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Shape memory polymer resonators as highly sensitive uncooled infrared detectors
摘要： Uncooled infrared detectors have enabled the rapid growth of thermal imaging applications. These detectors are predominantly bolometers, reading out a pixel’s temperature change due to infrared radiation as a resistance change. Another uncooled sensing method is to transduce the infrared radiation into the frequency shift of a mechanical resonator. We present here highly sensitive resonant infrared sensors, based on thermo-responsive shape memory polymers. By exploiting the phase-change polymer as transduction mechanism, our approach provides 2 orders of magnitude improvement of the temperature coefficient of frequency. Noise equivalent temperature difference of 22 mK in vacuum and 112 mK in air are obtained using f/2 optics. The noise equivalent temperature difference is further improved to 6 mK in vacuum by using high-Q silicon nitride membranes as substrates for the shape memory polymers. This high performance in air eliminates the need for vacuum packaging, paving a path towards flexible non-hermetically sealed infrared sensors.
关键词： resonant infrared sensors,uncooled infrared detectors,thermal imaging,shape memory polymers,phase-change polymer
更新于2025-09-16 10:30:52
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Optical gas imaging with uncooled thermal imaging camera - impact of warm filters and elevated background temperature
摘要： The goal of the presented study was to investigate the impact of warm filters and elevated background temperature on the operation of an uncooled wideband camera used for optical gas imaging (OGI). The Noise Equivalent Temperature Difference (NETD) parameter was measured for a VOx wideband OGI camera built for the purpose of the experiments, with and without an interference filter. The results demonstrate that warm filters have a clear effect on the performance of the OGI camera. Based on the standard NETD measurement procedures, a Camera-Scene Noise Equivalent Temperature Difference (CSNETD) parameter is proposed to quantify both the camera and scene noise. The CSNETD measurements are used to evaluate the impact of elevated background temperature on the performance of the OGI camera. Finally, the camera is used to image methane leaks in the MWIR and LWIR bands. The results are consistent with the presented NETD/CSNETD measurements and confirm the impact of warm filters and elevated background temperature on the operation of the uncooled thermal imaging camera.
关键词： optical gas imaging,warm filter,thermal imaging camera,gas leaks,humidity
更新于2025-09-12 10:27:22
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Non-invasive diagnosis of viability in seeds and lichens by infrared thermography under controlled environmental conditions
摘要： Background: Non?invasive procedures for the diagnosis of viability of plant or fungal tissues would be valuable for scientific, industrial and biomonitoring purposes. Previous studies showed that infrared thermography (IRT) enables non?invasive assessment of the viability of individual "orthodox" (i.e. desiccation tolerant) seeds upon water uptake. However, this method was not tested for rehydrating tissues of other desiccation tolerant life forms. Furthermore, evaporative cooling could obscure the effects of metabolic processes that contribute to heating and cooling, but its effects on the shape of the "thermal fingerprints" have not been explored. Here, we further adapted this method using a purpose?built chamber to control relative humidity (RH) and gaseous atmosphere. This enabled us to test (i) the influence of relative humidity on the thermal fingerprints during the imbibition of Pisum sativum (Garden pea) seeds, (ii) whether thermal fingerprints can be correlated with viability in lichens, and (iii) to assess the potential influ? ence of aerobic metabolism on thermal fingerprints by controlling the oxygen concentration in the gaseous atmos? phere around the samples. Finally, we developed a method to artificially "age" lichens and validated the IRT?based method to assess lichen viability in three lichen species. Results: Using either 30% or 100% RH during imbibition of pea seeds, we showed that "live" and "dead" seeds produced clearly discernible "thermal fingerprints", which significantly differed by > |0.15| °C in defined time windows, and that RH affected the shape of these thermal fingerprints. We demonstrated that IRT can also be used to assess the viability of the lichens Lobaria pulmonaria, Pseudevernia furfuracea and Peltigera leucophlebia. No clear relationship between aerobic metabolism and the shape of thermal fingerprints was found. Conclusions: Infrared thermography appears to be a promising method for the diagnosis of viability of desiccation? tolerant tissues at early stages of water uptake. For seeds, it is possible to diagnose viability within the first hours of rehydration, after which time they can still be re?dried and stored until further use. We envisage our work as a baseline study for the use of IR imaging techniques to investigate physiological heterogeneity of desiccation tolerant life forms such as lichens, which can be used for biomonitoring, and for sorting live and dead seeds, which is potentially useful for the seed trade.
