature sensing. [ABSTRACT FROM AUTHOR]

The redshift of the charge transfer band (CTB) edge of phosphor induced by temperature rise is pervasively accompanied by antithermal quenching. Accordingly, exploring the mechanism of the CTB redshift is thus not only propitious for optimizing the sensitivity of optical thermometry but also tenders a new idea for the design of antithermal quenching phosphors. Herein, a family of YP 1-x V x O 4 :Eu3+ phosphors were designed via the V5+/P5+ ion substitution strategy. With the increase of the V5+ ratio, the relative integral intensity of the 5D 0 →7F 2 transition multiplies from 1.25 to 28.67 times under CTB edge excitation. Moreover, by Gaussian fitting, the reduction degree of vanadate band gap energy 1E (1T 1)→1B 2 (1T 2), 1A 2 (1T 1)→1B 2 (1T 2) increased from 0.122 eV and 0.065 eV to0.162 eV and 0.083 eV, respectively, in the range of 303–523 K. Both reveal an enhance in redshift of the excitation spectra. The decrease of charge transfer state (CTS) energy level and the alteration of photoelectron thermal population are two mechanisms that induce CTB redshift. Specifically, the decrease of the CTS level is dominant in the YPO 4 :Eu3+ sample, and the thermal population of the higher vibrational levels of the VO 4 3−ground state is dominant in the presence of a tiny amount of V5+ doping. In addition, according to the experimental phenomenon, a dual-mode temperature sensing scheme based on excitation intensity ratio (EIR) and single band ratiometric (SBR) is proposed. Y 0.9 P 0.1 V 0.9 O 4 :0.1Eu3+ achieves a maximum sensitivity of S r-max = 4.040 % K−1 and a minimum temperature determination uncertainty of δT = 0.124 K at 323 K, which excellent performance indicates that this is a promising non-contact optical thermometer. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The design of active and inert shell in NaYF 4 :Yb,Er @ NaYF 4 UCNPs exhibits the superior luminescence under 980 nm excitation. • NaYF 4 @NaYF 4 :Yb,Nd,Er core–shell UCNPs demonstrate optimized luminescence under 808 nm laser excitation because the inert core can bring the activators into closer proximity with each other. • NaYbF 4 as an active layer improves temperature sensitivity with S r = 1.12 %K−1 under 808 nm excitation. Research on the core–shell design of rare earth-doped nanoparticles has recently gained significant attention, particularly in exploring the synergistic effects of combining active and inert shell layers. In this study, we successfully synthesized 8 types of spherical core–shell Na-based nanoparticles to enhance the efficiency of core–shell design in upconversion luminescence and temperature sensing through the strategic arrangement of inert and active layers. The most effective upconversion luminescence was observed under 980 nm and 808 nm laser excitation using NaYF 4 inert shell NaYF 4 :Yb3+, Er3+@ NaYF 4 and NaYF 4 @ NaYF4:Yb3+, Nd3+ core–shell nanostructures. Moreover, the incorporation of the NaYbF 4 active shell structure led to a significant increase in relative sensitivity in ratio luminescence thermometry. Notably, the NaYF 4 :Yb3+, Nd3+, Er3+@ NaYbF 4 core–shell structure demonstrated the highest relative sensitivity of 1.12 %K−1. This research underscores the crucial role of inert shell layers in enhancing upconversion luminescence in core–shell structure design, while active layers play a key role in achieving high-sensitivity temperature detection capabilities. [ABSTRACT FROM AUTHOR]

Rice husk is usually generated as waste in large quantities but yet to be optimally utilized. Due to the pollution effects associated with poor approach prevalently adopted for its disposal, valorizing it into economical and sustainable material for building construction is a necessary option to provide solution for future generation. In this research, separate dry mortars were prepared using cement grades 32.5R and 42.5N and the influence of rice husk ash (RHA) inclusion on their electrical characteristics was investigated. The materials used were batched by volume and the RHA was utilized as a partial substitute for cement at 10 % level. All the samples were cured for 21 days and then allowed to dry completely prior to the tests implementation. The results showed decrease in electrical resistance with temperature (ranging from 20oC to 50oC) due to incorporation of the RHA. Though samples with the RHA content possessed ability to act as smart mortars for temperature monitoring/sensing, utilization of cement grade 42.5N ensured a better performance. By utilizing rice husks in such undertakings, their associated disposal problems could be tackled and construction of inexpensive but sustainable building with large temperature sensing capability could be enhanced.

