The exposure to extreme temperatures in workplaces involves physical hazards for workers. A poorly acclimated worker may have lower performance and vigilance and therefore may be more exposed to accidents and injuries. Due to the incompatibility of the existing standards implemented in some workplaces and the lack of thermoregulation in many types of protective equipment that are commonly fabricated using various types of polymeric materials, thermal stress remains one of the most frequent physical hazards in many work sectors. However, many of these problems can be overcome with the use of smart textile technologies that enable intelligent thermoregulation in personal protective equipment. Being based on conductive and functional polymeric materials, smart textiles can detect many external stimuli and react to them. Interconnected sensors and actuators that interact and react to existing risks can provide the wearer with increased safety, protection, and comfort. Thus, the skills of smart protective equipment can contribute to the reduction of errors and the number and severity of accidents in the workplace and thus promote improved performance, efficiency, and productivity. This review provides an overview and opinions of authors on the current state of knowledge on these types of technologies by reviewing and discussing the state of the art of commercially available systems and the advances made in previous research works. Thermal stress is among the most common physical hazards in various work sectors. In fact, any worker exposed to a high heat load through a combination of his or her metabolic heat during work, environmental factors , and the clothing requirements of his or her job can suffer health problems . In addiIndeed, the exposure to extreme temperatures can lead the worker to a state of heat stress, which occurs when the body is unable to maintain its temperature between 36 and 37 °C . TherefoIn addition to being a direct cause of serious injuries in the workplace, thermal stress can indirectly lead to accidents and other types of injuries. A poorly acclimated worker may have reduced performance and alertness and therefore may be at greater risk of accidents and injuries ,7,8. OneExposure to extreme temperatures can also temporarily reduce work capacity and affect productivity . As a reThe protection of workers against thermal risks becomes even more important since, according to experts, the current climate change context will contribute to emphasizing the impact of thermal constraints in the workplace ,16,17. OAs a result of the importance of preventing the risks of thermal stress, recommendations and measures have been planned by the authorities. These regulations recommend redesigning the workstation, reducing the workload, and wearing appropriate personal protective equipment (PPE) to ensure that thermal stress thresholds are not exceeded. However, some studies have shown that despite compliance with these regulations, some workers may be subject to thermophysiological constraints depending on their age, sex, physical fitness, or state of health . Moreove®), high-performance polyethylene (HPPE)), coated or not with polymers, in single or multiple layers [®), para-aramide (Kevlar®), polybenzimidazole (PBI), melamine (Basofil®), polyphenylene benzobisoxazole (Zylon®), and polyimide for heat and flame hazard, polyurethane (PU), chlorinated polyethylene (CPE), polytetrafluoroethylene (PTFE), PVC, and polyvinylidene chloride (PVDC) as impermeable layers and moisture barriers [In addition to several gaps in the established regulations to counter the risks of thermal stress in the workplace, PPE can accentuate the impact of thermal stress, as many of these items of equipment lack comfort . PPE is e layers ,25,26,27barriers , or actibarriers ,29,30,31barriers ,26,32,33barriers ,35.However, the materials used in the design of several types of PPE tend to avoid the adequate dissipation of body heat . Thus, wGiven the existing shortcomings in the prevention of thermal stress in workplaces due to conventional conception in the design of protective equipment and the inefficiency of the established standards and recommendations, it is essential to develop new tools and equipment to ensure thermal risk management adapted to the individual situation of the worker and his or her work environment. In such a context, smart textile technologies integrated into personal protective equipment have a very great potential to respond to many issues related to thermal risks. Thus, using them in the development of PPE presents great potential for the field of occupational health and safety ,39,40,41Being based on textronic (e-textiles), conductive textiles, functional textiles, and flexible and extensible electronics, smart textiles can contribute to the development of thermal regulation systems ,43 to beRecent technical reviews often report on knowledge in the area of smart textiles ,45,47, iIn spite of the recent technological progress, a preliminary analysis has shown that most of the current commercial solutions are dedicated to the fields of sport and leisure, and very few are related to occupational protective equipment ,53. IndeWhile some integrated systems have presented risks of overheating , others Using the potential of advanced materials both in the design of conductive textiles and in the development of thermal sensors and actuators to be integrated in protective equipment can provide a reliable solution to fill current lacks in the design of intelligent thermal management tools in the context of occupational health and safety. Therefore, the present study aims to present a review of current knowledge of these technologies facilitating smart thermoregulation in personal protective equipment.This part of the study focuses on systems that provide data on the body temperature of an active person. It also discusses the sensors that can be integrated into PPE in order to facilitate the acquisition of the temperature of the