Non-contact Nature Research Articles

Measurement of Nanometric Heights by Modal Decomposition

Measuring the height of steplike features in samples has become important in many scientific and industrial applications. It is routinely done using both tactile and optical methods, the latter being preferable due to their noncontact nature and improved speed capabilities. Nevertheless, techniques less sensitive to instabilities or without calibration or reference sample requirements would be advantageous. Here, we propose a method to measure nanometric step heights based on a modal analysis of the reflected or transmitted field. Our approach requires a minimum of four single-point measurements by detectors with no spatial resolution (photodiodes) and yet can reconstruct spatial structure with nanometric resolution. It has the benefits of not requiring a reference measurement or calibration and it is completely digital, thus offering high reliability and real-time measurement. As proof of principle, we perform measurements on reflective samples, finding excellent agreement between the set and measured values, with uncertainties comparable to those of scanning-force microscopes.

Employing vision-based sensing for long-term monitoring

Despite the crucial role of structural health monitoring (SHM), traditional contact-based sensors are costly and lacking automation. Vision-based sensors have recently emerged as a potential substitute, due to their non-contact nature and low cost. However, investigations lack validating their long-term performance. This study assesses vision-based sensing for robust and efficient long-term displacement monitoring. Additionally, the suitability of various machine learning (ML) algorithms in automatically extracting information from the generated data are examined. A first experiment examines the capability to monitor ambiently excited structures over long periods. The parameters assessed are: a) noise and drift (e.g., related to environmental changes such as temperature, humidity, and lighting); and b) obtainable displacement resolution related to ambient excitation. Then, a second experiment examines the capability to monitor dynamically excited structures over long periods (via the employment of an artificial excitation, e.g., an eccentrically loaded mass motor). Here, the following parameters assessed are the: a) frequency bandwidth range; b) frequency resolution; c) displacement resolution related to dynamic excitation; and d) maximum number monitored points for given computational resources. Finally, for processing the generated data, the following ML algorithms are examined: a) Artificial Neural Networks (ANNs); b) support vector machines (SVMs); c) decision trees; and d) Convolutional Neural Networks (CNNs). Concerning long-term monitoring, the paper found that non-contact sensing had comparable accuracy with traditional contact-based sensors. About the ML models, the CNNs were found to be advantageous. Whilst this study was carried out on a small-scale structure, the potential of vision-based sensing for long-term monitoring of full-scale structures was highlighted.

Laser cutting of carbon fiber reinforced plastic components for remanufacturing

Carbon fiber reinforced plastic (CFRP) is extensively used in automotive and aerospace industries with the aim to achieve reduction on emissions by reducing weight. Due to governmental regulations to reduce the environmental impact and to reduce waste, the need for remanufacturing CFRP is becoming an interesting area of application with economic benefits to industry. This is important as manufacturing carbon fiber is a costly process and remanufacturing CFRP is more cost effective and reduces the dependency on virgin materials. Processing CFRP to meet demands, for fast and high-quality cuts, can impose problems for conventional methods. The use of multi-pass scanning technique in laser cutting CFRP is investigated using a 1.5 kW fiber laser with assist gas pressure of 16 bar and gas flow rate of 126 lt/min. Using multi-pass technique, a through cut can be obtained by repeating the beam travel more than once. The advantage of laser cutting when compared with traditional CNC, is the low cost of maintenance over time due to the non-contact nature of the process i.e. no wear of tool at contact area. And due to the small beam spot size of the laser small and complex shapes can be cut. The aim of the paper is to determine how the process performs in terms of cutting speed and fiber damage. Average power was used to carried out experimental tests. A fiber damage below 100 µm with laser cutting speed of 2.5 m/min and above was obtained. Thermal effects were analyzed using scanning electron microscope (SEM) and optical microscope (OM). The fiber damage was further optimized using specialist methods such as double aperture nozzle and trenching. The use of trenching and double aperture further reduces the fiber damage to 10 µm and 50 µm, respectively with laser cutting speed of 7.5 m/min and 3.33 m/min.

