Non-contact Temperature Measurement Research Articles

Design and Construction of A Non-Contact Thermometer with Environmental Calibration for Health Monitoring

Fever is a common symptom of many infections, keeping monitoring devices like thermometers in constant demand. Temperature is an important vital sign for assessing acutely unwell individuals, and is measured frequently in primary care. However, non-contact measurement of temperature can be very challenging as majority of the temperature measuring devices require physical contact. As most diseases spread through human contacts and touching of surfaces, it is therefore very necessary to come up with ways that general hygiene can be more enhanced. It was upon this conviction that we have proposed this system, “Design and Construction of a Non-Contact Thermometer with Environmental Calibration for Health Monitoring”. This we achieved by interfacing MLX90614 Non-Contact Temperature Sensor Module with Arduino Nano Development Board as a microcontroller. The reading of this thermometer was made to display on a 1602 LCD Module that serves as our screen. The coding was done in Arduino IDE using C++ programming language. The systems is powered by a 5 V rechargeable DC source and have reliability of over 98% when compared with the standard thermometer found in the hospital.

Ultra-high-sensitive temperature sensing based on emission Pr3+ and Yb3+ codoped Y2Mo3O12 nanostructures

Non-contact optical temperature measurement has received considerable attention in recent years because of its benefits of high speed and safety.

Constructing Dual-Emitting via Energy Transfer in Sr2ScO3F:Mn4+,Nd3+ Phosphors For High-Performance Temperature Sensing.

The development of high-sensitivity thermometers has become increasingly important in recent years as the demand for noncontact optical temperature measurement has grown. Herein, we report a series of Sr2ScO3F:Mn4+,Nd3+ (SSOF:Mn4+,Nd3+) phosphors synthesized by the traditional high-temperature solid-state method for high-performance temperature sensing. Sr2ScO3F possesses a [ScO6F] octahedron and [SrO9F] tridecahedron, doped Mn4+ ions occupy the octahedral sites and emit deep red light at 650-750 nm, and doped Nd3+ ions occupy the tridecahedral sites and emit near-infrared light. Due to the energy transfer from the Mn4+ to Nd3+ ions, the SSOF:Mn4+,Nd3+ phosphor exhibits intense dual-center emissions. On the basis of the different thermal quenching behaviors of the Mn4+ and Nd3+ ions, high-sensitivity ratiometric thermometers can be achieved using fluorescence intensity ratio technology, and the high relative sensitivity (Sr) and absolute sensitivity (Sa) reached 3.40% K-1 (at 343 K) and 0.2580 K-1 (at 483 K), respectively. Our work not only studies the photoluminescence characteristics of SSOF:Mn4+,Nd3+ phosphors but also points out that SSOF:Mn4+,Nd3+ phosphors have important potential applications in optical temperature measurement.

Compact non-contact temperature measurement device for high-intensity microwave electromagnetic fields conditions

The practical implementation aspects of heated in microwave electromagnetic fields objects noncontact temperature measurement as one of the main factors in ensuring the quality of the heat-treated product are considered. The advantages of using the pyrometric method of temperature measurement in comparison with the thermocouple method under the influence of high-intensity electromagnetic fields are substantiated. A variant, which includes a cut-off waveguide with fasteners and a small-sized infrared sensor, for continuous temperature measurement system technical implementation of heated in a microwave field objects is proposed. The variants of proposed compact, cheap and versatile temperature measurement unit using a single-zone infrared sensor of the MLX90614 family, in application to conveyor microwave heating installations are described. The convenience of embedding the sensor into the microwave technological installation control system is noted due to the presence of programming functions for the emissivity of the measured object, the possibility of transmitting information about the object temperature using one of two digital protocols, as well as the possibility of building a network of several dozen measuring sensors on one two-wire digital data bus. The small size and weight, simplicity and relative cheapness of the contactless temperature measurement unit design allows it to be used in all types of microwave heating devices.