microclimate under the clothing or the outside temperature with the objective of warning the worker in case of prolonged exposure to extreme temperatures.c) and the skin temperature (Ts). While Tc is adjusted by thermoregulatory mechanisms of the body, Ts is affected by blood circulation and is related to heart rate (HR) and metabolic rate [s and Tc) must operate efficiently over a temperature range of 35 to 40 °C and ideally offer a measurement accuracy of 0.1 °C [Real-time monitoring of body temperature is very important in order to prevent in time the occurrence of disorder in many organs during exposure to high thermal stress . The callic rate . Therefof 0.1 °C .s and Tc). These sensors are generally based on thermistors, resistance temperature detectors (RTDs) [Various types of analog electrical sensors have been deployed in recent years to measure body temperature (Ts (RTDs)     in a knitted structure , by inteSome studies, on the other hand, have reported an optical sensing approach for measuring body temperature by integrating optical fibers into the textile structure . As a reAlthough these studies are still at a very preliminary stage, some research groups have attempted to develop shape memory textile sensors. The concept is based on the use of shape memory polymers sensitive to external stimuli such as light or temperature. Recently, the innovation of sol gels, conductive polymers, and copolymers as biomaterials enabled the miniaturization of biological analyses in an integrated chip with new generation sensors using a Si light source with a wide visible wavelength range as an optical biosensor .Temperature sensing functionality can be obtained by spinning shape memory polymer fibers, such as polyurethane fibers, with other types of fibers to make textile fabrics, or by coating shape memory polymer emulsions on a woven or knitted fabric . Other cMany researchers have also worked on the development of flexible temperature sensors with the deposition of materials that facilitate temperature detection on flexible polymeric substrates using printing, coating, and lamination techniques  Figure .If they maintain their mechanical strength, these types of sensors can then be attached to fabrics or integrated into textile structures . In thisPrinting techniques were also used to design flexible temperature sensors . The mos3O4) on a solid substrate [The formation of composite layers on flexible substrates has also been another method for the design of flexible temperature sensors. In this register, a composite film with RTD properties could be obtained by coating a mixture of poly o-methylaniline and manganese oxide  RFID tag, which is based on the temperature dependence of the ring oscillator frequency and allows data to be sent to a reader at 868 MHz with a range of 2 m [s and must allow the natural perspiration of the skin to be preserved [As part of the development of flexible temperature sensors, other work has opted for radio-frequency identification (RFID) tags to be placed on the skin to measure Te of 2 m . Similare of 2 m . Accordireserved . In a sireserved . In addireserved .Advanced materials have also been applied to the optimization of certain types of portable devices such as portable in-ear devices, which is a new technological trend in recent years to measure body temperature and other physiological parameters through sensors that hold. A dispersion based on graphene, as a highly conductive material known for its strong optical absorption in the infrared range, has been coated on the silicon substrate of the lens of IR thermopiles used in portable in-ear devices with the aim of increasing the accuracy of measurements in such a thermopile .s at the wrist [The overall analysis of the research on temperature sensors integrated in textile structures, textile sensors, and flexible temperature sensors has shown that the vast majority of these studies remain at the level of proof-of-concept of components that are still to be integrated in clothing, although some work is dedicated to temperature sensors integrated in work clothing. In one of these studies, the ambient temperature and heat flux through the garment could be measured by a modified PTC grade sensor network integrated in the outer and inner side of the firefighters’ protective clothing with the transmission of the collected data to an external reader device using the Zigbee communication protocol. The prototype, tested on a thermal manikin in the laboratory, had yet to be validated in an operational environment . A work he wrist . This jahe wrist .s were developed to assess the conditions of soldiers in real time. Both were tested on about 40 subjects, but the assembly remained cumbersome, and the main signal transmission lines were fabricated with electrical wires that could be damaged during use or maintenance [s [A smart glove and an armband each comprising two electrodes made of conductive textiles to measure the galvanic skin response and a sensor from a commercial digital thermometer detecting Tntenance . A thermntenance ,82 has bnance [s . The cufnance [s .s from the chest.Due to the need to monitor patient health or athlete performance, more and more portable products with temperature sensors have appeared on the market in recent years. Some integrate temperature sensors into their structure and others are based on the deployment of advanced materials. Among the commercial devices for biometric sign detection in the form of portable accessories in recent years, Biofusion  and QardioCore  offer integrated systems that use contact RTD-type temperature sensors to measure TBased on printable electronics techniques, flexible temperature sensors have also been produced and have entered the market to serve areas such as transportation, logistics, food supply chain, and home appliances. Thanks to their flexibility, their integration into textile structures seems conceivable. However, their adaptation to textile structures still requires a certain