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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]

BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors were synthesized using the high-temperature solid-state reaction method. The optimal doping concentrations for the three dopant ions Nd3+, Yb3+, and Ho3+ were determined to be 1 mol%, 6 mol%, and 0.8 mol%, respectively, through the method of controlling variables. By analyzing the dependence of the up-conversion luminescence intensity on the pump current of the 980 nm laser, it was found that the green and red up-conversion emissions of Ho3+ ions under 980 nm laser excitation were both two-photon processes. Furthermore, the influence of temperature on the up-conversion luminescent properties of BaGeTeO6: Nd3+/Yb3+/Ho3+ green up-conversion phosphors under 980 nm laser excitation was investigated, and the temperature sensing properties of Ho3+ ions were discussed. The results indicated that, at room temperature and higher temperatures, both the red and green up-conversion emissions of the sample were two-photon processes. Within the range of excitation current used in the experiment, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions was independent of the laser excitation current but correlated with the sample temperature. In the temperature range of 303–723 K, the ratio of red to green up-conversion luminescence intensity of Ho3+ ions exhibited a nonlinear relationship with temperature. Comparing the temperature sensing sensitivity of Ho3+ in different matrices, the results indicated that the sample possessed high temperature sensing sensitivity. [ABSTRACT FROM AUTHOR]

Using a solid-state technique under low temperature conditions, Er3+/Yb3+ co-doped Bi2Mo2O9 phosphors with different concentrations were prepared, exhibiting excellent green up-conversion luminescence property. A thorough investigation was conducted on the phase structure, optical transition, up-conversion luminescence, and down-shifting luminescence properties of the prepared samples. Bi2Mo2O9: Er3+/Yb3+ phosphors excited at 381, 980, and 1550 nm showed strong green fluorescence together with very faint red emission. The mechanism of up-conversion luminescence and its capacity for temperature sensing were examined under the excitation of various wavelengths. Under 980 nm excitation, the maximal relative and absolute sensitivities were determined to be 1.107%K− 1 and 0.756%K− 1 at 303 K and 513 K, respectively. Furthermore, the Judd-Ofelt intensity parameters of Er3+ in Bi2Mo2O9: Er3+/Yb3+ phosphors were calculated using the diffuse reflectance spectra and fluorescence lifetime of Er3+. In addition, material was combined with polyacrylic acid to make an anti-counterfeiting pattern. The results indicate that Bi2Mo2O9: Er3+/Yb3+ phosphor is an excellent green phosphor with optical temperature measurement function, and it also has certain applications in the field of anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Developing highly sensitive optical thermometers is of great significance due to their capability to enable remote and non-contact temperature measurements, rendering them highly applicable in diverse and harsh environments. Herein we report a temperature-dependent phosphor of 0D metal halide hybrid by incorporating Bi3+ into the (MePPh3)2ZnCl4 matrix. Through Bi3+ doping, the initially non-luminescent (MePPh3)2ZnCl4 matrix exhibits a deep-blue emission centered at 453 nm, with a photoluminescence quantum yield (PLQY) of 5.71% and a Stokes shift of 75 nm at room temperature. Experimental characterization demonstrates that exciton-like luminescence of Bi3+ is mainly responsible for the blue emission. Single crystals of Bi3+-doped (MePPh3)2ZnCl4 show an unusual correlation between photoluminescence (PL) lifetime and temperature. Particularly, the dependence of luminescence lifetime on temperature is most remarkable in the temperature range of 80 to 100 K with an exceptional sensitivity up to 0.09 K−1, representing one of the best levels for thermometry based on PL decay lifetime. Our work not only provides a viable strategy for designing a novel, environmentally friendly, and stable blue emitter, but also paves the way for precise thermometric application at low temperature. [ABSTRACT FROM AUTHOR]

The Optical properties of the FBTC (1-((4-((5-chlorobenzo[d]oxazol-2-ylthio)methyl)-1H-1,2,3-triazol-1-yl)methyl)-3H-benzo[f]chromen-3-one) molecule were studied experimentally and theoretically. The spectra of absorption and fluorescence were recorded in various solvents to explore their Solvatochromic behavior and dipole moment at room temperature. To determine the ground and excited state of dipole moment experimentally and theoretically, we employed different Solvatochromic techniques, including microscopic solvent polarity functions developed by Lippert, Bakhshiev, Kawaski-Chamma-Viallet, and Reichardt's, as well as density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The stability of the excited state dipole moment in FBTC is higher. Using prime functional, FBTC was optimized in its ground state, and its HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital), energies were estimated. These values were then compared with those obtained through cyclic voltammetry. Based on the HOMO and LUMO values given, we calculated the global reactivity parameter and energy gap, which was found to be low at 3.77 eV. This study also includes an estimation of electron absorption energies and oscillator strength. Natural population analysis (NPA), Milliken atomic charge, and molecular electrostatic potential (MESP) map are correlated. In addition, FBTC exhibited exceptional physiological temperature sensing behaviour from 20 °C -65 °C with high relative sensitivity and firm stability. Hence these results confirm that FBTC is a potential candidate for photonic devices and it's also applicable in optical temperature sensing. [ABSTRACT FROM AUTHOR]

Transdermal drug delivery has emerged as an alternative to conventional drug delivery systems as it enables painless and convenient drug administration. However, next-generation healthcare systems need to facilitate "on-demand" delivery operations and should be highly efficient to penetrate the physiological barriers in the skin. Here, we report an ultrathin dye-loaded epidermal tattoo (UDET) that allows wirelessly stimulated drug delivery with high efficiency. The UDET consists of an electrospun dye-loaded silk nanofiber mat and a covered carbon nanotube (CNT) layer. UDETs are conformally tattooed on pigskins and show stable operation under mechanical deformation. Biological fluorescence dyes such as vitamin B12, riboflavin, rhodamine B, and sodium fluorescein are applied as model drugs. Illuminating the UDET by a low-power light-emitting diode (< 34.5 mW/cm2) triggers transdermal drug delivery due to heat generation. The CNTs convert the absorbed light into heat, and then the dyes loaded on silk can be diffused through the epidermis. The CNT layer is electrically conductive and can detect the temperature by reading the resistance change (0.1917 Ω/°C). This indicates that the UDET can be used simultaneously to read temperature and deliver the loaded dye molecules, making it a promising on-demand drug delivery strategy for future medicine technology. [ABSTRACT FROM AUTHOR]

