Temperature Calibration Curve Research Articles

Micro-Spectrometer-Based Interferometric Spectroscopy and Environmental Sensing with Zinc Oxide Thin Film

This study introduces a novel approach for analyzing thin film interference spectra by employing a micro-spectrometer equipped with a spectral chip. Focusing on zinc oxide (ZnO) thin films prepared via the sol–gel method, this research aims to explore the films’ physical properties through spectral analysis. After obtaining the interference spectrum of the ZnO thin films, the peak positions within the spectrum were cataloged. Mathematical simulation was used to adjust the refractive index and thickness of the films to match the simulated interference peak positions with the observed peak positions. The thickness of the prepared ZnO film was estimated to be 4.9 μm and its refractive index at 80 °C was estimated to be 1.96. In addition, the measurement system was used to detect environmental changes, including temperature changes and gas exposure. It was observed that the optical characteristics of ZnO films exhibit marked variations with temperature shifts, enabling the establishment of a temperature calibration curve based on spectral feature displacement. In addition, experiments using a variety of gases showed that NO2 and gaseous isopropanol significantly affect the interference spectrum of ZnO, with the peak of the interference spectrum shifted by 2.3 nm and 5.2 nm, respectively, after injection of the two gases. This indicates that interferometric spectroscopy can serve as an effective tool for ZnO monitoring, capable of selectively detecting specific gases.

Mechanism of Seebeck coefficient variation at the output of NiCr/NiSi thin film thermocouple with different wires

In this paper, by using magnetron sputtering to prepare NiCr/NiSi thin film thermocouples, the static calibration method is used for NiCr/NiSi thermocouples with rapid temperature calibration experiments. Different temperature calibration curves are obtained. The Seebeck coefficient of NiCr/NiSi thin film thermocouples connected to NiCr/NiSi wires is significantly higher (41.39 μV/°C) than that of NiCr/NiSi wires (0 μV/°C). The Seebeck coefficient (41.39 μV/°C) of the NiCr/NiSi thin-film thermocouple connected to copper wire is significantly higher than that of the thermocouple connected to copper wire (0 μV/°C). The problem of the Seebeck coefficient of the K-type thermocouple is analyzed by experimental data, which provides the relevant parameter basis for the use of the K-type thermocouple. The method has the advantages of simple equipment, convenient operation, accurate and reliable data, and provides a basis for the sensor to measure the temperature measurement.

Mayan Fire: Calibration curve for the determination of heating temperatures of limestone, lime and related materials by FTIR measurements

A controlled heating experiment has been carried out on selected geological limestone samples obtained from the Yucatan peninsula to establish a heating temperature calibration curve for the determination of heating temperatures through Fourier Transform Infrared Spectroscopy (FTIR-ATR) ratios of υ2/υ4 peak intensities. This curve – the first produced in the Mayan area – will greatly benefit the study of the lime calcination technology employed by the ancient Maya society. This model was then applied to the study of an archaeological pit-kiln located on the northern Maya lowlands, allowing us to describe the temperature distribution at which the limestones were exposed within the structure, and consequently providing insights on the lime manufacturing process and the control of fire achieved by this culture.

Bi3+ and Tb3+ Co-doped Cs2AgInCl6 Lead-free double perovskite nanocrystals for detection of temperature and copper ions

The content of Cu2+ in lubricating oil and lubricant temperature are important indicators predicting mechanical failure. Therefore, developing a nontoxic fluorescence probe is necessary to detect Cu2+ and temperature in lubricating oil. The lead-free inorganic double perovskite nanocrystals (NCs) Cs2AgInCl6 are potential candidates. However, the low fluorescence intensity and the high excitation energy required of Cs2AgInCl6 NCs limit their practical applications. In this study, Bi3+ and Tb3+ were successfully co-doped into Cs2AgInCl6 NCs via the hot-injection method. The doping of Bi3+ produces a broad emission originating from self-trapped excitons and reduces the excitation energy, allowing commercial LEDs as excitation sources. Tb3+ ions doping offers characteristic emission peaks (5D0-7FJ) of Tb3+ ions and improves the fluorescence intensity of Cs2AgInCl6 NCs. Furthermore, the Cs2AgInCl6: Bi3+/Tb3+ NCs have been employed as optical thermometry, which provide a temperature calibration curve with the maximum absolute and relative sensitivities of 2.15% K−1 at 350 K and 2.25% K−1 at 303 K in the temperature range of 303–423 K, respectively. Finally, the nanocrystals have been applied to detect Cu2+ in lubricating oil. The fluorescent probe shows a good detection sensitivity of 8.94 × 10-4 nM−1 and a low detection limit of 14.3 nM in the range of 10–300 nM. This work not merely offers a novel way for improving the luminescence performances of double perovskite NCs Cs2AgInCl6, but broadens their potential for detection of Cu2+ and temperature.