number of technical challenges to be taken up, especially in terms of durability in wear or maintenance, especially in washing . These tThen, circuits containing these types of printed thermistors can be combined in a hybrid system with wireless data transmission protocols . AccordiRegarding products marketed in the form of temperature sensors integrated into clothing, a very limited number of products exist on the market. These products were mainly developed to help protect firefighters . In thisThe Balsan fire jacket  was also equipped with temperature and humidity sensors. A temperature sensor on the outside of the jacket measures the environmental temperature and a pair of temperature/humidity sensors on the inside of the jacket measures microclimatic conditions close to the body. When parameters exceed a certain level, an audible and visual alarm alerts the firefighter ,141.The review of research literature for measuring body temperature tools and sensors that can be integrated into protective equipment to assess the microclimate under the clothing or the environmental temperature in order to develop warnings in case of very high thermal stress are presented in Concerning the studies dedicated to temperature sensors that can be integrated in textiles, the present state of the art has found that a lot of work is dedicated to the design of temperature sensors based on smart textiles and flexible electronics ,93,157, In addition, experts in flexible electronics have shown great interest in the development of temperature sensors on flexible polymeric substrates. Graphene layers deposited on flexible substrates have demonstrated RTD properties of very high temperature sensitivity. However, in an extensible configuration, the RTD graphene layers have shown thermal properties sensitive to mechanical deformations. Layers with RTD properties have also been developed on flexible substrates by depositing different types of dispersion  using printing techniques. These heat-sensitive printed layers were able to ensure high temperature sensitivity while demonstrating low hysteresis in the heat–cooling cycles. The formation of composite layers on flexible substrates also allowed the fabrication of flexible temperature sensors. Among the various developments, composite layers based on carbon nanotubes have made it possible to obtain thermal sensitivities comparable to those of metals. However, in many studies on composite layers, electrodes based on precious metals such as gold have been used. Despite the advantages of some concepts for flexible temperature sensors, significant efforts are required to integrate them into clothing. From a general point of view, work on textile-integrated temperature sensors, textile sensors, and flexible temperature sensors seems to remain at the level of proof of concept with very few connected device demonstrators and even fewer prototypes of garments equipped with temperature sensors. In addition, the influence of various environmental parameters on the performance of these types of sensors remains unknown. Among the few studies on the design of garments with integrated temperature sensors, very few were dedicated to protective equipment, and almost all the work was carried out in the laboratory with tests on very few subjects. The effectiveness of these concepts has yet to be validated in operational environments. In addition, in most of these studies, conventional electrical wires were used for electrical connections or to ensure the transmission of collected signals. These types of structures containing electronics can be vulnerable to mechanical constraints during use and maintenance. The use of structures based on conductive textiles is to be expected in order to ensure a better mechanical resistance in use. Clothing equipped with temperature sensors that incorporate rigid thermistors embedded in textile fibers also require optimization efforts in order to reduce the impact of mechanical stresses on the quality of the sensor reading. The literature also mentions the influence of the fibrous structure surrounding the sensor on the reading . Not onlAmong the commercially available products, flexible temperature sensors seem to be able to ensure high measurement accuracy and very short response times. Being mainly based on a very thin printed structure, this type of sensor requires relatively low power supplies of the order of microwatts. These products, which are currently manufactured on flexible polymeric substrates, are mainly dedicated to the fields of warehousing and logistics. In order to extend their application to clothing, research is still needed to ensure their reliability and durability in use. Very few products including garments with integrated temperature sensors currently exist on the market. These products are mainly dedicated to the protection of firefighting workers. These types of protective equipment, which include temperature sensors incorporated into their structure, can warn the firefighter when predefined temperature thresholds inside or outside the garment are exceeded. In recent years, the textile industry has proposed multiple solutions to offer better protection against the cold during outdoor winter activities. The use of various types of textile materials has made it possible to reduce heat loss from the body while ensuring the transmission of moisture from sweat through a garment that must remain water and wind resistant .Despite technological advances in textile materials engineering, these types of garments still need to be improved. Indeed, most garments against extreme cold remain bulky by being based on multilayer fibrous structures taking advantage of the thermal resistance of textile materials, which depends mainly on their content of air trapped inside. In addition, highly insulating garments can sometimes limit body and arm movement and reduce manual dexterity, thus affecting individual performance. A feeling of discomfort may be particularly accentuated