This paper presents a dual-core two-parameter optical fiber sensor based on the surface plasmonic resonance (SPR) effect. It is analyzed by the finite element method. The proposed sensor is a dual-channel structure designed with photonic crystal fiber (PCF) as the base material: one channel is coated with a gold film to measure the refractive index (RI) of the solution to be measured, and the other channel is coated with a gold film and polydimethylsiloxane to measure the temperature of the solution to be measured. The exposed microslot structure on both sides reduces the complexity of sensing measurements. The results show that the maximum RI sensitivity of the sensor is 19,900 nm/RIU, and the maximum sensitivity to temperature is 8.7 nm/℃. This work is conducive to realizing a PCF sensor with high sensitivity, large measurement range, real-time monitoring, and easy preparation. As a result, the sensor is expected to be widely used in fields such as biology and chemicals. [ABSTRACT FROM AUTHOR]

A series of BiTa7O19(BTO):Ho3+/Yb3+ phosphors were prepared by high-temperature solid state sintering, which exhibited outstanding pure green upconversion luminescence (UCL) under 980 nm laser excitation. When Ho3+ doping 10 mol%, Yb3+ has almost no concentration quenching point. By optimizing the preparation process, the phase purity of the sample can be improved. Under 980 nm laser excitation power density of 124.99 W/cm2, the UCL intensity of the optimized sample is 1.79 times that of the non-optimized sample. The maximum relative temperature sensitivity SR of 0.384% K−1 at 557 K and 0.40% K−1 at 723 K can be obtained by using luminescence intensity ratio (LIR) technique. All experiments show that BTO is an excellent UCL host, and BTO:Ho3+/Yb3+ can be used in UCL display and temperature sensing. [ABSTRACT FROM AUTHOR]

High efficiency Li0.5La0.5SrMgWO6:Mn4+,Eu3+ phosphor was synthesized via the solid-state reaction technique. The XRD, excitation, emission spectra, as well as temperature sensing properties were quantitatively measured. Upon excitation by a 395-nm LED source, the emission peaks were observed at 615 nm and 693 ∼ 707 nm. The quantum efficiency was obtained to be 69%, and the slope efficiency was determined to be 21%. We have also observed that the fluorescence intensity can be modulated through two means, namely, the concentration ratio of Eu3+:Mn4+ and the substitution position of Eu3+. The highest intensity ratio between 615 nm and 693 nm occurs when Eu3+: Mn4+ = 20:1. And the sample "0.5Sr 0.5Mg" exhibits the highest intensity ratio between 615 nm and 693 nm. The fluorescence mechanism has been discussed in light of the theory of energy level transitions, which suggests that the phenomenon of cross relaxation ensures high efficiency. Finally, we investigated the temperature sensing properties of "0.1%Mn 1%Eu" and "0.1%Mn 2%Eu" samples, revealing that the samples exhibit a temperature sensing range of 0.2% ∼ 1.3% /K for Eu: Mn = 10 and 0.1% ∼ 0.4% /K for Eu: Mn = 20, indicating the former's superior suitability as a temperature-sensitive material. The material can be utilized not only for plant cultivation but also as a temperature sensor to monitor the environmental temperature during plant growth. In comparison with traditional Mn4+ doping materials, it is more suitable for plant cultivation, particularly in greenhouse facilities. [ABSTRACT FROM AUTHOR]

High efficiency Li0.5La0.5SrMgWO6:Mn4+,Eu3+ phosphor was synthesized via the solid-state reaction technique. The XRD, excitation, emission spectra, as well as temperature sensing properties were quantitatively measured. Upon excitation by a 395-nm LED source, the emission peaks were observed at 615 nm and 693 ∼ 707 nm. The quantum efficiency was obtained to be 69%, and the slope efficiency was determined to be 21%. We have also observed that the fluorescence intensity can be modulated through two means, namely, the concentration ratio of Eu3+:Mn4+ and the substitution position of Eu3+. The highest intensity ratio between 615 nm and 693 nm occurs when Eu3+: Mn4+ = 20:1. And the sample "0.5Sr 0.5Mg" exhibits the highest intensity ratio between 615 nm and 693 nm. The fluorescence mechanism has been discussed in light of the theory of energy level transitions, which suggests that the phenomenon of cross relaxation ensures high efficiency. Finally, we investigated the temperature sensing properties of "0.1%Mn 1%Eu" and "0.1%Mn 2%Eu" samples, revealing that the samples exhibit a temperature sensing range of 0.2% ∼ 1.3% /K for Eu: Mn = 10 and 0.1% ∼ 0.4% /K for Eu: Mn = 20, indicating the former's superior suitability as a temperature-sensitive material. The material can be utilized not only for plant cultivation but also as a temperature sensor to monitor the environmental temperature during plant growth. In comparison with traditional Mn4+ doping materials, it is more suitable for plant cultivation, particularly in greenhouse facilities. [ABSTRACT FROM AUTHOR]

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In this work, a plasmonic sensor based on metal–insulator–metal (MIM) waveguide for temperature sensing application is numerically investigated via finite element method (FEM). The resonant cavity filled with PDMS polymer is side-coupled to the MIM bus waveguide. The sensitivity of the proposed device is ~ − 0.44 nm/°C which can be further enhanced to − 0.63 nm/°C by embedding a period array of metallic nanoblocks in the center of the cavity. We comprehend the existence of numerous highly attractive and sensitive plasmonic sensor designs, yet a notable gap exists in the exploration of light coupling mechanisms to these nanoscale waveguides. Consequently, we introduced an attractive approach: orthogonal mode couplers designed for plasmonic chips, which leverage MIM waveguide-based sensors. The optimized transmission of the hybrid system including silicon couplers and MIM waveguide is in the range of − 1.73 dB to − 2.93 dB for a broad wavelength range of 1450–1650 nm. The skillful integration of these couplers not only distinguishes our plasmonic sensor but also positions it as a highly promising solution for an extensive array of sensing applications. [ABSTRACT FROM AUTHOR]

