Near-infrared Thermography Research Articles

The Application of 2d Mxene Nanosheet -Based Thermosensitive Gel Delivery System Loaded with Cisplatin and Imiquimod for Lung Cancer.

Lung cancer's high incidence and dismal prognosis with traditional treatments like surgery and radiotherapy necessitate innovative approaches. Despite advancements in nanotherapy, the limitations of single-treatment modalities and significant side effects persist. To tackle lung cancer effectively, we devised a temperature-sensitive hydrogel-based local injection system with near-infrared triggered drug release. Utilizing 2D MXene nanosheets as carriers loaded with R837 and cisplatin (DDP), encapsulated within a temperature-sensitive hydrogel-forming PEG-MXene@DDP@R837@SHDS (MDR@SHDS), we administered in situ injections of MDR@SHDS into tumor tissues combined with photothermal therapy (PTT). The immune adjuvant R837 enhances dendritic cell (DC) maturation and tumor cell phagocytosis, while PTT induces tumor cell apoptosis and necrosis by converting light energy into heat energy. Material characterization employed transmission electron microscopy, X-ray photoelectron spectroscopy, phase transition temperature, and near-infrared thermography. In vitro experiments assessed Lewis cell proliferation and apoptosis using CCK-8, Edu, and TUNEL assays. In vivo experiments on C57 mouse Lewis transplant tumors evaluated the photothermal effect via near-infrared thermography and assessed DC maturation and CD4+/CD8+ T cell ratios using flow cytometry. The in vivo anti-tumor efficacy of MDR@SHDS was confirmed by tumor growth curve recording and HE and TUNEL staining of tumor sections. The hydrogel exhibited excellent temperature sensitivity, controlled release properties, and high biocompatibility. In vitro experiments revealed that MDR@SHDS combined with PTT had a greater inhibitory effect on tumor cell proliferation compared to MDR@SHD alone. Combining local immunotherapy, chemotherapy, and PTT yielded superior anti-tumor effects than individual treatments. MDR@SHDS, with its simplicity, biocompatibility, and enhanced anti-tumor effects in combination with PTT, presents a promising therapeutic approach for lung cancer treatment, offering potential clinical utility.

Infrared Thermal Profiles in Silvopastoral and Full-Sun Pastures in the Eastern Amazon, Brazil

There is a great need to identify interactions among silvopastoral systems and microclimatic indicators that describe the effect of trees compared to conventional pasture systems without trees. The objective of this study was to evaluate thermal conditions in a silvopastoral system and a pasture area exposed to full sunlight in the eastern Amazon, Brazil. The silvopastoral system was composed of the forest tree species Bertholletia excelsa H.B.K., Dipteryx odorata (Aubl.) Willd, and Khaya grandifoliola C.DC.. During the monitoring period, a forest inventory was carried out that included 30 trees from each species for which thermal profiles were created using a high-precision thermographic camera. Near-infrared thermography showed a positive and direct correlation with dendrometric variables. Silvopastoral systems with K. grandifoliola reduced the heat profile the most compared to conditions in a pasture fully exposed to sunlight, which demonstrates the ecosystem service provided by trees for thermal regulation in these systems. The microclimatic conditions explain the greater presence of bovines in the silvopastoral system as they were most likely in search of the thermal comfort provided by the trees during the period of the highest daytime temperatures. The silvopastoral system benefits the caloric balance and thermal comfort of pasture animals.

Contactless thermal mapping of high-temperature solar receivers via narrow-band near-infrared thermography

We present the design, construction, and successful proof-of-principle demonstration of a thermal camera capable of seeing through glass and other radiatively participating media, and apply the device to map the temperature distribution of a steam-filled windowed solar cavity receiver operating at temperatures up to 1400 °C. This “glass piercing” thermal camera utilizes a narrow bandpass filter with a center wavelength of 772 nm to effectively see through glass and similar optical glazing materials, as well as infrared-active radiatively participating media, to allow direct contactless measurement of the inner surfaces of windowed cavity receivers. By utilizing a standard optical CMOS sensor, the device achieves much higher resolution at a lower cost than traditional thermal cameras operating in the mid-infrared. Using a calibrated photometry sphere, we experimentally determined the device sensitivity (grayscale value per spectral radiance value), which allows the spectral radiance and ultimately temperature to be determined from a simple grayscale image. The calibrated device was then applied to both a blackbody source operating at above 1000 °C, and a high-temperature solar cavity receiver operating above 1400 °C. The results serve as an experimental proof-of-concept for glass-piercing and radiatively-participating-gas-piercing thermography.