Multicolor luminescence and high efficient optical thermometric performance of Eu3+ and Sm3+ in self-activated Na2LuMg2V3O12 garnet

To develop efficient luminescence and optical thermometry materials for color display and non-contact temperature measurement, novel RE3+ (RE = Eu, Sm) doped self-activated Na2LuMg2V3O12 phosphors were prepared by a typical solid-state reaction method. Their crystal structure, morphology, multi-color luminescence and temperature sensing properties were elaborately investigated. Under UV light excitation, an intense and broad green-yellow emission band from VO43– group is observed in the Na2LuMg2V3O12 matrix, indicating its potential application in solid state lighting. After the incorporation of Eu3+ and Sm3+ ions, efficient energy transfer (ET) from VO43– group to Eu3+/Sm3+ ions occurs and the emission color of the samples can be readily tuned among different color ranges. Besides, based on the change of luminescence intensity and lifetimes of VO43– group in Na2LuMg2V3O12:Eu3+ and Na2LuMg2V3O12:Sm3+, the ET efficiency was analyzed and the mechanism is illustrated. Finally, large discrepancy between the thermal stability of VO43– group and Eu3+/Sm3+ ions are observed in the temperature-dependent emission spectra of Na2LuMg2V3O12:Eu3+ and Na2LuMg2V3O12:Sm3+. By taking advantage of the luminescence intensity ratio (LIR) between VO43– group and Eu3+/Sm3+ ions in Na2LuMg2V3O12:0.01Eu3+ and Na2LuMg2V3O12:0.07Sm3+, two new types of optical thermometry mediums were designed and their basic temperature sensing parameters were calculated.

Prominent cryogenic fluorescence temperature sensing and superior room-temperature photochromism in Bi/Eu codoped KNN transparent-ferroelectric ceramics

The growing demand for the miniaturization and multifunctionality of optoelectronic devices has promoted the development of transparent ferroelectrics. However, it is difficult for the superior multiple optical properties of these materials to be compatible with the excellent ferroelectricity and piezoelectricity in transparent ceramics. Here, we successfully synthesized Bi/Eu codoped eco-friendly K0.5Na0.5NbO3 transparent-ferroelectric ceramics with photoluminescence (PL) behavior, photochromic (PC) reactions and temperature-responsive PL. Based on the distinct optical properties of ceramics at different temperature ranges (room temperature and ultralow temperature), high utilization of multiple optical functions was realized. At room temperature, the PC behavior induced PL modulation contrast reaches 75.2% (at 592 nm), which can be applied in the optical information storage field. In the ultralow temperature range, the ceramics exhibit excellent sensitivity (with a maximum relative sensitivity of 26.32%/K) via fluorescence intensity ratio technology and exhibit great application potential in noncontact optical temperature measurements. Additionally, the change in the PL intensity at different wavelengths (I614/I592) can serve as a reliable indicator for detecting the occurrence of the phase transition from rhombohedral to orthorhombic at low temperature. This work provides a feasible paradigm for realizing the integration of ferroelectricity and multifarious optical properties in a single optoelectronic material.

Rb2InCl5·H2O doped with Te4+ for fluorescence thermometry and coordinated water-related structural phase transformation.

Here, we synthesized Rb2InCl5·H2O with x Te4+ doping by the coprecipitation method, which converts the original nonluminance for pure Rb2InCl5·H2O into orange luminescence ascribed to Te4+ incorporation with an emission peak at 648 nm and a full width at half maximum of 142 nm (420.3 meV) at room temperature. The photoluminescence (PL) lifetime of Te4+-doped Rb2InCl5·H2O exhibits a strong temperature dependence, with a maximum absolute sensitivity (SA) of 12 × 10-3 K-1 at 260 K and a relative sensitivity (SR) of 3.5%K-1 at 300 K, demonstrating its capability for non-contact remote temperature measurement. Additionally, we capture the dynamic changes of coordinated water with temperature in Rb2InCl5·H2O through temperature-dependent Raman spectroscopy, analyze the resulting structural phase transformation associated with coordinated water, and investigate the reversibility of this phase transformation.