Mortar beams incorporating carbon nanofibers (CNFs), which were synthesized in situ on Portland cement particles, were used to produce nanomodified Portland cement sensors (SmartCem sensors). SmartCem sensors exhibited an electrical response comparable to a thermistor with a temperature coefficient of resistivity of − 0.0152/ °C. The highest temperature sensing was obtained for the SmartCem sensor, which contained ~ 0.271 wt.% of CNFs. The calculated temperature sensitivity was approximately 11.76% higher in comparison with the mortar beam containing only unmodified Portland cement. SmartCem sensors were used to monitor the cement hydration in large-scale self-compacting concrete beams. The measurements were conducted after casting for 7 days. Additionally, commercially available thermocouple and humidity sensors were used as references. The results showed that changes in electrical resistivity measured by the SmartCem sensor were well aligned with the ongoing hydration processes. [ABSTRACT FROM AUTHOR]

Rare earth ion-doped upconversion luminescent materials have found extensive utility in anti-counterfeiting applications. However, in practice, single-mode photoluminescence falls short of addressing increasingly intricate demands of contemporary anti-counterfeiting measures. This work presents successfully synthesized dual-mode excited SrBi4Ti4O15 upconversion phosphor doped with Yb3+/Er3+, designed to emit two distinctive colors, green and red under excitation at either 980 or 1550 nm. Introduction of the multi-color emission significantly enhances the security of anti-counterfeiting strategies in a variety of modes. A comprehensive investigation is conducted into potential upconversion mechanisms driven by different excitation sources, examining both 980 and 1550 nm wavelengths. Anti-counterfeiting properties are evaluated for synthesized phosphor by gauging the luminous intensity ratio between red and green light. Research findings unequivocally point to the immense potential of SrBi4Ti4O15 upconversion phosphor doped with Yb3+/Er3+ for robust multimode anti-counterfeiting applications, representing a promising development in this field. [ABSTRACT FROM AUTHOR]

In this paper, a metal–insulator–metal waveguide is paired with a hexagonal irregular ring resonator to construct a high sensitivity refractive index plasmonic nano-sensor in this work. The sensing properties of the proposed design are studied using a numerical solution in the finite-difference time-domain. The acquired results reveal a linear connection between the material's refractive index (RI) and the wavelength of resonances. Furthermore, the maximum linear sensitivity for the second mode is S = 2417 nm/RIU, with a figure of merit (FOM) of 38, whereas the highest for the first mode is S = 1002 nm/RIU, with a FOM of 28.6. With a sensitivity of 1.02 nm/°C, this sensor is also being examined as a temperature sensor. When ethanol is employed as the measuring liquid, the sensor's operating temperature range is between—114.3 and 78 °C. This device can create a path toward RI by being highly sensitive for the label-free diagnosis of different molecules and providing temperature sensing abilities. It can also be used in microchip processors and has a wide spectrum of biological applications. [ABSTRACT FROM AUTHOR]

Increasing demand for fire safety has aroused the enthusiasm of researchers for exploring early-stage fire-warning materials. Herein, an early-stage fire-warning cotton fabric (denoted as CF-CP-FR) was designed with a two-layered structure: conducting polymer layer and flame-retardant layer, through in-situ chemical oxidation polymerization of polypyrrole (PPy) and dip coating of the compound of montmorillonite and ammonium polyphosphate (MMT@APP), respectively. Based on the thermoelectric effect of the PPy, CF-CP-FR was endowed with accurate temperature sensing capability below 100 °C. When encountering fire, CF-CP-FR showed excellent fire-warning response as fast as 1.0 s and displayed repeatable fire-warning capability under the protection of the MMT@APP. Via the mechanism of thermo-induced resistance change, the coated cotton fabric could also trigger the fire warning circuit at ca. 2.0 s. Meanwhile, the flame retardancy and thermal stability of CF-CP-FR were significantly enhanced, owing to the synergetic effect of MMT and APP. This work is promising in fabricating multifunctional clothing with efficient fire safety and smart fire-warning capability. [ABSTRACT FROM AUTHOR]

As one of the promising human—machine interfaces, wearable sensors play an important role in modern society, which advances the development of wearable fields, especially in the promising applications of electronic skin (e-skin), robotics, prosthetics, and healthcare. In the last decades, wearable sensors tend to be capable of attractive capabilities such as miniaturization, multifunction, and smart integration, and wearable properties such as lightweight, flexibility, stretchability, and conformability for wider applications. In this work, we developed a stretchable multifunctional sensor based on porous silver nanowire/silicone rubber conductive film (P-AgNW/SR). Its unique structural configuration, i.e., an assembly of the P-AgNW/SR with good conductivity, stability, and resistance response, and the insulated silicone rubber layer, provided the feasibility for realizing multiple sensing capabilities. Specifically, porous microstructures of the P-AgNW/SR made the device to be used for pressure sensing, exhibiting outstanding dynamic and static resistive responsive behaviors and having a maximum sensitivity of 9.062 %·N−1 in a continuous compressive force range of ∼ 16 N. With the merit of the good piezoresistive property of AgNW/SR networks embedded into the surface of micropores of the P-AgNW/SR, the device was verified to be a temperature sensor for detecting temperature changes in the human body and environment. The temperature sensor had good sensitivity of 0.844 %·°C−1, high linearity of 0.999 in the range of 25–125 °C, and remarkable dynamic stability. Besides, the developed sensor was demonstrated to be a single electrode-triboelectric sensor for active sensing, owing to the unique assembly of the conductive P-AgNW/SR electrode and the silicone rubber friction layer. Based on the coupling effect of the triboelectrification and electrostatic induction, the generated electrical signals could be used to sense the human motions, according to the quantitative correlation between the human motions and the features in amplitude and waveform of the output signals. Thus, the developed stretchable sensor successfully achieved the integration of two types of passive sensing capabilities, i.e., pressure and temperature sensing, and one type of active sensing capability, i.e., triboelectric sensing, demonstrating the feasibility of monitoring multiple variables of the human body and environment. [ABSTRACT FROM AUTHOR]