Measuring both thermal and kinematic full-fields using a single CMOS camera during high temperature tests

In numerous domains, both kinematic and thermal fields are sought to study temperature dependent phenomena. They are usually obtained by digital image correlation and infrared thermography, respectively. Although these techniques are well mastered, their combination is not straightforward since they need radically different conditions to work efficiently. This paper presents a procedure to measure accurately thermal and kinematic full-fields simultaneously using a single CMOS camera in a chosen region of interest. The kinematic field is measured by global digital image correlation and the thermal field by near-infrared thermography for temperatures above 700 ∘C. A procedure is detailed to identify the radiometric model and compute the thermal field without being affected by the heterogeneous emissivity of the sample surface caused by the speckle pattern. A methodology showing how to manage temperature measurements during high thermal transients is also presented. The proposed approach aims to be widely accessible since it does not need strong knowledge in DIC algorithms and only requires a standard camera. The method is first validated on a virtual test case, before being used on real experiments performed at high temperature with a stereo setup.

Continuous and non-invasive thermography of mouse skin accurately describes core body temperature patterns, but not absolute core temperature

Body temperature is an important physiological parameter in many studies of laboratory mice. Continuous assessment of body temperature has traditionally required surgical implantation of a telemeter, but this invasive procedure adversely impacts animal welfare. Near-infrared thermography provides a non-invasive alternative by continuously measuring the highest temperature on the outside of the body (Tskin), but the reliability of these recordings as a proxy for continuous core body temperature (Tcore) measurements has not been assessed. Here, Tcore (30 s resolution) and Tskin (1 s resolution) were continuously measured for three days in mice exposed to ad libitum and restricted feeding conditions. We subsequently developed an algorithm that optimised the reliability of a Tskin-derived estimate of Tcore. This identified the average of the maximum Tskin per minute over a 30-min interval as the optimal way to estimate Tcore. Subsequent validation analyses did however demonstrate that this Tskin-derived proxy did not provide a reliable estimate of the absolute Tcore due to the high between-animal variability in the relationship between Tskin and Tcore. Conversely, validation showed that Tskin-derived estimates of Tcore reliably describe temporal patterns in physiologically-relevant Tcore changes and provide an excellent measure to perform within-animal comparisons of relative changes in Tcore.

Application of silicon-based camera for measurement of non-homogeneous thermal field on realistic specimen surface

The high-cost low-resolution infrared cameras operating in middle infrared spectral ranges are widely used to detect the thermal fields. In this study, a low-cost high-resolution silicon-based sensor camera operating in near infrared spectral ranges is used to perform the observation of the thermal fields on the realistic steel specimen surface. In near-infrared spectral ranges, a small temperature variation led to a large modification in the sensor illumination, inducing acquired images with over saturation or poor dynamic range of gray levels. To address this problem, an algorithm was used to precisely adjust the exposure time to acquire images with constant gray level whatever the temperature evolution is, and then used in heating experiment of a steel specimen. Results showed that images with constant gray level could be acquired during the heating experiment. A special radiometric model was used to perform near-infrared thermography. Based on this radiometric model of steel specimen surface, the thermal fields on steel specimen surface were successfully reconstructed without measuring surface emissivity.

Validation of a multimodal set‐up for the study of zirconium alloys claddings' behaviour under simulated LOCA conditions

AbstractIn a previous paper, Campello et al. presented a combined experimental/numerical approach to identify the creep behaviour of as‐fabricated Zircaloy‐4 claddings under simulated LOCA conditions. The current paper deals with the uncertainties and errors estimation of the two key methods used to measure the thermal and kinematic full fields during the creep tests: near infrared thermography (NIRT) and two‐dimensional digital image correlation (2D‐DIC).The NIRT uncertainties are evaluated as 0.7% of the actual temperature. They are mainly due to the thermocouple measurements used to calibrate the radiometric model of the NIRT.A combined 2D‐DIC/edge detection approach is proposed to quantify the error related to 2D‐DIC when measuring the ballooning of the tubular specimen. The 2D‐DIC error is evaluated as 0.1% of the actual equivalent strain even for ballooning inducing a radius increase of 20%.

