Non-contact Temperature Research Articles

Temperature sensitive properties and preparation of europium complexes with double ligands

Temperature sensitive paints (TSPs) are a class of rising materials for non-contact temperature measurement technology. Efficient complexes with remarkable luminescent properties play the core role in TSPs. Rare earth organic complexes are often used as probe molecules for TSPs because of their long fluorescence lifetime, narrow fluorescence emission peaks, high fluorescence intensity, and large Stokes shift. Herein, two europium-based complexes, Eu(PCCA)3 phen and Eu (PMCA)3 phen, were synthesized under hydrothermal conditions, using europium(III) oxide (Eu2 O3 ), p-chlorocinnamic acid (PCCA), p-methoxy cinnamic acid (PMCA) and 1,10-phenanthroline (phen) as raw materials. Two temperature sensitive paints (Eu(PCCA)3 phen/PMMA and Eu(PMCA)3 phen/PMMA) were obtained by the polymerization of methyl methacrylate (MMA) with different europium complexes. The structure, morphology, luminescent properties of the europium complexes and temperature quenching properties of the TSPs were characterized by infrared (IR) spectroscopy, scanning electron microscopy (SEM), and fluorescence spectroscopy. The fluorescence results show that both of the two TSPs have good temperature quenching performance in the range 20-100°C with high sensitivity 50-60°C and 80-90°C, respectively. Furthermore, the highest sensitivity of Eu(PCCA)3 phen/PMMA is greater than that of Eu(PMCA)3 phen/PMMA. This work can provide a universal way for preparing efficient TSPs in practical applications.

Emissivity measurement of tungsten based on a double-wavelength infrared thermometer between 140 and 500℃

At present, most Tokamak devices adopt non-contact temperature measurements for the first wall using an infrared thermometer. Tungsten is regarded as the most likely plasma-facing material, especially as the divertor target, in future Tokamka devices. Accordingly, it is important to obtain accurate emissivity of tungsten for accurate temperature measurement of the divertor target plate and ensuring steady operation of Tokamak devices. In this work, a set of emissivity measurement equipment with a self-designed double-wavelength colorimetric infrared thermometer is established, and a method of emissivity measurement based on double-wavelength colorimetry considering background radiation is proposed. The normal spectral emissivity of tungsten with wavelengths of 10.2 μm and 10.8 μm between 140 and 500℃ in the same working environment as the Tokamak devices is measured after calibrating the optical splitter and the infrared thermometer by using a blackbody furnace. The measurement results indicate that the normal spectral emissivity of tungsten ranges from 0.0936 to 0.1246 between 140 and 500℃ in a vacuum environment. The emissivity increases with the increase of temperature, and the relative increase rate is 33.12%. Finally, the uncertainty of the emissivity measurement results is calculated, which ranges from 0.0444 to 0.0767. The normal spectral emissivity of tungsten measured based on the double-wavelength colorimetric principle proposed in this paper provides a good reference for the accurate temperature measurement of the divertor target plate in Tokamak devices. It also provides a reference for the measurement of metal emissivity with background radiation under similar vacuum conditions.

Contact and Non-Contact Temperature Acquisition Sensors: A Review

Contact and Non-Contact Temperature Acquisition Sensors: A Review

Photoluminescence and optical temperature measurement of Mn4+/Er3+ co-activated double perovskite phosphor through site-advantageous occupation