when clothing against the cold is worn in combination with other clothing ,159. In During intense activities in the cold, excessive perspiration, and consequently the humidification of the inner layers of the garment, can lead to a considerable decrease in thermal insulation, thus increasing the risk of cold-related injuries ,161. To Among the different categories of personal heat garments, this study has mainly focused on electric heat garments, as they can provide heat in a sustained and durable manner throughout the performance of tasks in extreme cold, depending on the endurance of their portable power source. In addition, their structure incorporating a heating element could provide heat distribution in a space-saving, thinner cold protective garment ,163. TheIn contrast to electric heating garments, fluid-flow-based heating garments are very bulky. Almost every example of this type of heating garment, based on a flexible tubing system for circulating liquid or hot air, requires an external energy source and fluid supply. In addition, the tubing system integrated into the garment makes it rigid, which may limit its usability during activities . NeverthHeating garments based on phase change material (PCM) also have important limitations despite a very interesting potential and many dedicated efforts. The most important limitation of this technology is its temporary heating effect. Although it is active during its phase change period, the release of heat ceases when the PCM, initially in a liquid state, solidifies with exposure to cold. Thus, in order to recover its heat source based on a phase change mechanism, it is necessary for the PCM to move away from the cold environment to reach its liquid state again . It has Since the thermal regulation capacity of textiles incorporating PCM is highly dependent on the amount of material deployed, the incorporation of PCM pockets in clothing generally leads to heavy clothing and may only be suitable for people for whom, depending on the activities, the extra weight is not a problem . To addrChemical heating garments are mainly based on chemical energy converted into thermal energy by oxidation during the reaction of chemical substances and are mostly used in diving suits to protect divers in cold water. The integration method remains primitive, because the reactive material placed in cushion-like packages is glued by an adhesive to the inner surface of the garment. The heat-generating chemicals are kept in separate compartments inside the cushion. When the user presses the pad, the barrier between the substance’s breaks, and the reagent mixes is generating heat. Although this system can use a mass of selected reagents to provide a highly exothermic chemical reaction free of gaseous by-products, the released temperature is difficult to control and of limited duration ,167.Despite durable heating throughout the duration of cold work, the low capacity of the batteries to ensure the proper functioning of the integrated heating system during long exposures to cold remains one of the major drawbacks of textile structures incorporating electric heating elements . The rapThe functioning of electric heating garments is based on the Joule heating principle also known as ohmic heating , accordiIn order to circumvent these drawbacks, the design of heating elements based on conductive textile fibers or the deposition of conductive layers on the surface of textiles has been proposed by the scientific community . Based oTM fibers (a type of aromatic polyester) [With the goal of solving the problems associated with the use of electrical wires as an integrated heating element in clothing, several works have attempted to apply metallic textile wires or wires made from metallic compositions . In partlyester)  were sewlyester) . Based olyester) , a protolyester) . Accordilyester) . Using tlyester) . In addilyester) . All theAs knitted fabrics offer flexible and stretchable structures, the creation of knitted heating elements has attracted particular attention from the scientific community in recent years ,181,182.Analysis of the design of weft knitted heating pads using three different types of conductive textile yarns embedded in two knitted fabrics of similar structure, but with different main yarns (acrylic and polyester respectively), showed that the electrical resistance of the conductive yarn and the composition of the knitted textile fibers surrounding the conductive textile yarn greatly influence the heat generated at a fixed supply voltage. The authors concluded that the acrylic yarn of the knitted fabric would have better heating and heat retention properties compared to polyester when using the same type of conductive yarn . The infIn addition to silver or silver-coated conductive textile yarns, other types of conductive textile yarns with a metallic composition were also considered for the design of heating elements. The study of the behavior of steel wire-based heating panels using single and multilayer steel wire integrated in clothes showed that the thermal effect obtained, and the time required to reach an equilibrium temperature at a fixed voltage, depended on the number of wire folds in the cloths . In addiIn this context, a fabric with variable insulation properties was developed with a structure consisting of three fleece layers and two interlayers comprising copper filament spirals and Nitinol as a temperature-sensitive shape memory element. The inner layers, being heated by the passage of an electric stream, made it possible to increase the thickness of this part of the fabric during the heating process, thus ensuring the increase in the insulation of the fabric due to the increase in air present in the transverse direction of the fabric. The heat-induced physical change in the conductive spirals could be electrically adjusted, providing a means to control the overall insulation level of the fabric . FinallyTo facilitate the design of electric heating elements based on metallic