In this study, the temperature sensing behaviors of emissions of Stark sublevels in Er3+/Yb3+ codoped lead lanthanum zirconate titanate (PLZT) transparent ceramic were examined. Based on the temperature-dependent upconversion fluorescence spectra excited by 980 nm, the emission intensities of the Stark sublevels 2H11/2(1, 2), 4S3/2(1, 2), and 4F9/2(1, 2, 3) were obtained upon increasing the temperature from 160 to 320 K. All the transitions present strong temperature dependence under the competitive effects of thermal excitation and nonradiative relaxation. The optical temperature sensing properties of 2H11/2/4S3/2(1), 2H11/2/4S3/2(2), 2H11/2/4F9/2(1), 2H11/2/4F9/2(2), and 2H11/2/4F9/2(3) were investigated using the fluorescence intensity ratio (FIR) technique. The largest absolute sensitivity Sa of 142.4 × 10–4 K−1 was obtained based on the FIRs of 2H11/2/4F9/2(1) at 320 K, which is approximately 26 times larger than that of traditionally used thermal coupled levels 2H11/2/4S3/2 in the considered sample. In contrast, the maximum relative sensitivity Sr was 2.21% K−1 at 203 K. A comparison of these results with those of other Er3+/Yb3+ codoped materials reveals that Er3+/Yb3+: PLZT ceramics are a promising thermometer material at low temperatures. Applying FIRs based on the photoluminescence of Stark sublevels is a practical approach to achieving greater thermometric efficiency. [ABSTRACT FROM AUTHOR]

A novel design for a plasmonic sensor, consisting of a metal–insulator–metal waveguide with a coupled circle-semi-ring resonator is proposed and investigated in this paper. We carried out the theoretical analysis for the wave-guiding characteristics by utilizing the two-dimensional (2D) finite-difference time-domain method. The effects of the electromagnetic wave transmission, field profile distribution, temperature and refractive index (RI) sensing characteristics on the structural parameters were studied in detail. The simulation results indicate that proposed sensor possesses a RI sensitivity up to 990 nm/refractive index unit and a temperature sensitivity of − 0.42 nm/°C with optimized geometric parameters. The compact waveguide structure may be widely utilized in areas of sensing and integrated circuits. [ABSTRACT FROM AUTHOR]

In this work, by using a flexible tricarboxylate ligand 5-(4-carboxybenzyloxy) isophthalic acid (H3L), a novel pillar-layered Mn–organic framework, namely, [(CH3CH2)2NH2][Mn3(HL)L(AC)2] (SQNU-23, SQNU = Shangqiu Normal University), was synthesized by using a DEF/HAc solvent system. In SQNU-23, each S-shaped Mn-O chain is interconnected by two bridging modes of organic ligand to form a 3D pillar-layered framework with 1D rectangular channels. The solid-state fluorescence of SQNU-23 exhibits a significant red shift of about 140 nm compared to that of organic ligand. Moreover, SQNU-23 as a luminescent thermometer exhibits good linear dependence in the wide temperature range (100 to 300 K). [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) is an ideal substitute for traditional fluorescent temperature sensing materials due to its excellent luminescence properties. However, the poor linear correlation between the fluorescence intensity and temperature leads to low-temperature sensing sensitivity. This study aims to prepare CQDs with a high linear correlation between fluorescence intensity and temperature from Loblolly pine wood processing waste by the one-pot hydrothermal method. The synthesized CQDs presents temperature-dependent blue fluorescence. At 0–60°C, the fluorescence intensity of CQDs has a good linear relationship with temperature, and a wide response range. Under this temperature response range, the fluorescence intensity series data of the CQDs obtained experimentally, and the chemical reaction rate series data calculated by the Arrhenius equation have a high degree of fit, high sensitivity. Reversible the fluorescence recovery rate is high. Under cryogenic storage conditions, the PL emission retention rate of CQDs after 60 d storage is high. [ABSTRACT FROM AUTHOR]

Optical thermometry based on luminescence intensity ratio (LIR) is a hot topic in temperature sensing, due to fast response, high precision, the benefit of non-contact, etc. In this paper, the temperature-sensing capability of GdPO4:1%Dy3+ phosphor was investigated through the approach of fluorescence intensity ratio based on the thermally coupled energy levels of Dy3+. The results show that the intensity of the emission, recorded under a 355 nm laser excitation, markedly increases with increasing temperature from 290 to 539 K. The LIR between the intensities of the emission of thermally coupled energy levels corresponding to 4I15/2 → 6H15/2 and 4F9/2 → 6H15/2 transitions monotonously increased with increasing temperature within the investigated temperature range. The maximum value of the relative sensitivity reaches the value of 1.55% K−1 at 290 K, which is higher than the values reported in previous studies for similar phosphors. This finding suggests that the produced Dy3+-doped GdPO4 phosphor is a promising candidate material for application in optical temperature sensing. Furthermore, the high relative sensitivity of 1.34% K−1 was attained in the physiological temperature of the human body (310 K), which qualifies the produced phosphor for biological applications. [ABSTRACT FROM AUTHOR]

Developing a cotton fabric sensing layer with good waterproofness and breathability via a low-cost and eco-friendly method is increasingly important for the construction of comfortable and wearable electronic devices. Herein, a waterproof and breathable cotton fabric composite decorated by reduced graphene oxide (rGO) and carbon nanotube (CNT), Cotton/rGO/CNT, is reported by a facile solution infiltration method, and we adopt such Cotton/rGO/CNT composite to develop a layer-by-layer structured multifunctional flexible sensor, enabling the high-sensitivity detection of pressure and temperature stimulus. Particularly, the multifunctional flexible sensor exhibits a high response toward tiny pressure, demonstrating salient superiority in the continuous and reliable monitoring of human physiological information. Concerning temperature sensing, a good linear response for the temperatures ranging from 28 to 40 °C is achieved by the multifunctional flexible sensor and gives rise to be successfully applied to the non-contact real-time monitoring of human respiration signal. Finally, an array consisting of multifunctional flexible sensors further demonstrates its feasibility in perceiving and mapping the pressure and temperature information of contact objects. This work provides a feasible strategy for designing cotton-based sensing layers that can effectively resist liquid water penetration and allow water vapor transmission, and offers reasonable insight for constructing comfort and multifunctional wearable electronics. [ABSTRACT FROM AUTHOR]