Because traditional methods based on thermal coupling energy level temperature measurement have large errors, a new temperature sensing strategy is proposed to attain strong sensitivity and excellent signal resolution ability. The rare-earth and also transition metal ions with poles apart thermal quenching channels are used as dual emission centers to find a suitable host to achieve high-efficiency dual-mode emission. In this work, a string of phosphors with NaLaMgWO6 (NLMW) as the host, the single-doped and double-doped Mn4+ and Er3+ phosphors were adopted by the traditional high temperature solid-state reaction method. The crystallographic structure of the phosphor was analyzed by X-ray power diffraction and Rietveld refinement methods, and the results showed that a pure double perovskite phosphor with a monoclinic structure was successfully prepared. The photoluminescence excitation and emission spectrum properties, CIE chromaticity coordinates and photoluminescence spectra at different temperatures are detailed studied. Excited by ultraviolet light (300 nm), corresponding to the 4A2→4T1 transition of Mn4+ and the charge transfer from O2– to W6+ of Er3+. There is no energy transfer between Mn4+ and Er3+. NLMW:Mn4+/Er3+ phosphors were especially sensitive to temperature changes within the scope of 303 K to 523 K. As the temperature increases, the fluorescence intensity of Mn4+ is thermally quenched faster than Er3+. The luminescent intensity ratio of Er3+ thermal coupling level and the FIR of Er3+/Mn4+ are used to study the temperature performance. The results show that the maximum relative sensitivity of FIR up to 1.31% K−1, which is higher than the maximum temperature sensitivity based on the thermal coupling energy level, and which is beyond most of the non-contact temperature measurement materials previously reported, confirming that NLMW:Mn4+/Er3+ phosphors have application potential in non-contact temperature measurement.

Approaches to improve the accuracy of measurement of human body temperature by contactless IR thermometers

Purpose: analyze existing approaches to measuring human body temperature, propose approaches to improve measurement accuracy.
 Methodology. analytical, experimental.
 Findings. The article considers approaches to improving the accuracy of measuring body temperature with non-contact infrared thermometers. The parameters of infrared temperature meters are analyzed. The composition of the system for collecting statistical information on the influence of environmental factors on the accuracy of measurements is proposed. Research software is offered. Measurement statistics are given. Ways to increase the accuracy of measurements with non-contact infrared thermometers are indicated. Mathematical and physical support of non-contact temperature measurement is offered, the analysis of parameters of infrared body temperature meters is carried out, the system for receiving the statistical information for revealing of factors of influence is developed, the analysis of results is carried out.
 Originality. An updated formula for determining body temperature is proposed, which contains the following parameters: specific constant for a particular device, which depends on the optical focusing system and the absorbing material; the degree of radiation of the object, which depends on the material of the object whose temperature is measured; the absolute temperature of the object being measured; absolute ambient temperature; reflected radiation from the environment; absolute temperature of the pyrometer sensor housing..
 Practical value. The paper offers recommendations that can significantly increase the accuracy of measurements in the design of systems containing infrared thermometers.

A high-brightness phosphor based on Yb[formula omitted]/Er[formula omitted] codoped Y2O3 micro-crystals and controllable temperature sensing sensitivity via rare earth ions

Non-contact temperature detection technology based on the fluorescence intensity ratio (FIR) of rare earth ions has attracted much attentions due to its high sensitivity and operability. Herein, Yb3+/Er3+:Y2O3 micro-crystals with different rare earth ion concentrations were prepared and studied. Under 980 nm excitation, the influences of rare earth ion concentration on fluorescence intensity and temperature sensing sensitivity are discussed in detail. The prepared Yb3+/Er3+ codoped Y2O3 micro-crystals possess excellent fluorescence properties, its temperature sensing sensitivity is superior and the maximum absolute sensitivity is up to 0.0078 K−1 at 625 K. The strongest fluorescence intensity and highest sensitivity are achieved in 3.0Yb3+/0.3Er3+:Y2O3 and 3.0Yb3+/0.1Er3+:Y2O3 crystals, respectively. So it is necessary to evaluate doping design for better applications. This work may further promote the optical thermometry research and provide a new strategy to increase the temperature detection sensitivity.

Overview of N-Rich Antennae Investigated in Lanthanide-Based Temperature Sensing.

The market share of noncontact temperature sensors is expending due to fast technological and medical evolutions. In the wide variety of noncontact sensors, lanthanide-based temperature sensors stand out. They benefit from high photostability, relatively long decay times and high quantum yields. To circumvent their low molar light absorption, the incorporation of a light-harvesting antenna is required. This Review provides an overview of the nitrogen-rich antennae in lanthanide-based temperature sensors, emitting in the visible light spectrum, and discusses their temperature sensor ability. The N-rich ligands are incorporated in many different platforms. The investigation of different antennae is required to develop temperature sensors with diverse optical properties and to create a diverse offer for the multiple application fields. Molecular probes, consisting of small molecules, are first discussed. Furthermore, the thermometer properties of ratiometric temperature sensors, based on di- and polynuclear complexes, metal-organic frameworks, periodic mesoporous organosilicas and porous organic polymers, are summarized. The antenna mainly determines the application potential of the ratiometric thermometer. It can be observed that molecular probes are operational in the broad physiological range, metal-organic frameworks are generally very useful in the cryogenic region, periodic mesoporous organosilica show temperature dependency in the physiological range, and porous organic polymers are operative in the cryogenic-to-medium temperature range.