Thermodynamic Calculations of the Main Characteristics of the Combustion Process of Pyrotechnic Nitrate-Metallized Mixtures with Additives of Organic and Inorganic Substances under External Thermal Influences

The aim of the article is to determine the dependencies of the combustion product temperatures of four-component mixtures, the content of high-temperature condensate, and unoxidized metal on the excess oxidizer coefficient, the number of additives, and external pressure using thermodynamic calculations. Modern methods of physicochemical analysis (such as cinephotography and microcinephotography methods, X-ray analysis methods, non-contact and contact temperature measurement methods), nonlinear thermal conductivity and thermal stability methods, as well as mathematical and experimental-statistical modeling, were employed to investigate the influence of elevated heating temperatures (up to 800 K) and external pressures (up to 107 Pa) on the ignition and combustion processes of pyrotechnic products. Standard pyrotechnic equipment was used to test pyrotechnic product samples under specified conditions. Calculations based on models were conducted in real-time and dialog mode on computer devices that meet modern requirements for the use of specialized software. The results of thermodynamic calculations are presented for the dependencies of combustion product temperatures of multicomponent pyrotechnic mixtures based on powders of metal fuels (magnesium, aluminium), nitrate oxidizer (sodium nitrate), additives of organic and inorganic substances (paraffin, sodium fluoride), and the content of high-temperature condensate and unoxidized metal depending on the excess oxidizer coefficient α = 0.1…4.0, the amount of paraffin additive εp = 0…0.2, sodium fluoride additive εf = 0…0.06, and external pressure P = 105…107 Pa. Based on the obtained results of thermodynamic calculations, statistical models in the form of regression dependencies of the specified combustion characteristics on their technological parameters and external conditions have been developed. These models enable the determination of fire hazardous properties of mixtures in real-time dialog and PC-based scenarios, considering premature initiation of products based on them under external thermal actions.

Modelling and Experimental Validation of the Flame Temperature Profile in Atmospheric Plasma Coating Processes on the Substrate

This work presents a characterisation model for the temperature distribution at different substrate depths during the atmospheric plasma spray (APS) coating process. The torch heat flow in this model is simulated as forced convection defined by a surface, a temperature profile, and a convection coefficient. The simulation model considers three plasma temperature profiles of the Al2O3 coating on a 5 mm thickness flat aluminium substrate. The simple and low-cost experimental procedure, based on a thermocouple, measures the plasma plume temperature distribution of the APS coating system, and their results are used to obtain the parameter values of each of the three proposed plasma temperature profiles. The experimental method for in situ non-contact temperature measurements inside the substrate is based on an infrared pyrometry technique and validates the simulation results. The Gaussian temperature profile shows excellent accuracy with the measured temperatures. The Gaussian approach could be a powerful tool for predicting residual stress through a coupled one-way thermal-mechanical analysis of the APS process.

Synthesis and upconversion color Tunability luminescence of K5Yb(MoO4)4 phosphor doped with Er3+and optical temperature sensing applications

A series of double molybdates with palmierite-related structure phosphors K5Yb1-x (MoO4)4:xEr3+ were synthesized by a solid-state method. It has been demonstrated that the K5Yb1-x (MoO4)4: xEr3+ phosphors are capable of exhibiting the characteristic green and red UC emission of Er3+ ions with excitation at 980 nm. Moreover, the green light emission is far more than the red light emission, so that the sample emits a powerful green light, which belongs to the two-photon absorption process. The upconversion efficiency is peaked when the content of Er3+ ions is 10 mol %. The optical thermometry properties of phosphors were explored by observing that the green UC emission intensity is temperature dependent. The maximum sensor sensitivity of the studied phosphor was discovered to be about 1.61%K−1 at the optimum doping concentration. And the phosphor is demonstrated to have high thermal stability by temperature cycling test. Eventually, a green light-emitting diode device was realized by using synthesized particles and a 980 nm near-infrared chip, which can emit a more obvious green light when the voltage reaches 1.80 V and the current can reach 800 mA, thus confirming its applicability in solid-state lighting. And the LED devices have been tested for life stability with little or no light degradation. These properties make the phosphors not only suitable for non-contact optical temperature measurement, but also able to be applied to solid state lighting.

Temperature distribution inversion in infrared multispectral imaging based on ensemble network.