textile wires, some research work has proposed mathematical models to better anticipate the behavior of the heating textile to be developed. In one of these studies, the thermomechanical properties of knitted structures based on silver-coated textile yarn were mathematically modeled as a function of the influence of the contact pressure at the structural bonding points on the heating level. Thus, considering the relationship of the electrothermal property of the material and the structural parameters of the knitted fabric, the resulting temperature and loop resistance of a knitted fabric of uniform width can be predicted. Practical validation of the model with a heated knitted fabric based on silver-coated polymeric yarn showed that the maximum temperature obtained at a fixed supply voltage would depend on the structure of the knitted fabric in plain, ribbed, and interlock stitches . The samAnother theoretical model has been proposed to control the temperature of conductive knitwear of various courses and stitch yarns based on the quantitative relationship between the electrical resistance of a conductive knitwear and the temperature provided. According to this model, by knowing the initial resistance and thermal diffusivity  of the kThese types of patterns have also been proposed to predict the design of heated woven fabrics. In order to express the relationship between various parameters of a heated woven fabric, an equation was proposed based on the resistance of the fabric, the heat output power, the DC voltage, the number of parallel conducting wires, the length of the single conducting wire, the resistivity of the conducting wire, and the cross-sectional area of the conducting wire. Validation experiments using the integration of silver filaments and silver-coated yarns in identical cotton fabrics concluded that the conductive yarns or filaments must be uniformly distributed in order to avoid overheating on parts of the heating fabric . It was According to some of the models discussed, knowing the electrical resistance of a conductive tissue can greatly contribute to predicting its electrothermal behavior ,195. The2. Despite such performance, due to the relatively low environmental stability of silver nanofilaments, the developed heating fabrics lost their performance after two months of storage under ambient conditions. In addition, the created conductive layer was damaged during washing, and its thermal performance was significantly reduced [In order to facilitate the design of a heating element in a textile with a versatile design, and to overcome the technical challenges related to the integration of a conductive wire in a textile structure, coating techniques have been deployed to form conductive and heating zones on the surface of textile substrates. The deposition of a silver particle-based conductive ink on the surface of one polyester/cotton fabric resulted in a heating element that provided a maximum temperature of 33 °C with power supplies as low as 1.4 Watt and a time of about 10 s to reach the equilibrium heating temperature . In a si reduced . In orde reduced  should bThe formation of polymeric conductive layers on textile substrates has also been explored for the design of electrical heating textiles. The in situ polymerization of poly  p-toluene sulfonic acid (PEDOT-PTSA) on a polyester web by coating has allowed the development of a very flexible and lightweight heating textile with a durable and high heating potential that still required high supply voltages . The depCarbon fibers are also very interesting candidates in the design of electric heating textiles because of their good thermal efficiency and ability to generate uniform heat quickly ,207. AllA few studies have also been devoted to the use of carbon fiber-based heating elements in the design of electric heating garments. The evaluation of an electric heating vest with a carbon fiber-based heating element on a thermal manikin in a cold climate chamber has shown that the application of too high temperatures can lead to a reduction in heating efficiency due to a significant loss of heat to the environment, thus demonstrating that the heating power should be adjusted according to the external temperature . The infIn parallel with the numerous studies dedicated to the development of textile electric heating elements, some work has also been devoted to the evaluation of the efficiency of electric heating garments. The evaluation of a heated sleeping bag incorporating heating fabrics in the foot area on a thermal manikin, and subsequently on eight human subjects in the controlled conditions of a climatic chamber, has demonstrated the capacity of such a concept to keep feet and toes warm throughout the test period . The opts of the fingers was examined by recording the thermal sensation of human subjects wearing the gloves in a climatic chamber. The results showed that such a glove would maintain the temperature of the back of the hand and fingers within a comfort zone. The tests showed that in addition to improved thermal sensation and comfort in the fingers, the thermal sensation and whole-body comfort sensation increased slightly with the use of electrically heated gloves in cold weather.In order to offer more comfort and ease in the execution of tasks during activities in the cold, clothing allowing control or self-regulation of the temperature has also been studied. In this context, a vest with temperature control capability was developed by combining steel wire-based heating panels, in several configurations from one to four layers, with a digital temperature sensor and a microcontroller. These components, being worn on a carrier, were subsequently attached by means of Velcro strips under a multilayer cotton/polyester/polyamide garment. A user interface on an external handheld device was also used to control and display the temperature. In a self-regulating temperature mode, the heating circuit was activated by the microcontroller if the