关键词： Viability,Desiccation tolerance,Stress,Seeds,Thermal imaging,Lichen
更新于2025-09-12 10:27:22
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Infrared thermography and ulcer prevention in the high‐risk diabetic foot: data from a single‐blind multicentre controlled clinical trial
摘要： Aim To assess the usefulness of monthly thermography and standard foot care to reduce diabetic foot ulcer recurrence. Methods People with diabetes (n=110), neuropathy and history of ≥1 foot ulcer participated in a single-blind multicentre clinical trial. Feet were imaged with a novel thermal imaging device (Diabetic Foot Ulcer Prevention System). Participants were randomized to intervention (active thermography + standard foot care) or control (blinded thermography + standard foot care) and were followed up monthly until ulcer recurrence or for 12 months. Foot thermograms of participants from the intervention group were assessed for hot spots (areas with temperature ≥2.2°C higher than the corresponding contralateral site) and acted upon as per local standards. Results After 12 months, 62% of participants were ulcer-free in the intervention group and 56% in the control group. The odds ratios of ulcer recurrence (intervention vs control) were 0.82 (95% CI 0.38, 1.8; P=0.62) and 0.55 (95% CI 0.21, 1.4; P=0.22) in univariate and multivariate logistic regression analyses, respectively. The hazard ratios for the time to ulcer recurrence (intervention vs control) were 0.84 (95% CI 0.45, 1.6; P=0.58) and 0.67 (95% CI 0.34, 1.3; P=0.24) in univariate and multivariate Cox regression analyses, respectively. Conclusions Monthly intervention with thermal imaging did not result in a significant reduction in ulcer recurrence rate or increased ulcer-free survival in this cohort at high risk of foot ulcers. This trial has, however, informed the design of a refined study with longer follow-up and group stratification, further aiming to assess the efficacy of thermography to reduce ulcer recurrence.
关键词： ulcer prevention,diabetic foot ulcer,thermal imaging,neuropathy,thermography
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 22nd International Conference on Intelligent Engineering Systems (INES) - Las Palmas de Gran Canaria, Spain (2018.6.21-2018.6.23)] 2018 IEEE 22nd International Conference on Intelligent Engineering Systems (INES) - High Resolution 3D Thermal Imaging Using FLIR DUO R Sensor
摘要： With the spread of photogrammetry processes, photo-based 2D/3D reconstruction became general, in research as well as in the industry. Source images are taken using either a hand-held camera or an automated camera fixed to the carrier, a UAV, then they are matched during post-processing. The price of digital microbolometer-based high-resolution (1 megapixel) thermal cameras is currently very high, but these, compared to RGB cameras (16-20 megapixel), are still considered to have very low-resolution, in this way employing photogrammetry in this present case is not feasible. In the article, a novel method developed by us is introduced which by using a low thermal resolution camera (FLIR DUO R), based on which a 3D thermal image can be produced with the help of a camera capable of dual imaging (RGB and Thermal). The work is illustrated using measurements, and post-production was conducted using the MATLAB software. The process is adequate for producing 3D thermal images taken using UAV devices.
关键词： FLIR,photogrammetry,large scale point cloud,MATLAB,object reconstruction,3D thermal imaging
更新于2025-09-10 09:29:36
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Lanthanide-Based Thermometers: At the Cutting-Edge of Luminescence Thermometry
摘要： Present technological demands in disparate areas, such as microfluidics and nanofluidics, microelectronics and nanoelectronics, photonics and biomedicine, among others, have reached to a development such that conventional contact thermal probes are not accomplished anymore to perform accurate measurements with submicrometric spatial resolution. The development of novel noncontact thermal probes is, then, mandatory, contributing to an expansionary epoch of luminescence thermometry. Luminescence thermometry based on trivalent lanthanide ions has become very popular since 2010 due to the unique versatility, stability, and narrow emission band profiles of the ions that cover the entire electromagnetic spectrum with relatively high emission quantum yields. Here, a perspective overview on the field is given from the beginnings in the 1950s until the most recent cutting-edge examples. The current movement toward usage of the technique as a new tool for thermal imaging, early tumor detection, and as a tool for unveiling the properties of the thermometers themselves or of their local neighborhoods is also summarized.