Wettability tailored superhydrophobic and oil-infused slippery aluminium surface for improved anti-corrosion performance

Inspired by the non-contact nature offered by the superhydrophobic surfaces of living creatures in nature, the superhydrophobic and slippery liquid-infused porous surfaces (SLIPS) have been fabricated to meet the engineering problems including metal corrosion. In this research, we fabricate the hydrophobic, superhydrophobic, hydrophobic lubricant-infused surface (H-SLIPS), and superhydrophobic lubricant infused surface (SH-SLIPS) onto aluminium alloy surfaces and explored their anti-corrosion properties. The hydrophobic and superhydrophobic surfaces are fabricated by hot-water treatment and silicon oil grafting onto the plain and superhydrophilic surface created by hot water treatment of the chemically etched aluminium surface, respectively. The corresponding SLIPS are fabricated by infusion of the silicone oil onto the prepared hydrophobic and superhydrophobic surfaces. Although the superhydrophobic surface exhibits self-cleaning behavior, the SLIPS shows excellent self-healing properties. In addition, the H-SLIPS shows better lubricant layer stability compared to the SH-SLIPS. The corrosion resistive and electrochemical impedance studies illustrate that H-SLIPS surfaces exhibit excellent anti-corrosive properties as compared to other substrates and show long-term performance, even after 30 days. Thus, the study illustrates that H-SLIPS performs better and the infused oil stability is a critical factor for applications like anti-corrosion properties.

A Comparison of Video-based Methods for Neonatal Body Motion Detection.

Preterm infants in a neonatal intensive care unit (NICU) are continuously monitored for their vital signs, such as heart rate and oxygen saturation. Body motion patterns are documented intermittently by clinical observations. Changing motion patterns in preterm infants are associated with maturation and clinical events such as late-onset sepsis and seizures. However, continuous motion monitoring in the NICU setting is not yet performed. Video-based motion monitoring is a promising method due to its non-contact nature and therefore unobtrusiveness. This study aims to determine the feasibility of simple video-based methods for infant body motion detection. We investigated and compared four methods to detect the motion in videos of infants, using two datasets acquired with different types of cameras. The thermal dataset contains 32 hours of annotated videos from 13 infants in open beds. The RGB dataset contains 9 hours of annotated videos from 5 infants in incubators. The compared methods include background substruction (BS), sparse optical flow (SOF), dense optical flow (DOF), and oriented FAST and rotated BRIEF (ORB). The detection performance and computation time were evaluated by the area under receiver operating curves (AUC) and run time. We conducted experiments to detect motion and gross motion respectively. In the thermal dataset, the best performance of both experiments is achieved by BS with mean (standard deviation) AUCs of 0.86 (0.03) and 0.93 (0.03). In the RGB dataset, SOF outperforms the other methods in both experiments with AUCs of 0.82 (0.10) and 0.91 (0.05). All methods are efficient to be integrated into a camera system when using low-resolution thermal cameras.

Experimental study on forming consistent accuracy and tool electrode wear involved in fabricating array microelectrodes and array micro holes using electrical discharge machining

Despite the non-contact nature of electrical discharge machining (EDM) process makes it become one of most promising methods to fabricate array micro structures, the low consistent accuracy, serious tool wear and low prepared efficiency has hindered the development and applications of EDM technology in fabricating array micro structures. To fill this gap, the mixture feeding model was firstly introduced to fabricate array microelectrodes by low speed wire electrical discharge machining (LS- WEDM) to balance the contradiction between consistent accuracy and prepared efficiency. Firstly, the contrast experiments of preparing array microelectrodes with various feeding models were conducted, and results indicated that the processing efficiency of square array microelectrodes obtained by mixture model was increased by 36.4% compared to constant velocity model. Besides, the consistent accuracy, corner radius and taper accuracy of square array micro holes were investigated in detail. The effects of lifting model and lifting speed on surface roughness parameters of inner wall of square array micro holes were disclosed. Moreover, the transverse and longitudinal tool electrode wear of square array microelectrodes were qualitatively measured and analyzed, and the mechanism for tool electrode loss involved in preparation of array micro holes in Ni-base single crystal superalloy was revealed. The research results are of great significance for improving the prepared accuracy of array microelectrodes and promoting engineering application of EDM technology in preparing array micro structures.

Analysis of the associations between salivary cortisol-, alpha-amylase-, and testosterone-responsiveness with the physical contact nature of team handball: a preliminary analysis.