Understanding how cells sense temperature is a fundamental question in biology and is pivotal for the evolution of life. In numerous organisms, temperature is not only sensed but also generated due to cellular processes. Consequently, the mechanisms governing temperature sensation in various organisms have been experimentally elucidated. Extending upon others’ proposals and demonstration of protein- and nucleic acid-based thermosensors, and utilizing a colonial India ‘punkah-wallahs’ analogy, I present my rationale for the necessity of temperature sensing in every organelle in a cell. Finally, I propose temperature-sensing riboceptors (ribonucleic acid receptors) to integrate all the RNA molecules (mRNA, non-coding RNA, and so forth) capable of sensing temperature and triggering a signaling event, which I call as thermocrine signaling. This approach could enable the identification of riboceptors in every cell of almost every organism, not only for temperature but also for other classes of ligands, including gaseous solutes, and water.

This work presents a continuous volumetric indoor air temperature measurement scheme using PMUTs (piezoelectric micromachined ultrasonic transducers). Advancements as compared to state-of-art works include: (1) 'volumetric' temperature monitoring instead traditional 'pointwise' temperature information; (2) accurate temperature readings spanning an operational distance of 5 m as validated by a commercial thermometer for 3 days; and (3) capable of detecting global average temperature and local temperature events by installing networked/grid PMUT pairs. This innovative sensing technique could be applicable for the precision control of future building/living environments.

An "turn-on" polymer nanothermometer based on aggregation induced emission is applied for intracellular temperature sensing. [Display omitted] • The polymer nanothermometer shows TICT and AIE properties. • The nanothermometer exhibits "turn on" fluorescence in response to temperature. • It is applied for temperature sensing of lysosomes in A549 cells. Temperature measurements at the nanoscale facilitate the understanding of physiological processes related to heat in cells. Herein, we prepare a tetraphenylethylene-functionalized fluorophore (TPPEBr) with dual characteristics of twisted intramolecular charge transfer (TICT) and aggregation induced emission (AIE). It is polymerized with a thermo-responsive unit NIPAM to construct a fluorescent polymer nanothermometer (PNIPAM-TPPEBr). The phase transition behavior of PNIPAM from dispersed chains to dense spheres in aqueous media promotes the aggregation of TPPEBr fluorophores, which makes the fluorescence of PNIPAM-TPPEBr enhance with increasing temperature. Furthermore, the phase transition of PNIPAM is accompanied by a significant decrease in the polarity of the microenvironment, resulting in a blue shift in the emission wavelength of TPPEBr. Varying the ratio of NIPAM and TPPEBr can regulate the thermo-responsiveness of PNIPAM-TPPEBr in the physiological temperature range (31–38 °C), and the maximum relative thermal sensitivity reaches 13.2 % °C−1. The thermo-responsive performance of this nanothermometer is independent of the intracellular microenvironment, and it is successfully applied in the temperature imaging of A549 cells. Under the stimulation of ionomycin and oxidative phosphorylation inhibitor, the cell temperature increased by ca. 1.5 °C and ca. 1.0 °C, respectively. [ABSTRACT FROM AUTHOR]

Abstract The accurate characterization of local magnetic fields and temperature is vital for the design of electronic systems. To meet this imperative, we present a novel non-contact approach for simultaneous quantitative magnetic field imaging and temperature sensing using magnetooptics and a bismuth-doped yttrium iron garnet film with out-of-plane anisotropy. For the direct signal quantification, a Stokes polarization camera is employed in a conventional magnetooptical microscope. The magnetization in the garnet is modulated with an external magnetic field to continuously image the Faraday rotation at four distinct points along the saturating magnetization loop. The method enables sensing of the magnetooptical signal in saturation, the magnetooptical susceptibility, the temperature, and self-calibrated driftfree imaging of the out-of-plane magnetic field component. A spatial resolution of magnetic field in the micrometer range with millisecond exposure time is demonstrated. The method is verified by analyzing the stray magnetic field distribution of electrical current in a wire simultaneously to the Joule heating induced by the applied current.