Temperature distribution can be acquired through non-contact temperature measurement using multispectral imaging. However, the challenge lies in radiometric temperature inversion owing to the unknown emissivity. Despite the promising results demonstrated by traditional algorithms and neural networks, enhancing the precision and reliability of temperature inversion remains a challenge. To tackle these challenges, in this work, we propose the use of ensemble learning for temperature distribution inversion in infrared multispectral imaging. The network comprises a base-learner and a meta-learner, trained to establish the nonlinear relationship between temperature and multispectral distribution measurements. Moreover, the network architecture exhibits high robustness against noise arising in the testing environment. Simulations and real experiments on multispectral imaging measurements illustrate that ensemble learning can be a potent tool for multispectral imaging radiation temperature distribution measurement, achieving superior inversion performance compared to other neural networks. The reproducible code will be available at https://github.com/shuowenyang/Temperature-Inversion.

Background radiation compensation calibration method for film cooling infrared temperature measurement based on BP neural network

The precise non-contact temperature measurement method is essential for studying gas turbine component heat transfer. While infrared thermal imaging provides high-resolution two-dimensional temperature fields, errors arise from the measurement environment's complexity, emissivity variations, and reflection radiation effects. This study utilizes BP neural networks to correct infrared radiation on gas film cooled plates. By modeling background radiation and analyzing infrared emission processes, factors influencing temperature distribution are identified. Experimental data from uncooled plate are used for network training. Experimental measurements were conducted on uncooled plates to obtain training data. A BP neural network was established based on Planck's law and the radiation transmission process to relate the mainstream temperature to the background radiation. Calibration analysis was performed based on experimental data from the cooled plate, achieving the restoration of the two-dimensional temperature field under multiple operating conditions and significantly reducing measurement errors. This method comprehensively considers the entire process of radiation transmission, thereby eliminating background radiation embedded in the infrared images. The obtained measurement results vividly depict the real temperature distribution, offered significant support for gas turbine engineering applications.

Cation-substitution-induced high spectral tunability and thermosensitivity in double halide perovskite Cs2InCl5∙H2O

The advancement of non-contact temperature measurement has brought about significant interest due to its rapid response, broad applicability, and minimal thermal inertia. However, challenges such as spectral peak position modulation, sensitivity improvement, and reliable performance enhancement continue to persist in this field. In this study, a double halide perovskite single-crystal Cs2InCl5∙H2O was synthesized, with the introduction of Bi3+ ions modulating the photoluminescence from orange to blue. Meanwhile, the deep-blue emission peaked at 410 nm, boasting a high photoluminescence quantum yield (PLQY) of nearly 46 % under 340 nm excitation. Furthermore, by incorporating varying concentrations of Bi3+ ions, two distinct emission peaks were generated, facilitating effective signal differentiation for temperature detection. Utilizing the thermal quenching responses of these two emission peaks, a temperature-detection methodology based on the fluorescence intensity ratio (FIR) was developed, using donor-acceptor pair emission as detection signals and self-trapped emission as reference signals. The designed Cs2InCl5∙H2O:0.07Bi3+ exhibits a maximum Sa of 0.082 K-1 and Sr of 3.349 %K−1, respectively. The spectral adjustability and high sensitivity achieved through cation-substitution strategy in this study offer a promising pathway for the development of advanced optical thermometry materials with enhanced performance characteristics.

A novel single near-infrared luminescence of negative thermal quenching materials for optical temperature measurement

In recent years, upconversion (UC) luminescence has gained attention due to its unique optical properties, and the thermal response spectral characteristics of these materials have been widely utilized in various fields including temperature sensing and biomedical research. However, the photoluminescence (PL) intensity of most rare earth ions doped phosphors decreases with increasing temperature, and the visible fluorescence emission penetration is still limited. In the work, the pure phase of Yb3+ and Er3+ ions co-doped Sc2Mo3O12 was successfully prepared. The Sc2Mo3O12: Yb3+, Er3+ sample showed a single emission of UC near-infrared (NIR) light. The optimum doping concentrations of 0.2 for Yb3+ ions and 0.01 for Er3+ ions were achieved. The possible upconversion luminescence (UCL) mechanism was investigated by analysing the UCL spectra, the down-shift (DS) excitation and emission spectra of Sc2Mo3O12: Yb3+, Er3+ phosphor. The excitation path of NIR emission is mainly through Er3+ from 2H11/2 to 4I9/2 energy level. What's more, the temperature-dependent near-infrared UCL properties of sample is explored in the temperature range from 323 K to 673 K. The enhancement of upconversion luminescence intensity shows a linear relationship with increasing temperature. The study paves a new way for non-contact optical temperature measurement with single near-infrared UCL emission.