The reported article covers the down-conversion (DC) and up-conversion (UC) photoluminescence properties of BaWO4 (BWO): Er3+ phosphors, prepared via solid-state reaction route. The prepared samples were subjected to various characterization tools and spectroscopic techniques such as XRD, FESEM, EDX, XPS, PL, FTIR and UV–Vis-NIR for structural and optical characterizations. Intense green emission was achieved from both down-conversion and up-conversion emission spectra under UV excitation of 378 nm and near-infrared excitation of 980 nm, respectively. Green LED is fabricated using a 365 nm UV chip to ensure the performance of the material. The luminescence quenching was observed above 0.5 mol% doping of Er3+, governed by dipole–quadrupole interaction. Decay curves of all samples follow single exponential behavior and the average decay time reduces with the increase of Er3+ concentration. Temperature-dependent UC emission spectra were recorded within 300–500 K. The emission intensity was maintained at 82% at 147 °C compared to the intensity at room temperature, suggesting the good thermal stability of the BWO: Er3+ phosphors. The change in the fluorescence intensity ratio (FIR) between two thermally coupled energy levels of Er3+ ion with temperature has been utilized to investigate the temperature-sensing properties of the reported phosphors. The maximum relative temperature sensitivity was found to be 9.97 × 10–3 K−1 at 300 K. Obtained efficient green emission and comparatively good sensitivity make the proposed phosphor material a promising candidate for the color mixing component of phosphor-converted WLED and temperature-sensing applications. [ABSTRACT FROM AUTHOR]

A micro-groove photonic crystal fiber sensor based on surface plasmon resonance (SPR) is proposed to simultaneously detect the refractive index and temperature of liquid. The sensor structure has three air holes and a micro-groove. The gold film was deposited on the micro-groove for refractive index measurement. The gold film was deposited in the air hole on the right side and filled with polydimethylsiloxane (PDMS) for temperature measurement. The finite element method is used to analyze the sensor characteristics. The numerical results show that the two channels of measuring refractive index and temperature do not interfere, reducing the complexity of two-parameter sensor measurement. When the refractive index of the liquid is in the range of 1.34–1.42 and the temperature is in the range of 0–100 ℃, the maximum spectral sensitivity of the sensor is 14300 nm/RIU and 6.4 nm/℃, respectively. The results also show that the sensor's performance is not sensitive to the change of structural parameters. Therefore, the sensor is easy to manufacture. This high-sensitivity sensor based on micro-groove photonic crystal fiber and surface plasmon resonance has excellent potential in biochemical detection, environmental monitoring, and medical sensing. [ABSTRACT FROM AUTHOR]

In this work, we use the cubic-nonlinear optoelectronic oscillator (CNOEO) in three different configurations to successfully perform the sensings of temperature, refractive index, and distance measurement with high precision. From our results, the use of the CNOEO through the variation of the values of the cubic-nonlinear parameter increases the sensitivity of the different sensings and the measurement carried out compared to the results obtained with the standard OEO which is a particular CNOEO featuring a cubic-nonlinear parameter equal to zero. [ABSTRACT FROM AUTHOR]

Flexible and wearable sensors have broad application prospects in health monitoring and artificial intelligence. Many different single-functional sensing devices have been developed in recent years, such as pressure sensors and temperature sensors. However, it is still a great challenge to design and fabricate tactile sensors with multiple sensing functions. Herein, we propose a simple direct stamping method for the fabrication of multifunctional tactile sensors. It can detect pressure and temperature stimuli signals simultaneously. This pressure/temperature sensor possesses high sensitivity (0.67 kPa−1), large linear range (0.75–5 kPa), and fast response speed (15.6 ms) in pressure sensing. It also has a high temperature sensitivity (1.41%/°C) and great linearity (0.99) for temperature sensing in the range of −30 to 30 °C. All these excellent performances indicate that this pressure/temperature sensor has great potential in applications for artificial intelligence and health monitoring. [ABSTRACT FROM AUTHOR]

We design high-sensitive fiber-optic sensor based on modal interference for temperature measurements. The core mismatch-offset sensor is fabricated by splicing a section of multimode fiber (MMF) between two single-mode fiber (SMF) and offset splicing of SMF. We use the finite-difference beam propagation method to numerically analyze the mode and intensity distributions of the light field in the sensor. We optimize the structure parameters such as the length of MMF, the length of sensing SMF, and the offset of sensor; the optimum parameters of proposed sensor are 4.0 mm, 1.73 cm, and 3.5 μm, respectively. Experimental results show that the proposed sensor is successfully used to monitor the variation of ambient temperature, and it possesses a high temperature sensitivity of 167.2 pm/°C with good linearity. The core mismatch-offset sensor with high sensitivity and compact structure provides a new method for designing fiber-optic sensor and temperature sensing. [ABSTRACT FROM AUTHOR]

Flexible rubber based CNT/CNT-OD/Al cells were designed, fabricated and tested for multi-sensing and filter applications. Rubbing-in technology was used to fabricate the cells containing 12–17 μm thick active layers of CNT-OD (50:50 wt%). I–V characteristics of the cells were measured and the nonlinearity coefficient (β) was found in the interval of 1.8 to 2.3. The cells were tested for pressure, displacement and temperature sensing in the range of 0–33 gf/cm2, 0–250 μm and 21–67 °C, respectively. Sensing mechanism was based on resistance/impedance change. The cells showed sensitivities up to −424.2 Ωcm2/gf, −40.0 Ω/μm and −402 Ω/°C for pressure, displacement and temperature, respectively. The cells' cutoff frequency was equal to 20 kHz. The fabricated cells potentially can be used as displacement, pressure, temperature sensors and frequency low pass filter as well. [ABSTRACT FROM AUTHOR]

Upconversion (UC) phosphors of β-BiNbO4:Er3+/Yb3+ as temperature sensing materials were synthesized using the solid-state method. The structure was characterized by x-ray diffraction (XRD), revealing that all samples exhibited a single triclinic phase. Upon 980 nm laser excitation, the phosphors exhibited strong green emission and relatively weak red emission. Its possible luminescence mechanism is discussed based on the dependence of the UC emission spectra on the pump laser power. Finally, its temperature sensing properties were investigated using the temperature-dependent fluorescence intensity ratio (FIR) of two green emission bands originating from Er3+ ions. The thermal effect from laser irradiation and its influence on temperature sensing were also studied. Its absolute sensitivity SA exhibited a smaller change above 300 K, and reached a maximum value of 5.5‰ K−1 around 400 K. These results indicate that this type of qualified UC phosphor shows potential application in optical temperature sensors, especially at high temperature. [ABSTRACT FROM AUTHOR]