The surge in demand for 3D MOSFETs, such as FinFETs, driven by recent technological advances, is explored in this review. FinFETs, positioned as promising alternatives to bulk CMOS, exhibit favorable electrostatic characteristics and offer power/performance benefits, scalability, and control over short-channel effects. Simulations provide insights into functionality and leakage, addressing off-current issues common in narrow band-gap materials within a CMOS-compatible process. Multiple structures have been introduced for FinFETs. Moreover, some studies on the fabrication of FinFETs using different materials have been discussed. Despite their potential, challenges like corner effects, quantum effects, width quantization, layout dependencies, and parasitics have been acknowledged. In the post-planar CMOS landscape, FinFETs show potential for scalability in nanoscale CMOS, which leads to novel structures for them. Finally, recent developments in FinFET-based sensors are discussed. In a general view, this comprehensive review delves into the intricacies of FinFET fabrication, exploring historical development, classifications, and cutting-edge ideas for the used materials and FinFET application, i.e., sensing. [ABSTRACT FROM AUTHOR]

Upconversion luminescence presents obvious advantages in optical temperature sensing, nevertheless the application in complex scenarios is limited by luminescence thermal quenching. Herein, NaYS 2 :Yb3+,Nd3+ phosphors are synthesized by the solid-gas reaction method and used for temperature sensing. A series of emissions for Nd3+ from visible to near-infrared region are achieved based on energy transfer from Yb3+ to Nd3+ under 980 nm excitation. With elevating the temperature, significant thermal enhancement effect of nearly three orders of magnitude is detected in near-infrared emission of 4F 7/2 → 4I 9/2 , which is attributed to phonon-assisted energy transfer of Yb3+→Nd3+ and the corresponding thermal population effect. The thermal behaviors of thermally coupled energy levels for 4G 7/2 /2G 9/2 and 4F 7/2 /4F 5/2 in NaYS 2 :Yb3+,Nd3+ are evaluated by luminescence intensity ratio technique. Remarkably, the optical thermometer based on the enhanced emission of 4F 7/2 /4F 5/2 shows excellent temperature measurement performance, which is expected to be applied in wide-temperature-range and highly-sensitive temperature sensing. These results not only provide a pathway to realize high performance temperature sensing, but also heighten the understanding of UC emission thermal enhancement. [ABSTRACT FROM AUTHOR]

Cryolite-type materials have advantages of low phonon energy, easy rare-earth ion doping, and stable physicochemical properties, and they are considered ideal matrices for up-converting luminescent materials. In this paper, a series of K 3 LuF 6 :Er3+,Yb3+ up-converting materials with cryolite structure were prepared for the first time by high-temperature solid-phase method. The compositions, structures and luminescent properties were systematically characterized by X-ray powder diffractometry (XRD), field emission scanning electron microscopy (SEM) and fluorescence spectroscopy (PL). Under 980 nm excitation, the sample emission spectra mainly consisted of green and red emission bands with peaks at 525, 546 and 662 nm, corresponding to the 2H 11/2 -4I 15/2 , 4S 3/2 -4I 15/2 and 4F 9/2 -4I 15/2 electron transitions of Er3+, respectively. In addition, the temperature sensing characteristics of two thermally coupled energy levels (2H 2/11 and 4S 3/2) were studied based on the fluorescence intensity ratio (FIR) technique in the range of 79–579 K. All the results show that K 3 LuF 6 :Er3+/Yb3+ up-converting luminescent materials have excellent temperature sensing performance in the ultra-wide temperature range and have broad application prospects in the field of temperature sensing. [ABSTRACT FROM AUTHOR]

Light and temperature are the driving forces in plant development and growth. Specific photoreceptors provide the ability to sense and interpret light and temperature to regulate growth. Under the limited light conditions in most sports stadiums, natural grasses suffer from light deficiency. Artificial light provided by light-emitting diodes (LEDs) is used to increase their growth and adjust their development. Flavonoids like flavonols and anthocyanins are influenced by light conditions and temperature. Increased blue light can elevate the content of these secondary metabolites. Remote measurements of internal parameters using non-destructive methods provided information on their content under different temperature conditions for quality monitoring. This experiment tested flavonoid contents in Kentucky bluegrass (Poa pratensis) for different blue-to-red light ratios (0.6 and 0.4) and three temperature courses (constant temperature of 4 °C, constant temperature of 12 °C, and temperature switching among 12–8–4–8–12 °C). The results show elevated levels of flavonoids under blue-dominant artificial light as well as increased content under low-temperature (4 °C) conditions. The lack of flavonoids at elevated temperatures (12 °C), especially under red-dominant light, suggests an increased requirement for artificial blue light at increased temperatures. Non-destructive flavonoid determination was suitable for this experiment and can therefore be used for practical sports turf quality monitoring. [ABSTRACT FROM AUTHOR]