关键词： Luminescent Nanothermometers,Early Tumor Detection,Luminescence Thermometry,Lanthanide-Based Thermometers,Thermal Imaging
更新于2025-09-10 09:29:36
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Detection of Delaminations in Sunlight-Unexposed Concrete Elements of Bridges Using Infrared Thermography
摘要： Infrared thermography is a non-destructive test used in the inspection of structures. However, its use for bridge inspection is still under development and in many cases its application may be limited to bridge sections exposed to direct sunlight. This study aims to evaluate infrared thermography test for the detection of delaminations in different types of concrete not exposed directly to sunlight. The experimental methodology uses two concrete specimens with water/cement ratios (w/c) equal to 0.5 and 0.6, through the insertion of polystyrene plates of different thicknesses (3, 6 and 12 mm) and depths (25, 50 and 75 mm), in order to simulate defects within the concrete and evaluate the capacity of infrared thermography to detect them. The results show that detection is possible, but limited to short periods of time. In relation to the concrete quality, defects were more easily detected in the test specimen with lower w/c ratio. It can be said that the nearer to the surface and larger the delamination, the easier it is to detect. Also, the better the quality of the concrete, the more effective the technique becomes.
关键词： Concrete,Passive thermal imaging,Infrared thermography,Bridge inspection
更新于2025-09-10 09:29:36
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Deep Learning For Pyrolysis Reactor Monitoring: From Thermal Imaging Towards Smart Monitoring System
摘要： Monitoring the operation of a pyrolysis reactor is always challenging due to the extremely high operating temperature (over 800?C) in the ?red furnace. To improve current monitoring capability, a monitoring framework is proposed that builds upon thermal photography to provide a detailed view inside the ?red furnace. Based on the infrared images generated from the temperature data provided by cameras, a deep learning approach is introduced to automatically identify tube regions from the raw images. The pixel-wise tube segmentation network is named Res50-UNet, which combines the popular ResNet-50 and U-Net architectures. By this approach, the precise temperature and shape on pyrolysis tubes are monitored. The control limits are eventually drawn by the adaptive k-nearest neighbor (AkNN) method to raise alarms for faults. Through testing over real plant data, the framework assists process operators by providing in-depth operating information of the reactor and fault diagnosis.
关键词： pyrolysis reactor,thermal imaging,deep learning,smart monitoring system
更新于2025-09-10 09:29:36
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Thermography is cool: Defect detection using liquid nitrogen as a stimulus
摘要： This paper mainly explores cooling instead of heating for external stimulation in infrared thermography for NDT & E. Liquid nitrogen is sprinkled on the surface of a steel sample with flat-bottom holes and a thermal camera captures the whole process. Pulsed thermography and lock-in thermography are also employed to obtain a good comparison. In image processing procedure, the principal component thermography method is performed on all thermal images. Moreover, the corresponding receiver operating characteristic curves are established and discussed. A comparison of the results indicates that the liquid nitrogen technique could be considered as a valid option for NDT & E.
关键词： FFT,defects,experiment,thermography,thermal imaging
更新于2025-09-09 09:28:46
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Thermal management and characterization of high-power wide-bandgap semiconductor electronic and photonic devices in automotive applications
摘要： GaN-based high-power wide-bandgap semiconductor electronics and photonics have been considered as promising candidates to replace conventional devices for automotive applications due to high energy conversion efficiency, ruggedness, and superior transient performance. However, performance and reliability are detrimentally impacted by significant heat generation in the device active area. Therefore, thermal management plays a critical role in the development of GaN-based high-power electronic and photonic devices. This paper presents a comprehensive review of the thermal management strategies for GaN-based lateral power/RF transistors and light-emitting diodes (LEDs) reported by researchers in both industry and academia. The review is divided into three parts: (1) a survey of thermal metrology techniques, including infrared thermography, Raman thermometry, and thermoreflectance thermal imaging, that have been applied to study GaN electronics and photonics, (2) practical thermal management solutions for GaN power electronics, and (3) packaging techniques and cooling systems for GaN LEDs used in automotive lighting applications.
关键词： semiconductor,Raman thermometry,infrared thermography,high-power,automotive applications,LEDs,thermoreflectance thermal imaging,GaN,thermal management,wide-bandgap
更新于2025-09-04 15:30:14