Photoluminescence and optical temperature sensing properties of Dy3+-doped Na0.5Bi0.5TiO3 multifunctional ferroelectric ceramics

A series of Dy3+ doped Na0.5Bi0.5TiO3 (NBT: xDy3+, x = 0.003–0.018) lead-free ferroelectric ceramics were successfully prepared by a solid-state reaction method. The Dy3+ ions composition dependent photoluminescence properties were systematically studied. All the samples display intense characteristic emission of Dy3+ under an excitation wavelength of 454 nm, which are attributed to the transitions of 4F9/2 → 6HJ/2 (J = 13, 11 and 9). All the samples show strong orange-yellow emission, which could be applied to warm white light hopefully. When the content of Dy3+ is equal to 0.012, the ceramic has the optimal luminous performance. Remarkable thermal quenching of the luminous intensity ceramic occurs as the temperature is higher than initial temperature 293 K. Furthermore, Dy3+ activated photoluminescence performance combined with the presence of ferroelectricity in the NBT host can be applied to developing non-contact optical temperature sensitive materials and other future novel optoelectronic devices.

An open-source non-contact thermometer using low-cost electronic components

Due to the spread of COVID-19 across the world and the increased need for non-contact thermometers to prevent the spread of disease, a new electronic thermometer has been designed and implemented for measuring human body temperature from a distance. This device is currently in use at building entrances to measure the body temperatures of employees, students, and customers. This system is designed using low-cost easy-to-assemble open-source electronic components. The system consists of seven main parts: an Arduino UNO microcontroller, an infrared (IR) thermometer for non-contact temperature measurements (GY-906 MLX90614ESF module), an IR motion sensor (TCRT 5000) for the purpose of contactless initiation of the system, a graphic LCD to display results, a DS3231 clock module for a real-time clock and calendar, and a micro-SD storage board to store device audio instructions.

In-situ non-contact high-temperature measurement of an optical fiber up to the glass softening point.

The optical fiber itself can function as a partially reflecting concentric cavity interferometer when transversely probed by a focused laser beam. In this study, the thermal response of the fiber heated by a CO2-laser beam was characterized by monitoring the back-scattered interference pattern. Simultaneous measurement of the Bragg wavelength shift of an inscribed, high-temperature stable fiber Bragg grating allowed for calibration of the temperature-dependent phase response of the interferometer. The presented technique allows for in-situ non-contact temperature measurements up to the glass softening point.

Photoluminescence properties of Er3+ and Eu3+ ions based on oxide host for optical temperature sensing with high sensitivity

Motivated from increasing demands of non-contact optical temperature sensing, the Yb3+-Er3+ and Eu3+ doped NaY9Si6O26 (NYS) oxide phosphors were designed by high-temperature solid-state reaction method. The phase purity of the as-prepared samples was checked from XRD patterns. For the upconversion luminescence in NYS:Yb3+,Er3+, the optimal Er3+ doping content was determined to be 1 mol%, and the characteristic emission peaks of Er3+ were observed in the region of 500–700 nm. In Eu3+ activated NYS phosphors, it has been found that the emissions originating in 5D1 and 5D0 levels demonstrate different change tendencies in intensity with Eu3+ doping concentration. By studying the temperature-dependent luminescent spectra, it was indicated that the emissions intensities from different excited states of Er3+ change differently with temperature. Two kinds of fluorescence intensity ratio (FIR) strategies were used in NYS:10%Yb3+,1%Er3+, containing thermally-coupled levels and non-thermally-coupled levels. In the NYS:3%Eu3+ phosphor, it was found that the FIR for 577 and 536 nm emissions follows a linear relation with temperature. The high sensitivities in the present phosphors indicate the potential application in optical temperature sensing.