Optical temperature sensing based on luminescence intensity ratio shows significant potential in achieving accurate temperature detection. In this work, Sb3+/Mn2+ co-doped Cs 2 NaYCl 6 double perovskites were synthesised via a hydrothermal method. Introducing Sb3+ ions to the host significantly enhances the radiative recombination of self-trapped excitons (STEs), resulting in a broad blue emission. The co-doping of Mn2+ ions to the composition leads to a tunable dual-emission in the spectra, originating from the energy transfer between the STEs and Mn2+ ions. The dependence of the dual-emission on temperature is employed for optical temperature sensing. The maximum relative sensitivity, optimal thermal resolution, and optimal thermal repeatability are determined as 1.40 % K−1, 0.002 K and 99.3% at 250 K, respectively. The results indicate that the synthesised Cs 2 NaYCl 6 : Sb3+/Mn2+ double perovskites are promising candidates for high-sensitivity optical thermometers. [ABSTRACT FROM AUTHOR]

Alternating current electroluminescent (ACEL) devices have attracted tremendous attention due to their significant applications in bioinspired electronics, smart wearables, and human-machine interfaces. However, it still faces limitations in real-time visual temperature sensing. Herein, a universal strategy is established to achieve real-time temperature dynamic visualization by integrating a thermochromic layer through a simple spin coating procedure. Such elaborate integration permits the device to display a wide array of luminous colors and achieve high-contrast color transitions in response to ambient temperature variations. More importantly, a quantitative relationship can be established between the temperatures and the luminous color changes. This advancement not only enhances multi-color emission capabilities but also enables the display of diverse information, marking a significant stride in the development of dynamic temperature sensing in ACEL devices.

Electronic textiles (e-textiles) build upon existing technologies to develop truly smart textiles: garments that sense, react, and adapt. Thermoregulatory e-textiles are an area of significant interest across the field. Designing e-textiles that satisfy electrical performance and simple construction is a significant challenge. To address these issues, a simple dip-coating and in-situ polymerization method was used to develop the first example of a thermoregulatory e-textile using green synthesized silver nanoparticles (AgNP) and polypyrrole (Ppy), based on the method previously reported (Naysmith, A.; Mian, N.S.; Rana, S. Development of conductive textile fabric using Plackett–Burman optimized green synthesized silver nanoparticles and in situ polymerized polypyrrole. Green Chemistry Letters and Reviews 2023, 16 (1)). This methodology was optimized using a Taguchi statistical design determining the optimal AgNP-Ppy synthesis method to obtain high performance Joule heating e-textiles, novel within the field of e-textiles. Reactant concentration and reaction time had the largest effects on the electrical resistance of subsequent e-textiles. The result is the first example of an e-textile heater based on green synthesized AgNPs. The e-textile demonstrated exceptional Joule heating (120°C), low electrical resistance (37 Ω), resistive temperature sensing behavior (negative TCR = −0.0046), and increased thermal conductivity (19.55 l (Wm−1 K−1)); the strain sensing behavior (gauge factor = −0.07). This work extends knowledge of the development and challenges within e-textile technologies as the field creates the next generation of textiles.

Enhancing sediment accumulation monitoring techniques in sewers will enable a better understanding of the build-up processes to develop improved cleaning strategies. Thermal sensors provide a solution to sediment depth estimation by passively monitoring temperature fluctuations in the wastewater and sediment beds, which allows evaluation of the heat-transfer processes in sewer pipes. This study analyses the influence of the flow conditions on heat-transfer processes at the water–sediment interface during dry weather flow conditions. For this purpose, an experimental campaign was performed by establishing different flow, temperature patterns, and sediment depth conditions in an annular flume, which ensured steady flow and room-temperature conditions. Numerical simulations were also performed to assess the impact of flow conditions on the relationships between sediment depth and harmonic parameters derived from wastewater and sediment-bed temperature patterns. Results show that heat transfer between water and sediment occurred instantaneously for velocities greater than 0.1 m/s, and that sediment depth estimations using temperature-based systems were barely sensitive to velocities between 0.1 and 0.4 m/s. A depth estimation accuracy of ±7 mm was achieved. This confirms the ability of using temperature sensors to monitor sediment build-up in sewers under dry weather conditions, without the need for flow monitoring. HIGHLIGHTS Combining temperature measurements and analysis of heat-transfer processes can be used to estimate sediment depths in sewers.; Neglecting hydraulic variables barely affected the accuracy of the depth estimations.; Temperature-based systems can be low-cost and easy to scale and implement in sewer systems.; These devices can lead to optimal inspection and cleaning strategies, as well as in other urban drainage systems.;