This study evaluated endocrine responsiveness (ER) to physical stress (contact vs. non-contact nature of play) during team handball matches, according to the playing positions, thereby contextualizing the contact nature of the handball match. The participants were ten male team handball players (24.1±3.17 years, 188.2±6.42 cm, 94.6±9.6 kg) divided into two groups: contact playing positions (CPP) and non-contact playing positions (NCPP). To evaluate the ER, the salivary cortisol (C), testosterone (T), and alpha-amylase (AA) concentrations were assessed before the game, during the halftime break, and after the match. Moreover, playing time (PT) and the number of contacts (NC) were counted post-match by video analysis. To determine possible differences between PT and the NC in the first and second halves of the match, a paired-sample t-test was used. The differences among ER-measures were calculated by the magnitude-based Cohen's effect size. Possible associations between NC and ER were analyzed by comparing CPP and NCPP in C, T, and AA. The CPP group performed significantly more physical contacts, while there was no difference in playing time between the groups. A stronger C response was evidenced in players with a longer playing time. During the game, the C response was directly determined by physical contact, with CPP players showing a stronger C response than NCPP players. This study provided evidence of the importance of contact actions during matches and training sessions, as a parameter of calculating training loads and preparing strategies for recovery and injury prevention. Further studies examining larger samples are warranted.

Technique Variation for MPFL Reconstruction in Skeletally Immature Patients: Data from the Jupiter Cohort

Background:Management approaches and surgical techniques, when applied for pediatric and adolescent patellofemoral instability (PFI), continue to lack clear clinical guidelines and indications. Medial patellofemoral ligament reconstruction (MFPLR) is among the most popular surgical options. However, variation in technique remains significant, particularly in skeletally immature sub-populations.Purpose:The purpose of this study was to examine the variation in MPFLR technique in skeletally immature patients within a cohort of 20 orthopedic surgeons with different experience levels and specialty training backgrounds. Methods: All operative records of skeletally immature patients from 2016 to 2021 were retrieved from the JUPITER cohort, a multi-center prospective study involving 13 different tertiary care academic centers. Patients who underwent a primary single-stage MPFLR were evaluated in this study. Demographic information and operative details were collected for each knee.Results:Of the 306 knees, 205 (53% female, 47% male) met inclusion criteria and comprised the final cohort (Table 1). The average age was 13.6 ± 1.8 yrs (5.1-19.0). The initial injury mechanism was of a non-contact nature in 73% and a result of contact in 17%. 47% of surgeons utilized autograft while 53% utilized allograft. Suture anchors (including small tenodesis screws) were the most popular patellar fixation technique (61%), followed by the use of tunnel under a bone bridge (37%). The majority of surgeons utilized 2 suture anchors (59%). Interference screws were the most popular femoral fixation technique (84%), followed by suture anchors (12%). The majority of surgeons used either 1 interference screw 97(%) or 1 suture anchor at the femur (96%). In addition to MPFLR, 15% of patients underwent osteochondral fracture treatment: 36% underwent loose body removal, while 61% underwent fixation. Lateral Retinacular Release was performed in 13% of cases, and lateral retinacular lengthening was performed in 2%. 10% of patients underwent concomitant hemi-epiphysiodesis for genu valgum, 3% underwent medial quadriceps tendon-femoral ligament reconstructions, and 3% underwent a Grammont realignment (patellar tendon medialization) procedure.Conclusion:Variation in different aspects of MPFLR technique is substantial among this cohort of orthopedic surgeons. Given the well-established importance of decreasing variation for healthcare cost containment and optimization of outcomes, comparative studies and sub-stratified analyses are needed to better elucidate the most favorable techniques and their components.Table 1.Demographic and Surgical Data

Comparison and Analysis of Different Thermography Techniques in the Biomedical Applications

Thermography is a technique that involves using a thermal camera to make a thermogram image that depicts the quantity of infrared energy emitted, transmitted, and reflected by an object. Body surface temperature monitoring, which varies when blood flow increases or decreases due to clinical irregularities, has been frequently utilised to diagnose medical problems such as breast cancer, diabetes neuropathy, and peripheral vascular disorders using thermography. Thermography has become a significant tool, particularly for fever screening during infectious disease epidemics such as Ebola and COVID-19, due to its non-invasive and non-contact nature. Thermography is a sensory instrument that can be particularly valuable in protecting human health when paired with thermal physiology data. In this review, we analyze and compare several thermography processes and aspects to come up with the optimal methodology for use in the medical field.