Development of Noncontact Body Temperature Monitoring and Prediction System for Livestock Cattle

Annually, numerous cattle die of various diseases, necessitating the need for effective cattle health management. To ensure cattle disease detection at an early stage and identify the health status of cattle, we collected the environment temperature, humidity, illuminance, and infrared images of cattle in an actual-life environment as input parameters to develop an artificial intelligence characterization module for measuring deep body temperature in a contactless manner. By analyzing the correlation of estimating deep body temperature at the horn, eyeball, and nose of cattle, the most effective way of estimating this temperature was found to be at the horn. The estimation accuracy was particularly high in the sitting state. Moreover, we proposed a noncontact measurement system that can approximately measure the moving distance of cattle and depict the cattle movement trajectory. The usability and reliability of the proposed systems were verified via an experiment using special feed. We used moving distance data as an additional input for the body temperature estimation system and found that rumen temperature can be accurately estimated. The body temperature estimated using the proposed system can be used to realize long-term remote monitoring of cattle health and early and timely abnormality detection.

Microwave-assisted infrared thermography: A tool for quality assessment of blast furnace feeds

Infrared thermography is a ubiquitous technique for surface non-contact temperature profile analysis and monitoring. The generated thermograms offer a plethora of applications in non-destructive evaluation (NDE) for detecting inhomogeneities in engineering structures. However, the potential of this technique is still in its infancy for quality assessment of minerals and ores. In steel plants, iron ore and coke are the most important raw materials fed into the blast furnace. The alumina content in iron ore and moisture percentage in coke play a significant role in determining ultimate product quality and blast furnace efficiency. Till date, plant operators have relied on time-consuming and cumbersome chemical analysis methods for quality analysis of ores. The present investigation reveals a microwave-assisted infrared thermography based non-invasive technique for fast and accurate quality evaluation of blast furnace feed material, in terms of alumina content in iron ores and moisture content in coke. The estimation of alumina content is based on the difference in dielectric constants of various iron ore constituents. Moisture analysis in coke involves the utilization of well-known black body radiation. The co-relation factor for the alumina content in iron ore is slightly lower than the moisture content in coke. The basic difference occurs owing to inherent limitation of the technique for two different substances. Such type of novel approach is scanty in open domain literature. This non-invasive, real time, precise and fast technique proved its enormous potential during validation for random plant samples and thus promising to improve feed quality and blast furnace efficiency.

Noncontact Body Temperature Measurement: Uncertainty Evaluation and Screening Decision Rule to Prevent the Spread of COVID-19.

The need to measure body temperature contactless and quickly during the COVID-19 pandemic emergency has led to the widespread use of infrared thermometers, thermal imaging cameras and thermal scanners as an alternative to the traditional contact clinical thermometers. However, limits and issues of noncontact temperature measurement devices are not well known and technical–scientific literature itself sometimes provides conflicting reference values on the body and skin temperature of healthy subjects. To limit the risk of contagion, national authorities have set the obligation to measure body temperature of workers at the entrance to the workplace. In this paper, the authors analyze noncontact body temperature measurement issues from both clinical and metrological points of view with the aim to (i) improve body temperature measurements accuracy; (ii) estimate the uncertainty of body temperature measurement on the field; (iii) propose a screening decision rule for the prevention of the spread of COVID-19. The approach adopted in this paper takes into account both the traditional instrumental uncertainty sources and clinical–medical ones related to the subjectivity of the measurand. A proper screening protocol for body temperature measurement considering the role of uncertainty is essential to correctly choose the threshold temperature value and measurement method to access critical places during COVID-19 pandemic emergency.