Advances in the application of non-contact temperature measurement technology for aero-engine blade.

The advancement of the aviation sector has made the temperature measurement technology for aero-engine turbine blades essential for maintaining the engine's safe and steady performance. The non-contact temperature measurement technology is a trending research focus in turbine blade temperature measurement due to its benefits of not requiring direct touch with the object being measured and its suitability for high-temperature and high-speed conditions. This paper provides a concise overview of various key non-contact temperature measurement methods for aero-engines, such as fluorescence temperature measurement, fiber-optic temperature measurement, and radiation temperature measurement. It discusses the temperature measurement principle, technical characteristics, and the current research status both domestically and internationally. Based on this, this Review further discusses the main challenges faced by the non-contact temperature measurement technology and the development trend of the future.

Bionic Microstructure‐Inspired Dual‐Mode Flexible Sensor with Photothermal Effect for Ultrasensitive Temperature and Strain Monitoring

AbstractFlexible dual‐mode sensors play a pivotal role in information exchange between humans and the environment. However, achieving dual‐mode sensing encompassing both flexibility and stretchability, while accurately quantifying stimulus signals such as temperature, remains a significant challenge. This paper presents a novel flexible dual‐mode strain/temperature sensor (DMSTS) that utilizes graphite powder (GR)/polyaniline (PANI)/silicone rubber composites, inspired by the bionic microstructure of a centipede's foot. The DMSTS exhibits an exceptional strain detection range (≈177%), and a low limit of detection (0.5% strain). Regarding temperature sensing, the DMSTS demonstrates a positive temperature coefficient effect within the range of 25–90 °C, with an ultrahigh sensitivity of 10.3 within the 75–90 °C range. Leveraging the photothermal characteristics of GR and PANI, the DMSTS holds significant promise for applications in human motion detection, infrared imaging, and photothermal effects. When integrated into an intelligent sensing system, it enables dynamic noncontact temperature measurement, human micro‐expression detection, and motion joint monitoring. Additionally, by incorporating a flexible thermochromic film with color‐changing ink, the DMSTS transforms temperature detection into a visually intuitive operation. With its versatile dual‐mode sensing capabilities, the DMSTS exhibits substantial potential in the fields of wearable electronics and healthcare.

Construction of multifunctional core-shell structure nanoprobe integrating NIR dual-mode optical thermometer and nuclear magnetic imaging

Precise temperature regulation and imaging are critical for in vivo photothermal treatment. The goal of this work is to realize non-contact temperature measurement and imaging in biological tissues by building a multifunctional nano-platform using optical temperature probes and imaging for biological diagnosis and therapy. Here, NIR dual-mode temperature probes of NaYF4: Nd/Yb/Gd@NaNdF4 were designed according to the LIR-I of 4F3/2 → 4I9/2/2F5/2 → 2F7/2 levels in 850 – 1025 nm and LIR-II of 2F5/2 → 2F7/2/4F3/2 → 4I11/2 in 950 – 1100 nm from the emissions of Nd3+/Yb3+. Transmission electron microscope (TEM) and X-ray diffraction (XRD) data of the sample demonstrate its superior dispersibility and accurate structure. The integrated intensity ratio centered around various luminescence intensity peaks is used as a temperature sensor since luminescence intensity is temperature-dependent. Additionally, the temperature sensing capabilities of two ratio temperature sensors were examined under 808 nm laser excitation, utilizing LIR (luminescence intensity ratio) technology. Furthermore, the MRI test indicated that the sample exhibited good imaging capacity when Gd3+ was added. These results assure the auspicious application prospects of the samples in temperature sensing, photothermal therapy, and biomedical imaging.