Exploring Factors of Preschool Parents’ Behavioral Intention to Use Face Recognition Technology on Campus

Face recognition technology (FRT) is being increasingly used to record the trajectory of human behavior due to its non-contact nature and high accuracy. When the technology is extended to education, it is applied to manage students’ access to campus, to analyze learning behaviors, and to monitor students’ campus activities. It is important to note that the use of face recognition technology for students on campus should be approved by the students’ guardians. Therefore, this study aimed to determine what factors affect the behavioral intentions of preschool parents’ adoption of facial recognition systems on campus. Unlike previous studies, the model of this study was designed to focus not only on the affective dimension, but also on the parenting style. The model was validated with data from an online questionnaire completed by 419 preschool parents. AMOS was used to analyze various assumptions of the model. The analysis revealed that innate consumer innovativeness positively influenced experience values and helicopter parenting which directly affected their behavioral intentions. The results imply that in the application of face recognition technology, parents’ behavioral intentions depend not only on the prior experiential value of the product and helicopter parenting, but also on parents’ innate consumer innovativeness. Therefore, for campus management and technology application, this study is useful to understand the behavioral intention of guardians to use the new technology. For operators and users of face recognition technology, this study provides several guidelines for exploring parental attitudes toward child supervision and improving products and services to value information security.

Development of an Electromagnetic Micromanipulator Levitation System for Metal Additive Manufacturing Applications.

Magnetism and magnetic levitation has found significant interest within the field of micromanipulation of objects. Additive manufacturing (AM), which is the computer-controlled process for creating 3D objects through the deposition of materials, has also been relevant within the academic environment. Despite the research conducted individually within the two fields, there has been minimal overlapping research. The non-contact nature of magnetic micromanipulator levitation systems makes it a prime candidate within AM environments. The feasibility of integrating magnetic micromanipulator levitation system, which includes two concentric coils embedded within a high permeability material and carrying currents in opposite directions, for additive manufacturing applications is presented in this article. The working principle, the optimization and relevant design decisions pertaining to the micromanipulator levitation system are discussed. The optimized dimensions of the system allow for 920 turns in the inner coil and 800 turns in the outer coil resulting in a : ratio of 1.15. Use of principles of free levitation, which is production of levitation and restoration forces with the coils, to levitate non-magnetic conductive materials with compatibility and applications within the AM environment are discussed. The Magnetomotive Force (MMF) ratio of the coils are adjusted by incorporation of an resistor in parallel to the outer coil to facilitate sufficient levitation forces in the axial axis while producing satisfactory restoration forces in the lateral axes resulting in the levitation of an aluminum disc with a levitation height of 4.5 mm. An additional payload of up to 15.2 g (59% of mass of levitated disc) was added to a levitated aluminum disk of 26 g showing the system capability coping with payload variations, which is crucial in AM process to gradually deploy masses. The final envisioned system is expected to have positional stability within the tolerance range of a few μm. The system performance is verified through the use of simulations (ANSYS Maxwell) and experimental analyses. A novel method of using the ratio of conductivity () of the material to density () of the material to determine the compatibility of the levitation ability of non-magnetic materials with magnetic levitation application is also formulated. The key advantage of this method is that it does not rely on experimental analyses to determine the levitation ability of materials.

Microfluidic Determination of Distinct Membrane Transport Properties between Lung Adenocarcinoma Cells CL1-0 and CL1-5.

The cell membrane permeability of a cell type to water (Lp) and cryoprotective agents (Ps), is the key factor that determines the optimal cooling and mass transportation during cryopreservation. The human lung adenocarcinoma cell line, CL1, has been widely used to study the invasive capabilities or drug resistance of lung cancer cells. Therefore, providing accurate databases of the mass transport properties of this specific cell line can be crucial for facilitating either flexible and optimal preservation, or supply. In this study, utilizing our previously proposed noncontact-based micro-vortex system, we focused on comparing the permeability phenomenon between CL1-0 and its more invasive subline, CL1-5, under several different ambient temperatures. Through the assay procedure, the cells of favor were virtually trapped in a hydrodynamic circulation to provide direct inspection using a high-speed camera, and the images were then processed to achieve the observation of a cell’s volume change with respect to time, and in turn, the permeability. Based on the noncontact nature of our system, we were able to manifest more accurate results than their contact-based counterparts, excluding errors involved in estimating the cell geometry. As the results in this experiment showed, the transport phenomena in the CL1-0 and CL1-5 cell lines are mainly composed of simple diffusion through the lipid bilayer, except for the case where CL1-5 were suspended in the cryoprotective agent (CPA) solution, which also demonstrated higher Ps values. The deviated behavior of CL1-5 might be a consequence of the altered expression of aquaporins and the coupling of a cryoprotective agent and water, and has given a vision on possible studies over these properties, and their potential relationship to invasiveness and metastatic stability of the CL1 cell line.