To prepare an electrically conductive clay-composite, in this work, the surface of kaolinite plates was covered with the hydrophobic polythiophene (PTh) nanoparticles, through in-situ oxidative polymerization of thiophene in an organic solvent mixture. By changing the polymerization conditions such as types of solvents used as polymerization media, volume ratios of the solvents in the mixture, and mole ratios of the oxidant/monomer, the composite with the highest conductivity (7.95 × 10–5 S cm−1) was obtained. Depending on the polythiophene (PTh) content (%) of the composite, Vickers microhardness, elastic modulus, Brunauer, Emmett, and Teller (BET) analysis, wet particle size distribution, and water contact angle measurements were performed. It was observed that the hydrophilic nature of kaolinite remarkably altered after the incorporation of PTh particles. FTIR, XRD, TGA, and SEM–EDX techniques were also used for the characterization of the composite. The performance of the composite in the environmental-based sensors, including humidity and temperature sensing, were examined, and the resistance values of the composite exhibited quite stable and reproducible responses, especially to the temperature changes, between 1 and 120 °C compared to the pure PTh. [ABSTRACT FROM AUTHOR]

Prokaryotic cold shock proteins (CSPs) are considered to play an important role in the transcriptional and translational regulation of gene expression, possibly by acting as transcription anti-terminators and "RNA chaperones". They bind with high affinity to single-stranded nucleic acids. Here we report the binding epitope of TmCsp from Thermotoga maritima for both single-stranded DNA and RNA, using heteronuclear 2D NMR spectroscopy. At "physiological" growth temperatures of TmCsp (≥ 343 K), all oligonucleotides studied have dissociation constants between 1.6 ((dT)7) and 25.2 ((dA)7) μM as determined by tryptophan fluorescence quenching. Reduction of the temperature to 303 K leads to a pronounced increase of affinity for thymidylate (dT)7 and uridylate (rU)7 heptamers with dissociation constants of 4.0 and 10.8 nM, respectively, whereas the weak binding of TmCsp to cytidylate, adenylate, and guanylate heptamers (dC)7, (dA)7, and (dT)7 is almost unaffected by temperature. The change of affinities of TmCsp for (dT)7 and (rU)7 by approximately 3 orders of magnitude shows that it represents a cold chock sensor that switches on the cold shock reaction of the cell. A temperature dependent conformational switch of the protein is required for this action. The binding epitope on TmCsp for the ssDNA and RNA heptamers is very similar and comprises β-strands 1 and 2, the loop β1–β2 as well as the loops connecting β3 with β4 and β4 with β5. Besides the loop regions, surprisingly, mainly the RNA-binding motif RNP1 is involved in ssDNA and RNA binding, while only two amino acids, H28 and W29, of the postulated RNA-binding motif RNP2 interact with the uridylate and thymidylate homonucleotides, although a high affinity in the nanomolar range is achieved. This is in contrast to the binding properties of other CSPs or cold shock domains, where RNP1 as well as RNP2 are involved in binding. TmCsp takes up a unique position since it is the only one which possesses a tryptophan residue instead of a usually highly conserved phenylalanine or tyrosine residue at the end of RNP2. NMR titrations suggest that neither (dT)7 nor (rU)7 represent the full binding motif and that non-optimal intercalation of W29 into these oligonucleotides blocks the access of the RNP2 site to the DNA or RNA. NMR-experiments with (dA)7 suggest an interaction of W29 with the adenine ring. Full binding seems to require at least one single purine base well-positioned within a thymine- or uracil-rich stretch of nucleic acids. [ABSTRACT FROM AUTHOR]

We present a new technique designed for in situ measurement of pressure and temperature in lubricating films. An innovative methodology has been developed, based on the photoluminescence properties of non-intrusive CdSe-based nanosize sensors (quantum dots). The sensitivity to pressure and temperature of these sensors dispersed in a carrier fluid was established through calibrations performed in diamond anvil cells. Elastohydrodynamic (EHD) contacts of different combinations of contacting solids (glass-steel, glass-Si3N4, sapphire-steel and sapphire-Si3N4) and submitted to various operating conditions were studied through in situ experiments and numerical simulations. Isothermal experiments were performed first: both experimental central pressures and pressure profiles were obtained, with a very good agreement with the values predicted by the numerical model. A series of non-isothermal experiments were then carried out to perform temperature measurements. Temperature rises in the central zone of EHD contacts involving various material pairs were measured and compared to predictions, leading to a very satisfying agreement. Overall, the deviation between measurements and predictions remained smaller than the uncertainty of the measurement method. Therefore, these findings proved the potential of the methodology to probe in situ pressure and temperature in EHD contacts. Comparative performance with competing techniques was examined in terms of intrusiveness, level of reliability, spatial resolution, accuracy and complexity. As this work is a pioneering development, the technique may be improved in the near future, opening an avenue for even more accurate or faster measurements for example, and eventually offering a better understanding of the mechanisms at work in this type of lubricated interface. [ABSTRACT FROM AUTHOR]

In this work, the upconversion temperature sensing was used to study the light-emitting properties of Gd2(MoO4)3:Y3+/Yb3+/Er3+-based LED. In order to obtain high-intensity upconversion luminescence, we studied the effect of Y3+ doping concentration on the photon upconversion of Yb3+/Er3+-activated Gd2(MoO4)3 under 940 nm excitation. We also explored the calibration of upconversion temperature sensing and established a reliable temperature scale. Finally, the light-emitting properties of an operating LED that consisted of a 940-nm semiconductor chip and the optimum phosphor were studied by using the upconversion luminescence thermometry. [ABSTRACT FROM AUTHOR]