Optical transition properties, internal quantum efficiencies, and temperature sensing of Er3+ doped BaGd2O4 phosphor with low maximum phonon energy

AbstractThe hosts with low maximum phonon energy (MPE) are preferred since the nonradiative consumption of the luminescence centers in them are low. Among the low MPE hosts, the oxide ones are more favored owing to their excellent stability and easy synthesis. In this work, the optical and spectroscopic properties of BaGd2O4:Er3+ phosphor were studied. The MPE of BaGd2O4 host was observed from Eu3+ phonon sideband (PSB) spectrum and Raman spectrum to be 477 cm−1 which does not second to the fluoride hosts. The refractive index, which is indispensable for Judd–Ofelt calculation, was confirmed from the both approaches of the Eu3+‐probe and the band gap energy, and the similar refractive indices were confirmed, therefore the average refractive index 2.01 was used in the Judd–Ofelt calculation. The Judd–Ofelt parameters of Er3+ in BaGd2O4 host was confirmed to be = 7.91 × 10−21 cm2, = 2.36 × 10−21 cm2, and = 9.00 × 10−22 cm2. Furthermore, the internal quantum efficiencies for 4F9/2 and 4IJ (J = 9/2, 11/2, and 13/2) levels were determined. Finally, the optical temperature sensing properties were studied in detail, and the temperature calibration curve was experimentally derived, meanwhile the maximum absolute sensitivity was confirmed to be 0.0028 K−1.

Sustainable Smart Tags with Two‐Step Verification for Anticounterfeiting Triggered by the Photothermal Response of Upconverting Nanoparticles

Quick‐response (QR) codes are gaining much consideration in recent years due to their simple and fast readability compared with conventional barcodes. QR codes provide increased storage capacity and safer access to information, fostering the development of optical or printed smart tags as preferred tools for the Internet of Things (IoT). Herein, the combination of Yb3+/Er3+‐doped NaGdF4upconverting nanoparticles (UCNPs) with recovered plastic for the fabrication of sustainable screen‐printed QR codes is reported. Their photothermal response under distinct power densities of the 980 nm laser irradiation (15–115 W cm−2) induces color‐tuning and temperature sensing. This power dependence is exploited to design a double key molecular keylock accessed by a smartphone camera through the red (R), green (G), and blue (B) (RGB) additive color model and upconversion thermometry. The latter is based on the integrated areas of the2H11/2→4I15/2and4S3/2→4I15/2Er3+transitions using the interconnectivity and integration into the IoT network of the mobile phone to download the temperature calibration curve of the UCNPs from a remote server. These findings illustrate the potential of QR codes‐bearing UCNPs toward the design of smart tags for mobile optical sensing and anticounterfeiting.

Cambios ambientales en los últimos 1800 años en el manglar de Neguanje, Parque Nacional Natural Tayrona, Caribe colombiano

We reconstructed changes in vegetation and climate conditions during the last 1800 years in a column of sediment 4 m deep (Playa Pozo sector, Neguanje Bay, Tayrona National Natural Park, department of Magdalena, Colombia). We characterized the main components (mineral elements, organic matter), micro-stratigraphy (types of organic matter), humidity variations (%), organic and inorganic carbon, and palynological associations (specifically pollen grains), and counted spores of fungi, algae, ferns, plant debris, and insects. The palynological associations (dominant elements) were defined and related to the current types of vegetation. The definition of the dominant groups in the palynological spectrum and their relationship with the current vegetation types was associated with the stratigraphic conditions of the sediments to detect the changes that occurred during this period. In the reconstruction of the paleoenvironments, we determined the relationship between the defined palynological associations and the stratigraphy of the sediments, the humidity (precipitation), and the covered area. For this purpose, we used the temperature calibration curves of the last 2000 years proposed by various authors. We did not recover enough palynomorphs at the base of the column between 400 and 380 cm deep (2000-1693 years BP), but organic components of marine origin predominated in the sediment, a condition associated with a warm period in the central and eastern Colombian Caribbean coastal environments. In zone I (1693-1294 years B.P.), the mangrove was consolidated and in zone II (1294-1078 years A.P.), it expanded with the vegetation of flooded areas. In zone III (1078-654 years B.P.), we detected the occurrence of the greatest mangrove development, especially by the dominant species Rhizophora mangle. In zones IV and V (654 years A.P.-present), the mangrove cover decreased. This period was less warm than the previous ones, similar to the prevailing conditions in the Ciénaga Grande de Santa Marta and its surroundings.