Process-Recipe Development for Printing of Multilayer Circuitry With Z-Axis Interconnects Using Aerosol-Jet Printed Dielectric Vias

Abstract Flexible electronics is emerging as a new consumer-industry phenomenon. The promise of additively printed flexible electronics has sparked interest in a detailed understanding of the parameters and interactions of the printing process with the realized performance. Aerosol Jet printing technology has garnered increased interest, owing to a noncontact nature of print process and the high standoff allowing for printing on nonplanar surfaces. Prior efforts with aerosol-jet printing have focused on single-layer substrates. The current efforts focus on higher end printed circuit boards designs, which may need multilayers, with multilayer stacking of interconnections and z-axis connections through vias. The results presented in the paper attempt to address the need for process recipes for multilayer circuits and z-axis interconnects. Aerosol printing method has been shown to have wide compatibility with wide array of inks such as silver, copper, and carbon. Realization of high-volume scale-up of the process needs process recipes with statistical assessment of process stability and variance. In this paper, z-axis interconnects have been realized with the help of Aerosol printable silver ink and dielectric polyimide ink. The interaction of the sintering profile and the realized conductivity and shear load value of the printed conductive metal layers has been presented for each of the additional layers. Additive build-up processes may need successive exposure to temperature for the purpose of sintering. The downstream-printed conductive lines would undergo different sintering conditions and would then be tested for parameters such as interconnect resistance and shear load to failure. This paper explores the printing of multilayer up to eight conductive layers. Sintering profile for lower resistance per unit length and higher shear load to failure was tested.

Thermal behaviour assessment and electrical characterisation of a cylindrical Lithium-ion battery using infrared thermography

This paper presents an experimental evaluation of the thermal and electrical performance of a commercial 26650 cylindrical LiFePO 4 battery cell. The thermal management of lithium-ion batteries is a key problem for electric mobility applications, where batteries are subjected to severe operating conditions. Accordingly, this study aims to demonstrate the reliability of infrared thermography in the quantitative analysis of heat generation in battery cells. In our opinion, infrared thermography can be very attractive owing to: (i) the non-contact nature of this technique and (ii) its capability to quickly scan measurement areas. Consequently, infrared thermography and thermocouple probe results were compared, providing evidence of similar behaviour. Moreover, we present an electrical characterisation of our lithium-ion battery. In particular, the cell potential, open circuit potential, and entropic heat coefficient vis-à-vis the state of charge were experimentally measured. The obtained experimental data were used to evaluate a simplified heat generation term that is widely employed in numerical approaches. The different contributions to heat generation were carefully analysed. The results show that the reversible term considerably influences the total thermal power. Moreover, infrared-based heat generation estimation can be considered reliable. • Thermal behaviour of Li-ion battery was experimentally analysed using IR thermography and thermocouples. • Experimental data were used to evaluate the battery heat generation using a simplified equation. • IR thermography can be used to quantitative evaluate battery heat generation.

AS-OCT and Ocular Hygrometer as Innovative Tools in Dry Eye Disease Diagnosis

Dry eye disease (DED) is one of the conditions that most commonly leads patients to visit an ophthalmologist. Fast and accurate diagnosis relieves patient discomfort and spares them from long-term effects on the ocular surface. Many tests used in the diagnosis of DED may be considered subjective as they rely on an experienced observer for image interpretation, resulting in variations in diagnosis. On one hand, the non-contact nature of the anterior segment optical coherence tomography (AS-OCT) device and its rapid image acquisition enable the measurement of the tear meniscus parameter without reflex tearing. On the other hand, an ocular hygrometer allows a rapid, safe, but also efficient, analysis and is associated with low costs and the repeatability of the procedure.

Swarm Robots Cooperative and Persistent Distribution Modeling and Optimization Based on the Smart Community Logistics Service Framework