We present a slope-assisted configuration for fiber-optic temperature sensing using multimodal interference (MMI) in a single-mode-multimode-single-mode structure. By measuring the power in the slope of the MMI spectrum, this method overcomes conventional limitations, enabling high-speed temperature measurement without the need for wavelength sweeping. The operational principles of this technique are described in detail, and a thorough evaluation of its limitations is conducted. [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]

Although upconversion luminescence (UCL) materials have attracted considerable attention in biomedical, lighting, anti-counterfeiting, and solar cells due to their excellent fluorescence properties, reports of the dibarium gadolinium aluminum oxide (Ba 2 GdAlO 5) are scarce. Herein, we synthesized the single-phase Ba 2 GdAlO 5 material with non-stoichiometric Ba 2 Gd 1.06 Al 0.94 O 5 (denoted as BGAO, hereafter). The X-ray Rietveld refinement reveals that the substitution of Gd for Al accounts for the non-stoichiometry. Notably, the UCL properties of BGAO are realized by doping with Yb3+ and Er3+ ion pair, and it can be further enhanced significantly by co-doping with appropriate Zn2+ ions. The SEM images show that the particle size increases as the concentration of Zn2+ ions increases. The X-ray Rietveld refinement results of the Zn-doped BGAO: 0.1 Yb3+, 0.03Er3+ phosphor indicate the substitution of Zn2+ for Ba2+ and Al3+ ions simultaneously. Grain growth and lattice distortion account for the improvement of UCL properties after Zn2+ ions doping. In addition, the temperature sensing performance of the Zn2+-doped sample has been researched based on the fluorescence intensity ratio (FIR) technique, and the maximum absolute and relative sensitivities (S A-max and S R-max) are obtained to be 4.8 × 10−3 K−1 at 498 K and 1.1% K−1 at 298 K, respectively. This work provides a candidate with high UCL intensity for potential applications in optical temperature sensors. [ABSTRACT FROM AUTHOR]

In this study, Silicon Carbide (SiC) nanoparticle-based serigraphic printing inks were formulated to fabricate highly sensitive and wide temperature range printed thermistors. Inter-digitated electrodes (IDEs) were screen printed onto Kapton® substrate using commercially avaiable silver ink. Thermistor inks with different weight ratios of SiC nanoparticles were printed atop the IDE structures to form fully printed thermistors. The thermistors were tested over a wide temperature range form 25 °C to 170 °C, exhibiting excellent repeatability and stability over 15 h of continuous operation. Optimal device performance was achieved with 30 wt.% SiC-polyimide ink. We report highly sensitive devices with a TCR of −0.556%/°C, a thermal coefficient of 502 K (β -index) and an activation energy of 0.08 eV. Further, the thermistor demonstrates an accuracy of ±1.35 °C, which is well within the range offered by commercially available high sensitivity thermistors. SiC thermistors exhibit a small 6.5% drift due to changes in relative humidity between 10 and 90%RH and a 4.2% drift in baseline resistance after 100 cycles of aggressive bend testing at a 40° angle. The use of commercially available low-cost materials, simplicity of design and fabrication techniques coupled with the chemical inertness of the Kapton® substrate and SiC nanoparticles paves the way to use all-printed SiC thermistors towards a wide range of applications where temperature monitoring is vital for optimal system performance. [ABSTRACT FROM AUTHOR]