On-Line Measurement of Chip Temperature Based on Blocking Leakage Current of the Insulated-Gate Bipolar Transistor Module in the High-Temperature Reverse-Bias Test

In high-temperature reverse-bias test of an insulated-gate bipolar transistor module, the problem of self-heating in chip resulting from power loss arises with high frequency. To address this problem, the law of the variation in leakage current with temperature for the reverse-bias state of a device is derived and utilized to establish a temperature calibration curve, with which the online measurement of the insulate-gate bipolar transistor module chip temperature can be implemented directly by real-time monitoring of device leakage current in high-temperature reverse-bias test. The method we proposed solves the problem of large measurement error in chip temperature obtained by traditional thermal resistance calculation method. In addition, real-time chip temperature can be monitored without introducing additional test circuit or HTRB interruption experiment. To demonstrate the effectiveness of the proposed method, the switching small-current temperature measurement method is used to make comparison, and the experiment result indicates that the temperature of the chip in the blocking test can be obtained with high precision by using the leakage current measurement method presented in this work.

Thermomagnetometric analysis of nickel–zinc ferrites

In this paper, magnetic phase transitions of nickel–zinc ferrites (Ni1−xZnxFe2O4) with a zinc content of 0 ≤ xZn ≤ 0.7 were studied using the thermomagnetometric method, which is a thermogravimetric analysis with a constant magnetic field applied. The studied ferrites were made from oxide powders using ceramic technology. The Curie point was determined from the derivative thermogravimetric curve in the region of magnetic phase transition. The Curie temperature calibration curve was obtained against the degree of doping of nickel ferrite with zinc to detect the magnetic phases by the Curie temperature. Thermal analysis of multicomponent magnetic mixtures that consist of nickel–zinc ferrites with different zinc contents was performed. The dependence of the change in mass during magnetic phase transition on the mass content of the magnetic phase in the ferrite mixture was revealed.

Research on Online Junction Temperature Measurement of MOSFET Devices

In order to detect the MOSFET junction temperature, the paper measures the MOSFET junction temperature by electrical method without affecting the normal operation of the devices and the circuits. In addition, the method of optimizing the temperature calibration curve proposed is helpful for engineers to efficiently monitor the junction temperature and prevent the risk of failure caused by high temperature.

Unusual oxygen detection by means of a solid state sensor based on a CaZr0.9In0.1O3–δ proton-conducting electrolyte

This work reports the unusual results on studying the operability and capability of a solid state electrochemical sensor based on a proton-conducting material to analyze the oxygen concentration in a gas media at elevated temperatures. This sensor consists of two ceramic parts made of CaZr0.9In0.1O3–δ, one of which acts as a hydrogen pump element, while another as a potentiometric detection element. A limiting current, occurring at a certain voltage value applied to the former element, is a sensor's response; it forms the concentration or temperature calibration curves, which can be used for the subsequent electrochemical analysis at high temperatures. The presented results expand the possibilities for utilizing the proton-conducting materials in new electrochemical (analytical) directions.

Influence of excitation power and doping concentration on the upconversion emission and optical temperature sensing behavior of Er3+: BaGd2(MoO4)4 phosphors

Generally, the effects of excitation power and dopant concentration on the optical temperature sensing behaviors of rare earth (RE) doped materials based on the fluorescence intensity ratio (FIR) technique are disregarded. In this paper, Er3+: BaGd2(MoO4)4 phosphors with different concentrations were fabricated by the high temperature solid-state reaction method. The results show that the variation of FIR (2H11/2/4S3/2) with excitation power is not only related to the laser-induced heating effect, but also the diverse power-dependences of 2H11/2 and 4S3/2 levels. Consequently, the temperature calibration curves change at different excitation power densities. When the calibration curve obtained at a low power density is applied to estimate the temperature of the object excited at a high power density, a large overestimate of the temperature rise induced by the optical heating effect can be caused. Besides, the temperature sensing sensitivity depends on the Er3+ doping concentration, which increases first with concentration to a maximum and then reduces. The maximal absolute sensitivity is ~110.5 × 10−4 K−1 in 5mol% Er3+: BaGd2(MoO4)4 phosphor, which is among the highest values of RE ions doped phosphors based on thermally coupled levels recorded before.