Sb3+ and Er3+ co-doped Cs2NaYCl6 double perovskite with ultra-high sensitivity for optical thermometry

Optical thermometry has attracted great attention because it enables accurate temperature measurement in harsh environments due to non-contact temperature measurement. Three-dimensional (3D) lead-free halide perovskites have a great application potential in this field, due to its outstanding luminous properties and stability. In this work, the Sb3+ and Er3+ are introduced in Cs2NaYCl6 double perovskites (DPs). The Sb3+ doping Cs2NaYCl6 DPs exhibits bright blue emission from the Sb3+ activated self-trapped excitons (STEs) and Sb3+,Er3+ co-doped Cs2NaYCl6 has efficient green emission with excellent photoluminescence quantum yields (PLQY) of 81.1% because of the presence of energy transfer from self-trapped excitons to Er3+ ions. Excitingly, the ratio between the fluorescence intensity at 524 nm and 550 nm (FIR(I524 nm/I550 nm)) and the ratio between the fluorescence intensity at 524 and 456 nm (FIR(I524 nm/I456 nm)) both have a high correlation with temperature in the range of 298–473 K. The maximum of relative sensitivity values reach to 1.18%/K (I524 nm/I550 nm) and 1.19%/K (I524 nm/I456 nm) at 298 K, respectively. The outstanding temperature sensitivity suggests that the Sb3+,Er3+ co-doped Cs2NaYCl6 has enormous application potential in ratiometric optical thermometry.

Fuzzy logic based thermal image processing for temperature monitoring of rotating cylindrical surfaces

When a non-contact and remote temperature measurement is of importance, several environmental factors must be considered. Of these, two are of crucial importance — the surface emissivity of the observed object and the directional emissivity in the object–sensor relationship. This paper proposes FDEM — a Fuzzy Directional Emissivity Model built with the assumption that the observed surface is cylindrically shaped. The model consists of two submodels — for vertical and horizontal directions separately. The main contribution of this paper is the formalization of a linguistic description of measurement conditions typical for an industrial environment. Additionally, dual linguistic fuzzy modifiers were used to increase the accuracy of the modeled emissivity. Finally, the proposed model achieved up to 40% reduction of RMSE error when used for correcting the temperature measurements of a rotating cylinder. Overall, our model provides a novel and reliable way for temperature readout correction on the entire surface of a drying roller, such as ones used in the papermaking industry. Furthermore, the proposed approach is not only inherently capable of compensating for the position of the camera, but also does it in an interpretable, and hence expert-verifiable, manner.

Promising lanthanide- NaYbF4:Er3+@NaYbF4:Tm3+ micro-phosphors for highly efficient upconversion luminescence and temperature sensing

In recent years, the fluorescence intensity ratio (FIR)-based technique for optical non-contact temperature measurement is of great interest to researchers due to its promising wide range of applications in high-voltage electricity fields, fires, corrosive environments, biological tissues, as well as other fields. Unfortunately, the FIR techniques based on thermally coupled energy levels (TCLs) often have the problem of low sensitivity as a result of the narrow energy gap. In contrast to FIR techniques with TCLs, the FIR technique with non-thermal coupled energy levels (NTCLs) is no longer restricted by the energy gap and is expected to achieve high signal resolution. In this study, we attempted to acquire a thermometric material that possesses high sensitivity as well as high signal resolution with the help of NTCLs. We successfully prepared NaYbF4:Er3+@NaYbF4:Tm3+ core-shell microcrystals by solvothermal technique using NaYbF4 as matrix and Er3+ and Tm3+ as luminescent centers and made necessary investigations on their crystal structures, microscopic morphologies, intrinsic mechanisms, and thermometric properties. The sample phosphors in a 980 nm laser show bright upconversion (UC) luminescence with emission peaks corresponding to the characteristic energy level jumps of Er3+ as well as Tm3+, respectively. The temperature sensing characteristic parameters have been investigated by FIR techniques with TCLs (2H11/2 → 4I15/2(Er3+)/4S3/2 → 4I15/2(Er3+)) & NTCLs (3H4→3H6(Tm3+)/1G4→3H6(Tm3+),3H4→3H6(Tm3+)/2H11/2 → 4I15/2(Er3+),3H4→3H6(Tm3+)/4S3/2 → 4I15/2(Er3+) and 3H4→3H6(Tm3+)/4F9/2 → 4I15/2(Er3+)), respectively. It is shown that the maximum absolute & relative sensitivities are 0.5677 K-1(495 K) as well as 1.20 % K−1(445 K) respectively with good thermal stability. In addition, the NTCLs have good separation of the emission bands, which enables the material to have excellent signal discrimination in temperature detection. These results indicate that the material is expected to be a potential candidate for optical thermometers.