The high efficiency, flexibility, and low cost of robots provide huge opportunities for the application and development of intelligent logistics. Especially during the COVID-19 pandemic, the non-contact nature of robots effectively helped with preventing the spread of the epidemic. Task allocation and path planning according to actual problems is one of the most important problems faced by robots in intelligent logistics. In the distribution, the robots have the fundamental characteristics of battery capacity limitation, limited load capacity, and load affecting transportation capacity. So, a smart community logistics service framework is proposed based on control system, automatic replenishment platform, network communication method, and coordinated distribution optimization technology, and a Mixed Integer Linear Programming (MILP) model is developed for the collaborative and persistent delivery of a multiple-depot vehicle routing problem with time window (MDVRPTW) of swarm robots. In order to solve this problem, a hybrid algorithm of genetically improved set-based particle swarm optimization (S-GAIPSO) is designed and tested with numerical cases. Experimental results show that, Compared to CPLEX, S-GAIPSO has achieved gaps of 0.157%, 1.097%, and 2.077% on average, respectively, when there are 5, 10, and 20 tasks. S-GAIPSO can obtain the optimal or near-optimal solution in less than 0.35 s, and the required CPU time slowly increases as the scale increases. Thus, it provides utility for real-time use by handling a large-scale problem in a short time.

Structural and oxide-based colours on laser textured copper

Laser texturing to create colours has recently attracted significant interest due to the rapid and non-contact nature of the technique. The complex optical response of femtosecond laser-textured copper surfaces, producing a palette of perceived colours with varying amounts of angle dependence, is presented. The colours depend on the line spacing used in the laser raster-scanning process. Grazing angle Fourier transform Infrared spectroscopy (FTIR) and Raman microscopy show increased oxide content with larger total accumulated fluence and increased pulse overlap. The increased oxide content coincides with a greater angle independence of the colours compared to colours obtained at larger line spacings. All samples have a similar sinusoidal periodic microstructure, with amplitudes ranging from 400 nm for the smallest line spacings (∼1 µm) to 100 nm for the largest line spacings (∼20 µm), and are decorated with nanoparticles. The angle dependence of the colours is quantified using reflectance measurements, which show a shift in reflectance peak with observation angle. The overall complex colour of the surfaces is attributed to a combination of copper oxides and structural colours driven by underlying nanoparticles, be they metal or metal-oxide, and sinusoidal gratings with a pitch of approximately 1 µm.

Optimization of laser cutting quality characteristics for basalt –glass hybrid composite using hybrid approach

In this research work, hybrid composite with combination of basalt fiber and glass fiber have been fabricated by the hand lay composite manufacturing technique. Moreover, its mechanical testing have been conducted. It has been perceived that fabricated hybrid composite has superior mechanical testing results. Precise machining of these composites is a tedious task. There are various limitations in conventional machining such as: fiber pullout, delamination, burr formation, crack formation in matrix etc., which can cause for poor machined surface and it also reduce mechanical performance of the hybrid composite. Laser machining can be one of the best alternative because of its non-contact nature with high production rate. In the present study, Artificial Neural Network (ANN) merged with genetic algorithm (GA) hybrid technique has been used to investigate the effects of machining parameters on responses.

55 Years of Holographic Non-Destructive Testing and Experimental Stress Analysis: Is there still Progress to be expected?

Holographic methods for non-destructive testing, shape measurement, and experimental stress analysis have shown to be versatile tools for the solution of many inspection problems. Their main advantages are the non-contact nature, the non-destructive and areal working principle, the fast response, high sensitivity, resolution and precision. In contrast to conventional optical techniques such as classical interferometry, the holographic principle of wavefront storage and reconstruction makes it possible to investigate objects with rough surfaces. Consequently, the response of various classes of products on operational or artificial load can be examined very elegantly. The paper looks back to the history of holographic metrology, honors the inventors of the main principles, discusses criteria for the selection of a proper inspection method, and shows exemplary applications. However, the main focus is on modern developments that are inspired by the rapid technological process in sensing technology and digitization, on current applications and future challenges.

Human Stress Recognition from Facial Thermal-Based Signature: A Literature Survey

Stress is a normal reaction of the human organism which triggered in situations that require a certain level of activation. This reaction has both positive and negative effects on everyone’s life. Therefore, stress management is of vital importance in maintaining the psychological balance of a person. Thermal-based imaging technique is becoming popular among researchers due to its non-contact conductive nature. Moreover, thermal-based imaging has shown promising results in detecting stress in a non-contact and non-invasive manner. Compared to other non-contact stress detection methods such as pupil dilation, keystroke behavior, social media interaction and voice modulation, thermal-based imaging provides better features with clear boundaries and requires no heavy methodology. This paper presented a brief review of previous work on thermal imaging related stress detection in humans. This paper also presented the stages of stress detection based on thermal face signatures such as dataset type, thermal image face detection, feature descriptors and classification performance comparisons are presented. This paper can help future researchers to understand stress detection based on thermal imaging by presenting the popular methods previous researchers use for stress detection based on thermal images.