Raman scattering in single-crystal sapphire at elevated temperatures.

Sapphire is a widely used high-temperature material, and this work presents thorough characterization of all the measurable Raman scattering modes in sapphire and their temperature dependencies. Here, Raman scattering in bulk sapphire rods is measured from room temperature to 1081°C and is illustrated as a method of noncontact temperature measurement. A single-line argon ion laser at 488nm was used to excite the sapphire rods inside a cylindrical furnace. All the anti-Stokes peaks (or lines) were observable through the entire temperature range of interest, while Stokes peaks were observable until they were obscured by background thermal emission. Temperature measurements were found to be most reliable for A1g and Eg modes using the peaks at ±418, ±379, +578, +645, and +750 cm-1 (+ and - are designated for Stokes and anti-Stokes peaks, respectively). The 418 cm-1 peak was found to be the most intense peak. The temperature dependence of peak position, peak width, and peak area of the ±418 and ±379 peaks is presented. For +578, +645, and +750, the temperature dependence of peak position is presented. The peaks' spectral positions provide the most precise temperature information within the experimental temperature range. The resultant temperature calibration curves are given, which indicate that sapphire can be used in high-temperature Raman thermometry with an accuracy of about 1.38°C average standard deviation over the entire >1000°C temperature range.

Spectroscopic Signatures of Sub-Second Laser-Calcined Dy3+-Doped Oxide Precursors for Use in ex Situ Thermal Impulse Sensors

We measure the phase-dependent spectroscopic signatures—photoluminescence (PL) emission spectrum, PL excitation spectrum, and PL lifetime—of three different heat treated Dy3+-doped oxide precursors (TiO2, Y2O3, and ZrO2), which are calcined at temperatures ranging from 440 to 1256 K for 100 ms. On the basis of these spectroscopic measurements we compute temperature calibration curves, which correlate a given spectroscopic signature to a specific calcination temperature. We find that the emission/excitation spectra-based calibration curves for a given material, in general, have the same transition temperature within uncertainty, but the lifetime-based calibration curve is found to transition at a lower temperature. This difference is due to the emission/excitation-based curves depending on crystallization of the oxide hosts, while the lifetime changes due to the decomposition of the precursor compound, which eliminates some PL quenchers, including high energy O–H, C–O, and C–O2 vibrations. The observation of two different kinetic phenomenon in a single oxide host has promising applications in ex situ thermal impulse sensors, which have uses in explosive fireballs, combustion science, and arson investigations.

Upconverting Nanoparticles Working As Primary Thermometers In Different Media

In the past decade, noninvasive luminescent thermometry has become popular due to the limitations of traditional contact thermometers to operate at scales below 100 μm, as required by current demands in disparate areas. Generally, the calibration procedure requires an independent measurement of the temperature to convert the thermometric parameter (usually an intensity ratio) to temperature. A new calibration procedure is necessary whenever the thermometer operates in a different medium. However, recording multiple calibrations is a time-consuming task, and not always possible to perform, e.g., in living cells and in electronic devices. Typically, a unique calibration relation is assumed to be valid, independent of the medium, which is a bottleneck of the secondary luminescent thermometers developed up to now. Here we report a straightforward method to predict the temperature calibration curve of any upconverting thermometer based on two thermally coupled electronic levels independently of the medium, dem...

Technical Note: A safe, cheap, and easy-to-use isotropic diffusion MRI phantom for clinical and multicenter studies.