A novel fiber inline Mach-Zehnder interferometer (MZI) is proposed for simultaneous measurement of curvature and temperature. The sensor composes of single mode-multimode-dispersion compensation-multimode-single mode fiber (MMF-DCF-MMF) structure, using the direct fusion technology. The experimental results show curvature sensitivities of −12.82 nm/m−1 and −14.42 nm/m−1 in the range of 0–0.65 m−1 for two resonant dips, as well as temperature sensitivities of 57.6 pm/°C and 74.3 pm/°C within the range of 20 °C–150 °C. In addition, the sensor has unique advantages of easy fabrication, low cost, high fringe visibility of 24dB, and high sensitivity, which shows a good application prospect in dual-parameters of sensing of curvature and temperature. [ABSTRACT FROM AUTHOR]

CuCdO2 delafossite oxide film as an interface layer was coated by sol–gel spin coating on p-Si substrate, and thus an Al/p-Si/CuCdO2/Al diode was fabricated. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) was used to obtain an image of the CuCdO2 oxide film. The temperature-dependent behavior of the diode was studied by current–voltage (I–V) and capacitance/conductance–voltage (C/G–V) measurements over the 100–400 K temperature range. It is observed that the ideality factor (n) decreases and zero-bias barrier height (Φb0) increases with an increase in temperature. This abnormal behavior of n and Φb0 is attributed to barrier inhomogeneities by assuming Gaussian distribution (GD) at the metal–semiconductor interface. For each temperature, the barrier height values obtained from both the conventional I–V and Norde method show good agreement with each other. The I–V–T characteristics have shown the GD, giving a mean barrier height ( Φ ¯ b 0 ) of 1.04 eV and a standard deviation (σs) of 0.12 V. A modified Richardson plot of [ln(I0/T2) − q2σs2/2k2T2 versus q/kT] yields Φ ¯ b 0 and A* as 1.06 eV and 31.21 A cm−2 K−2 (indicating an agreement with the theoretical value of 32 A cm−2 K−2), showing the promise of CuCdO2/Si as temperature sensing with a Schottky junction. In addition, C–V and G–V measurements show that the C value decreases and the G value increases as the frequency increases, depending on a continuous distribution of interface states. Also, the capacitance and the conductance values decrease with increasing temperature. The results suggest that Al/p-Si/CuCdO2/Al diode can be used for temperature sensing applications. [ABSTRACT FROM AUTHOR]

In recent years, upconversion (UC) luminescence has attracted considerable attention because of its potential application in temperature measurement. In this work, LaNbO4:Er3+/Yb3+ phosphors are synthesized using a solid-state method. The x-ray diffraction patterns show that the phosphors obtained exhibit a single monoclinic structure, and doping does not change the crystal structure. Intense green and red emissions are observed upon 980-nm excitation. The emission intensity varies with the doping concentration, and the best doping concentrations are 1 mol.% and 10 mol.% for Er3+ and Yb3+ ions, respectively. The possible luminescence mechanism is investigated based on the UC emission dependence on pump power. The temperature-sensing ability is also investigated based on the fluorescence intensity ratio between two thermally coupled levels 2H11/2 and 4S3/2. The maximum sensitivity achieved is 0.81% K−1 at around 430 K, suggesting that the phosphor is a potential candidate for temperature sensing applications. [ABSTRACT FROM AUTHOR]

Aiming at the achievement of temperature measurement with high sensitivity in the sub-wavelength scale, an all-metal meta-surface (AMMS)-based sensor is numerically demonstrated. Based on the sharp plasmonic resonances and the simultaneous use of perfect absorption response, temperature sensing with an ultra-high enhancement factor of 263 for the spectral figure of merit (FOM) factor is obtained in comparison with that of the common plasmonic sensors. Moreover, spectral shift-related sensitivity S is up to 0.274 nm/°C. These sensing properties indicate the designed sensor can play a significant role in optoelectronic devices for high-integrated and high signal-to-noise ratio temperature detection. [ABSTRACT FROM AUTHOR]

Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNaV) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that “local” domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities. [ABSTRACT FROM AUTHOR]

Quality control requirements imposed on assays used in clinical diagnostics and point-of-care-diagnostic testing (POCT), utilizing amplification reactions performed at elevated temperatures of 35 to 95 °C are very stringent. As the temperature of a reaction vessel has a large impact on the specificity and sensitivity of the amplification reaction, simple tools for local in situ temperature sensing and monitoring are required for reaction and assay control. We describe here a platform of stem-and-loop structured DNA hairpins (molecular beacons, MBs), absorbing and emitting in the visible and red spectral region, rationally designed for precise temperature measurements in microfluidic assays for POCT, and their application for temperature measurements in a common DNA-based molecular biological assay utilizing thermophilic helicase-dependent amplification (tHDA). Spectroscopic studies of these MBs, rationally designed from DNA sequences of different thermal stabilities, chosen not to interact with the DNA probes applied in the nucleic acid amplification assay, and temperature-dependent fluorescence measurements of MB-assay mixtures revealed the suitability of these MBs for temperature measurements directly in such an assay with a temperature resolution of about 0.5 °C without interferences from assay components. Combining two spectrally distinguishable MBs provides a broader response range and an increase in temperature sensitivity up to 0.1 °C. This approach will find future application for temperature monitoring and quality control in commercialized diagnostics assays using dried reagents and microfluidic chips as well as assays read out with tube and microplate readers and PCR detection systems for temperature measurements in the range of 35 to 95 °C. [ABSTRACT FROM AUTHOR]

A novel microstructure fiber based on side-polished fiber (SPF) was demonstrated. Polystyrene microspheres were self-assembled onto the side-polished surface of SPF to form the colloidal crystal cladding of the microstructure fiber. Because of the Bragg reflection of the colloidal crystals cladding and the strong interaction between evanescent field and colloidal crystal, three main valleys were observed in the transmission spectrum. The modulation amplitude of the valley was up to 12 dB. Furthermore, the transmission valley showed a high sensitivity of temperature. At the wavelength of 1524.25 nm-the position of valley, transmission optical power showed a maximum optical power variation of 14.7 dB in the range of 20-50 °C, the sensitivity of temperature was up to 0.487 dB/°C. The linear correlation coefficient was 99.84%. This SPF with colloidal crystals cladding shows a good potential in fiber sensing and other photonic applications. [ABSTRACT FROM AUTHOR]