Eu3+-doped ratiometric optical thermometers: Experiment and Judd-Ofelt modelling

Rare earth-doped materials are successfully utilized as non-contact optical temperature sensors. Thermal sensing is usually based on the ratiometric technique between two separate emission lines originated from thermally-coupled levels. We study Gd 2 O 3 :Eu 3+ 1 at.% and YAG: Eu 3+ 4 at.% phosphors as luminescence thermometers in 298–473 K range using both conventional experimental and Judd-Ofelt based theoretical approaches. Thermometric performances of suggested sensors were quantified through absolute and relative thermal sensitivities and temperature resolution. Experiment and theoretical modelling gave similar results. This proves the theoretical model as a simple and fast method for estimation of the Eu 3+ -doped thermometer perspectives. • Eu 3+ -doped phosphors were synthesized via different modified Pechini methods. • Gd 2 O 3 :Eu 3+ and YAG:Eu 3+ nanopowders were used as contactless luminescence thermometers. • Thermometric performances were estimated through thermal sensitivities and temperature resolution. • Experimental approach and Judd-Ofelt based theoretical model give similar results.

Color-tunable emission and non-contact optical temperature sensing performance in NaY9Si6O26: Ce3+, Eu3+ phosphors

In this article, the tunable-color emission properties of Ce3+/Eu3+ in NaY9Si6O26 phosphors were reported. Ce3+ and Eu3+ ions had effectively incorporated the sites of Na+ and Y3+ ions, which were revealed by Rietveld refinements. The site occupation preference of Ce3+ in cationic sites were discussed. The energy transfer from Ce3+ to Eu3+ ion under the 312 nm excitation was ascribed to dipole-dipole interaction mechanism based on Dexter's energy transfer theory of multipolar interaction, which makes NaY9Si6O26: Ce3+, Eu3+ produce tunable-color emission. Additionally, the temperature dependent emission spectra of the powders were studied. Temperature sensing performances were reflected by the fluorescence intensity ratio based on different temperature dependent variation tendency of Ce3+ and Eu3+ ions. The maximum values of the absolute and relative sensor sensitivities of NaY9Si6O26: Ce3+, Eu3+ phosphors were about 0.0328 K−1 and 0.95 % K−1, respectively. Above all, NaY9Si6O26: Ce3+, Eu3+ phosphors show a promising prospect for optical thermometer applications.

Promising lanthanide-doped BiVO4 phosphors for highly efficient upconversion luminescence and temperature sensing.

The semiconductor oxide BiVO4 has been intensively studied as a highly efficient photocatalyst. Here we attempt to adopt trivalent lanthanide (Ln3+)-doped BiVO4 as a novel upconversion luminescence (UCL) material for achieving high-efficiency UCL and temperature sensing under near-infrared (NIR) irradiation. Er3+/Tm3+, Yb3+/Er3+, and Yb3+/Tm3+ ions were selected to co-dope the BiVO4 phosphors, achieving three primary colors of red, green, and blue (RGB) with high color-purity. At an optimal doping concentration, the upconversion quantum yield of the BiVO4:8%Yb3+,18%Er3+ phosphor reaches as high as 2.9%. Furthermore, we, for the first time, demonstrate the non-contact temperature sensing properties of a BiVO4:Er3+,Tm3+ phosphor via employing fluorescence intensity ratio technology. The results show that the maximum absolute thermal sensitivity is ≈70 × 10-4 K-1 at 473 K under 980 nm excitation, with high and stable sensitivity of more than 60 × 10-4 K-1 over a wide temperature range of 333-493 K. In addition, at a much safer wavelength of 1550 nm, this sample achieves maximum absolute sensitivity of 56 × 10-4 K-1 at 453 K. Moreover, the BiVO4:Er3+,Tm3+ phosphor presents high relative sensitivity of about 1.1% K-1 under both 980 and 1550 nm excitation at 293 K. These results indicate that the BiVO4 semiconductor oxide can be used as a novel host to achieve high UCL efficiency and promising thermal sensing performance, suggesting potential applications in the new fields of anti-counterfeiting, displays, and non-contact temperature sensors.

A broadband optical pH sensor using upconversion luminescence

A non-contact optical pH and temperature sensor of the surrounding fluid medium based on the luminescence of an optically trapped single upconversion nanoparticle inside a microfluidic channel.

非接触式面部穴位温度检测系统的设计

非接触式面部穴位温度检测系统的设计

Non-contact prefrontal cortex temperature estimation method trained by a deep body thermometer

Non-contact prefrontal cortex temperature estimation method trained by a deep body thermometer