Since Diffusion Weighted Imaging (DWI) data acquisition and processing are not standardized, substantial differences in DWI derived measures such as Apparent Diffusion Coefficient (ADC) may arise which are related to the acquisition or MRI processing method, but not to the sample under study. Quality assurance using a standardized test object, or phantom, is a key factor in standardizing DWI across scanners. Current diffusion phantoms are either complex to use, not available in larger quantities, contain substances unwanted in a clinical environment, or are expensive. A diffusion phantom based on a polyvinylpyrrolidone (PVP) solution, together with a phantom holder, is presented and compared to existing diffusion phantoms for use in clinical DWI scans. An ADC vs. temperature calibration curve was obtained. ADC of the phantom (808 to 857 ± 0.2 mm2 /s) is in the same range as ADC values found in brain tissue. ADC measurements are highly reproducible across time with an intra-class correlation coefficient of > 0.8. ADC as function of temperature (in Kelvin) can be estimated as ADCm(T)=[exp(-7.09)·exp-2903.81T-1293.55] with a total uncertainty (95% confidence limit) of ± 1.7%. We present an isotropic diffusion MRI phantom, together with its temperature calibration curve, that is easy-to-use in a clinical environment, cost-effective, reproducible to produce, and that contains no harmful substances.

Using Signal Processing Techniques to Enhance the Temperature Measurements Using Nanohole Array Sensors

A signal processing approach to reducing noise in the observed transmission through nanohole array sensors used in a microscale calorimeter is presented. The results demonstrate that using rectification and moving average processes, a well-defined Extraordinary Optical Transmission (EOT)-temperature calibration curve can be developed in the presence of a moving light fringe pattern.

Graphene as a photothermal actuator for control of lipid mesophase structure.

The optical density of pristine graphene is high and broad in the near infrared region of the electromagnetic spectrum positioning this material as a highly efficient photothermal agent for in vivo applications. In this study, surfactant assisted exfoliated graphene was incorporated within bulk lipid samples of varying lipid types: glyceryl monoether, glyceryl monooleate and phytantriol. The pristine graphene sheets did not disrupt the packing of the liquid crystals while being in sufficiently intimate contact to provide localized heating and induce phase transitions. The phase progressions induced through heating using NIR irradiation of the entrained graphene particles within the bulk liquid crystal were studied using SAXS and confirmed using polarized optical microscopy. Increases in apparent temperature experienced by the matrix of up to 50 °C were observed by establishing a SAXS versus bulk temperature calibration curve allowing in situ measurements. The studies demonstrate the potential for use of graphene as a photothermal actuator across a range of lipid based systems of interest in controlled drug delivery.

Imaging technique for real-time temperature monitoring during cryotherapy of lesions.

Noninvasive real-time temperature imaging during thermal therapies is able to significantly improve clinical outcomes. An optoacoustic (OA) temperature monitoring method is proposed for noninvasive real-time thermometry of vascularized tissue during cryotherapy. The universal temperature-dependent optoacoustic response (ThOR) of red blood cells (RBCs) is employed to convert reconstructed OA images to temperature maps. To obtain the temperature calibration curve for intensity-normalized OA images, we measured ThOR of 10 porcine blood samples in the range of temperatures from 40°C to ?16°C and analyzed the data for single measurement variations. The nonlinearity (?Tmax) and the temperature of zero OA response (T0) of the calibration curve were found equal to 11.4±0.1°C and ?13.8±0.1°C, respectively. The morphology of RBCs was examined before and after the data collection confirming cellular integrity and intracellular compartmentalization of hemoglobin. For temperatures below 0°C, which are of particular interest for cryotherapy, the accuracy of a single temperature measurement was ±1°C, which is consistent with the clinical requirements. Validation of the proposed OA temperature imaging technique was performed for slow and fast cooling of blood samples embedded in tissue-mimicking phantoms.

Luminescence thermometry via the two-dopant intensity ratio of Y2O3:Er3+, Eu3+

In this work we investigated the photoluminescence properties of Y2O3:Er3+, Eu3+ as a function of temperature and the possibility to use this material as a temperature sensor. Photoluminescence emission measurements with 532 nm laser excitation were recorded in the temperature range from 303 up to 573 K. The measured intensity ratio of erbium 4S3/2 → 4I15/2 and europium 5D0 → 7F2 emission lines was used for determination of the temperature calibration curve. These emission lines are intense, narrow and well defined. The distance between the lines, being 47 nm, can be easily measured even with a low-resolution spectrometer. The calculated relative sensitivity of the temperature sensor was 1.4% K−1 at 303 K, in the physiological temperature range, meaning that it could be successfully applied in biological studies.