Polymer-derived SiBCN ceramics with good high-temperature stability and temperature-sensitive properties can be used in real-time temperature monitoring in the aeronautical industry. However, previous investigations mostly focus on the temperature sensitivity of SiBCN ceramics but neglect the fast temperature conversion of the real operating environment and its effect on the temperature sensitivity, which hinders their further practical application. In this study, the response to rapid temperature changes of polymer-derived SiBCN was studied. SiBCN ceramics maintain excellent high-temperature semiconductor performance under rapid heating, and its direct-current (DC) conductivity increases with increasing temperature. The conductive mechanism conforms to the amorphous semiconductor formula, following three different transition mechanisms in different temperature regions. The resistance of SiBCN increases with the number of cycles during 100 cycles of 500–1200 °C, presenting excellent temperature-sensitivity and relatively good sensing stability. This work demonstrates that SiBCN ceramics can maintain excellent temperature-resistance under extreme environments with rapid heating and cooling, and it is hoped that this work could guide the development of temperature sensors for extreme environments in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Glass ceramics (GCs) containing PbS quantum dots (QDs) are prepared for temperature sensing. Broadband emissions are detected in the GCs when PbS QDs are precipitated from the glasses, and emissions centers are modulated from 1250 nm to 1960 nm via heat treatments. The emission centers of GCs exhibit blue-shifts when environment temperatures increase from room temperature to 210 °C. Importantly, the shift values of emission centers increase linearly with the test temperature, which is beneficial for applications in temperature sensing. A temperature sensor based on PbS QDs GC is heat-treated at 500 °C for 10 h, possesses the highest sensitivity of 0.378 nm/°C, and exhibits excellent stability and repeatability at high temperatures (up to 210 °C). Moreover, GC fibers are fabricated by using the GCs as the fiber core. The sensitivity of the temperature-sensing sensor of the GC fibers is also demonstrated and the sensitivity is as high as 0.558 nm/°C. The designed PbS QDs GCs provide a significant materials base for the manufacturing of fluorescent temperature sensors and the GC fibers offer significant opportunities for temperature detection in complex, integrated and compact devices. [ABSTRACT FROM AUTHOR]

In this study, we investigate micrometer-sized NaYF4 crystals double-doped with Yb3+/Er3+ lanthanide ions, designed for temperature-sensing applications. In contrast to previous studies, which focused predominantly on the high-temperature regime, our investigation spans a comprehensive range of both high and ultralow temperatures. We explore the relationship between temperature and the upconversion luminescence (UCL) spectra in both frequency and time domains. Our findings highlight the strong dependence of these spectral characteristics of lanthanide-doped NaYF4 crystals on temperature. Furthermore, we introduce a dual-mode luminescence temperature measurement technique, leveraging the upconversion emission intensity ratio for both green and red emissions. This study also examines the correlation between temperature sensing, energy level disparities, and thermal coupling in Er3+ ions across various temperature scales. Our research contributes to advancing the understanding and application of lanthanide-doped materials, setting a foundation for future innovations in temperature sensing across diverse fields. [ABSTRACT FROM AUTHOR]

A material-modified Fresnel reflection enhancing high-sensitive fiber-tip temperature sensing method is theoretically proposed and experimentally demonstrated. High refractive index semiconductive nano-ZnO and nano-TiO 2 as doping materials enhance the Fresnel reflection in fiber tip probes, and the interference spectrum of these reflected light shows better sensing performance than when undoped. On this basis, the sensitivity is further improved by utilizing ultraviolet (UV) irradiation due to the UV sensibility of the modified materials. By comparing the sensing performance of different material-doping sensing probes, the ZnO-doped fiber tip sensor witnesses the highest temperature sensitivity, which is 94.1 pm/°C. Thanks to the positive role of UV irradiation, this number increases to 141 pm/°C. The proposed fiber tip sensor has a sturdy structure, simple and economical preparative process, competitive sensitivity, high linearity, satisfactory repeatability, and stability. The micron-scale reflective probe enables better detection of extreme environments and can be expected to conduct high-sensitivity temperature sensing in industrial, biomedical, chemical, environmental, and military regions. [ABSTRACT FROM AUTHOR]

Multifunctional sensors have played a crucial role in constructing high-integration electronic networks. Most of the current multifunctional sensors rely on multiple materials to simultaneously detect different physical stimuli. Here, we demonstrate the large piezo-pyroelectric effect in ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals for simultaneous pressure and temperature sensing. The outstanding piezoelectric and pyroelectric properties of PMN-PT result in rapid response speed and high sensitivity, with values of 46 ms and 28.4 nA kPa−1 for pressure sensing, and 1.98 s and 94.66 nC °C−1 for temperature detection, respectively. By leveraging the distinct differences in the response speed of piezoelectric and pyroelectric responses, the piezo-pyroelectric effect of PMN-PT can effectively detect pressure and temperature from mixed-force thermal stimuli, which enables a robotic hand for stimuli classification. With appealing multifunctionality, fast speed, high sensitivity, and compact structure, the proposed self-powered bimodal sensor therefore holds significant potential for high-performance artificial perception. [ABSTRACT FROM AUTHOR]