On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Model Development and Validation

Powder-bed beam-based metal additive manufacturing (AM) such as electron beam additive manufacturing (EBAM) has a potential to offer innovative solutions to many challenges and difficulties faced in the manufacturing industry. However, the complex process physics of EBAM has not been fully understood, nor has process metrology such as temperatures been thoroughly studied, hindering part quality consistency, efficient process development and process optimizations, etc., for effective EBAM usage. In this study, numerical and experimental approaches were combined to research the process temperatures and other thermal characteristics in EBAM using Ti–6Al–4V powder. The objective of this study was to develop a comprehensive thermal model, using a finite element (FE) method, to predict temperature distributions and history in the EBAM process. On the other hand, a near infrared (NIR) thermal imager, with a spectral range of 0.78 μm–1.08 μm, was employed to acquire build surface temperatures in EBAM, with subsequent data processing for temperature profile and melt pool size analysis. The major results are summarized as follows. The thermal conductivity of Ti–6Al–4V powder is porosity dependent and is one of critical factors for temperature predictions. The measured thermal conductivity of preheated powder (of 50% porosity) is 2.44 W/m K versus 10.17 W/m K for solid Ti–6Al–4V at 750 °C. For temperature measurements in EBAM by NIR thermography, a method was developed to compensate temperature profiles due to transmission loss and unknown emissivity of liquid Ti–6Al–4V. At a beam speed of about 680 mm/s, a beam current of about 7.0 mA and a diameter of 0.55 mm, the peak process temperature is on the order around 2700 °C, and the melt pools have dimensions of about 2.94 mm, 1.09 mm, and 0.12 mm, in length, width, and depth, respectively. In general, the simulations are in reasonable agreement with the experimental results with an average error of 32% for the melt pool sizes. From the simulations, the powder porosity is found critical to the thermal characteristics in EBAM. Increasing the powder porosity will elevate the peak process temperature and increase the melt pool size.

Evaluations of temperature measurements in powder-based electron beam additive manufacturing by near-infrared thermography

Powder-based electron beam additive manufacturing (EBAM) has received an increased attention from different industries for various applications. Process metrology such as part temperature measurements is essential to process model validations as well as process monitoring. However, temperature measurements in EBAM are challenging because of high temperature ranges, extreme gradients and fast transient response, etc. In this study, temperature measurements during the EBAM process were attempted using a near-infrared (NIR) thermal camera. The thermal camera was able to capture the pre-heating, contour melting, and hatch melting events. The best obtained spatial resolution is around 12 μm. Moreover, temperature data were processes and analysed to illustrate the process phenomenon, analogy to a moving heat source event. Moreover, from the extracted temperature profiles, a melting range can be identified and utilised for melt pool geometry estimates. It is shown that a typical melt pool in hatch melting from this test is about 1.91 mm long and 0.63 mm wide.

Dynamic and static thermal study of micromachined heaters: the advantages of visible and near-infrared thermography compared to classical methods

We report on the dynamic and static thermal characterization of microsystems using a visible and near-infrared (NIR) thermography system based on a low-cost standard CCD sensor. The interest of this method is that it is possible to obtain a true spatial resolution better than 500 nm, which is necessary in high spatial resolution applications (microsystem applications). Another interesting point of this optical method is that the temperature error versus the emissivity error is always very low (compared to infrared thermography). We show, in this study, that this behavior originates in the high sensitivity of Planck's law in this wavelength range (compared to infrared range). Thus, we demonstrate the principal advantages of this method for micromachined heater application. Thermal measurements (in dynamic and static modes) were performed on micro-heaters commonly used in microsystems, platinum- and silicon-based micromachined heaters. The results show the capability of the method in terms of the thermal resolution and spatial resolution as well as the capacity to quickly obtain static and dynamic thermal images of the studied sample.

Near-infrared thermography using a charge-coupled device camera: Application to microsystems

Using near-infrared thermography microscopy and a low-cost charge-coupled device (CCD) camera, we have designed a system which is able to deliver quantitative submicronic thermal images. Using a theoretical model based on Planck's law and CCD sensor properties allowed us to determine a minimal theoretical detection temperature and an optimal temperature sensitivity of our system. In order to validate this method, we show a good relationship between a theoretical study and a thermal measurement of a microsample.

Thermography of target plates with near-infrared optical fibres at Tore Supra

First spectroscopic near-infrared thermography measurements in the range 0.9–1.95 μm performed with optical fibres are reported. Two set-ups served as test-beds for physical and technical questions for a security system based on fibre optical thermography. It was found that for the interesting temperature range above 600°C atomic and molecular line emission is negligible in comparison with thermal radiation. The observed near-infrared spectra are however different from simple blackbody radiation curves. They are explained by the coverage of the surface with dust and flakes. The dust particles are identified by their spectral emissivity falling off with the square of the wavelength. On one set-up, flakes were identifiable by fast cool-down times and confirmed by post-experiment inspection. In the absence of flakes, surface temperatures on a ripple protection plate were measured, that allowed to determine the mean energy of ripple trapped ions to be 200–300 keV.