A new multifunctional nanocomposite is described that displays both upconversion and downconversion luminescence. It is based on upconversion nanoparticles (UCNPs) with a mesoporous coating that is boned with a terbium(III) complex. The modified mesoporous nanocomposite was characterized by transmission electron microscopy, X-ray powder diffraction, nitrogen adsorption-desorption isotherms, and photoluminescence spectra. They display dual (green and red) fluorescence under 980-nm excitation, and green fluorescence under 365-nm excitation. Both emissions can be easily detected by bare eyes. The material has low cytotoxicity and good biocompatibility as proven by the methyl thiazolyltetrazolium (MTT) assay. The nanocomposite was successfully applied to upconversion luminescence based in-vitro confocal imaging of the cytosol of murine macrophage cells (RAW264.7), and this resulted in images of excellent contrast. In addition, the particles display strongly temperature-dependent luminescence in the range from 280 K to 330 K. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Silicon nanoparticles (Si NPs) with a diameter size ranging from 4 to 8 nm were successfully fabricated. They exhibit a visible photoluminescence (PL) due to the quantum confinement effect. Chemical functionalization of these Si NPs with alkyl groups allowed to homogeneously disperse them in nonpolar liquids (NPLs). In comparison to most of literature results for Si NPs, an important PL peak position variation with temperature (almost 1 meV/K) was obtained from 303 to 390 K. The influence of the liquid viscosity on the peak positions is also presented. These variations are discussed considering energy transfer between nanoparticles. The high PL thermal sensitivity of the alkyl-capped Si NPs paves the way for their future application as nanothermometers. [ABSTRACT FROM AUTHOR]

Microfluidic systems have been extensively applied in research of chemistry, biology and fluidic dynamics. In these applications, local and precise measurements are often crucial for reliable results. We demonstrate here a multilayered, multifunctional microfluidic platform with embedded electrodes open to the microchannel and thermocouple sensors underneath the microchannel that are suitable for local electrical and thermal measurements, respectively. We demonstrate that precise transport measurements with ac excitation frequency up to 1 MHz can be performed for electrolytes in centimeter-long microchannels. Local temperature sensing of the fluids in the microchannels can also be performed on this system. Such system can be either used to characterize local electrical and thermal properties of fluids, or applied to the study of thermal related electrokinetic phenomena, such as joule heat generation in dc conductance or temperature dependence of electrical transport. [ABSTRACT FROM AUTHOR]

Lithium-indium oxide is a high-density (5.9 g·cm), wide band-gap semiconductor with promising applications for scintillating detection of solar neutrinos as well as for efficient phosphorescence when doped with Er or Sm ions. In this report, we demonstrate visible upconversion emission of Er-doped LiInO synthesized by a simple solid-state chemistry procedure and discuss mechanisms responsible for pumping the Er ions to upper levels. Intense upconversion emission is observed in the green and red spectral regions under near-infrared excitation, and it is greatly enhanced by co-doping with Yb ions. We also examined the upconversion intensity change as a function of temperature, and, consequently, possible applications of this material as a low-temperature sensor. [ABSTRACT FROM AUTHOR]

Based on advantages of technology of distributive fiber-optic temperature sensing and specific to its applications in monitoring mine conflagration, the corresponding Processes such as connection arrangement, signal transmission and monitoring were illustrated. As applied in Sitai Coal Mine of Datong Coal Mine Group Co., this method is effective and accurate and could provide reliable gist for monitoring spontaneous combustion in gob area of mines. [ABSTRACT FROM AUTHOR]

ratiometric type of fluorescent nanoparticle was prepared via an encapsulation-reprecipitation method. By introducing an alkoxysilanized dye as a reference, the nanoparticles (NPs) give both a green and a red fluorescence under one single-wavelength excitation. The resulted ratiometric fluorescence is found to be highly temperature-dependent in the physiological range (25-45 °C), with an intensity temperature sensitivity of −4.0%/°C. Given the small size (20-30 nm in diameter) and biocompatible nature (silica out layer), such kind of NPs were very promising as temperature nanosensors for cellular sensing and imaging. [ABSTRACT FROM AUTHOR]

Chemical sensing, imaging and microscopy based on the use of fluorescent probes has so far been limited almost exclusively to the detection of a single parameter at a time. We present a scheme that can overcome this limitation by enabling optical sensing of two parameter simultaneously and even at identical excitation and emission wavelengths of two probes provided (a) their decay times are different enough to enable two time windows to be recorded, and (b) the emission of the shorter-lived probe decays to below the detectable limit while that of the other still can be measured. We refer to this new scheme as the dual lifetime determination (DLD) method and show that it can be widely varied by appropriate choice of probes and experimental settings. DLD is demonstrated to work by sensing oxygen and temperature independently from each other by making use of two probes, one for oxygen (a platinum porphyrin dissolved in polystyrene), and one for temperature [a europium complex dissolved in poly(vinyl methylketone)]. DLD was applied to monitor the consumption of oxygen in the glucose oxidase-catalyzed oxidation of glucose at varying temperatures. The scheme is expected to have further applications in cellular assays and biophysical imaging. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The novel integrated circuit (IC) temperature sensor presented in this paper works similarly as a two-terminal Zener, has breakdown voltage directly proportional to Kelvin temperature at 10 mV/°C, with typical error of less than±1.0°C over a temperature range from −50°C to +125°C. In addition to all the features that conventional IC temperature sensors have, the new device also has very low static power dissipation (0.5 mW), low output impedance (less than 1Ω), excellent stability, high reproducibility, and high precision. The sensor's circuit design and layout are discussed in detail. Applications of the sensor include almost any type of temperature sensing over the range of −50°C− +125°C. The low impedance and linear output of the device make interfacing the readout or control circuitry especially easy. Due to the excellent performance and low cost of this sensor, more applications of the sensor over wide temperature range are expected. [ABSTRACT FROM AUTHOR]

According to the temperature sensing model of the fiber Bragg grating (FBG), a theoretical method of temperature sensing capacity of FBG is proposed. Based on the temperature sensing model of FBG, a temperature sensing experiment was completed at liquid nitrogen temperature (−2196°C). The theoretical and experimental results were compared and analyzed, which show that at liquid nitrogen temperature or in a large-scope temperature sensing, the relationship between thermal variation ΔT and relative shift of reflected center wavelength ΔλB/λB of FBG is nonlinear and conic multinomial. [ABSTRACT FROM AUTHOR]