value measured by the temperature sensor fell below a preset value . Evaluats feedback using thermistors placed at various locations on the skin and a control system based on a microcontroller; and (3) the self-regulating but user-controllable garment with control of the thermistor feedback to maintain the internal temperature of the garment at a desired level and the use of an additional potentiometer to allow the user to control the set value of each actuator. According to the analyses of this study, total temperature self-regulation may be inadequate in complex thermal environments, indicating the need to consider ambient and body thermal effects in the thermal management of the temperature self-regulating system. By placing control of the system in the hands of the wearer, the self-regulating garment could overcome some of the challenges associated with complex environments by relying on the thermal sensation of the wearer [By applying a power switching method based on the self-monitoring of the heating element temperature, a heating textile with the ability to quickly reach various temperature levels, having a uniform temperature distribution band and ensuring the maintenance of the defined temperature, was developed. To realize such a concept, copper-coated polyurethane filaments were embroidered on a cotton fabric to design the heating element and an RTD-type temperature sensor. To ensure temperature self-regulation, an on–off control system referencing the temperature in real time was used to maintain the target temperature in the embroidered circuit, independent of the internal microclimate and external climatic conditions, as well as the battery voltage level . In addie wearer .Some studies have also looked at the combination of electric heating elements and functional heating materials to ensure better energy efficiency. In one of these studies, the influence of the use of phase change materials on the energy consumption of electrically heated garments was investigated . For thiBy using textile fibers, such as cotton, polyester, or acrylic, containing metals of ceramic compounds , fabrics with the ability to absorb, reflect, and emit far-infrared waves have been developed. Using such potential, heating elements have been proposed for protective clothing against cold in recent years . Some coThe study of commercial products for heating actuators was mainly oriented toward electric heating products for sustained heating. On the other hand, few or no products were identified in the other three categories of heating garments, i.e., those based on fluid flow, phase change material, or chemical heating garments.Indeed, commercially available electric garments use different technologies. Five types of technologies were defined in this study to classify companies and/or products, based on the review of scientific literature and information found on the websites of these heating product companies. The five types of technologies are conductive heating elements, electric heating wires, carbon fiber-based heating, graphene layer-based heating, and Positive Temperature Coefficient (PTC) conductive layer technology. Some types of technology such as conductive heating elements have been deliberately defined as quite generic, as it is often very difficult to know exactly what the technology of many products on the market consists of, as the information available on websites is often not very detailed, sometimes insufficient, or confusing. A sixth technology has been added but contains only one product that is distinct from the others. It is a face mask that warms and humidifies the air inhaled, which was first developed for people with asthma or respiratory disease (ColdAvenger). Nineteen of the companies identified were classified under the generic category of conductive heating elements because they provide very little detail on the heating technology used in their products on websites or data sheets. However, images, videos, and promotional interviews of these companies suggest that, for example, the heating elements used by some companies are based on conductive textiles , conductive elastomers laminated to textiles , printed heating elements , or heating elements knitted into clothing .® heating wire in seven different heating zones  for complete body heating. It also has three outlets that can power heating gloves (at different temperatures than the rest of the jacket), pants, and socks.Among the 13 companies analyzed that use electric heating wires, Interactive-wear produces heating textiles made with embroidered, single-layer Litz yarns that meet automotive quality standards to minimize the risk of hot spots. The Volt Smart Yarns company manufactures garments and heating textiles using different types of yarns . The other companies in this category produce heated clothing, but it is often difficult to have the details of the heating wire technology. For example, Gyde Wearable Technology announces that these garments contain micro-wire heating zones, but they do not provide more detail. Gerbing sells a jacket with a heat output of 77 watts, making it the warmest product Gerbing has to offer. The jacket contains more than 30 m of MicrowirePROTwenty-nine of the companies classified use a carbon fiber-based heating system to provide warm clothing such as jackets, vests, and shirts, as well as beanies, socks, or gloves. Duran, a Chinese company, claims to be the first company to have developed and commercialized carbon fiber heating yarns, and it is the only one capable of precisely controlling fiber strength during production to ±5% (per meter). According to their website, Duran holds 14 international patents and 18 national patents for electric heating products. A heating element made from carbon fibers can quickly reach the desired temperature in just a few seconds. It can even have a long lifetime, up to more than 1000 working hours, as for the Arris company’s heating vest with a constant temperature of 40 to 80 °C. For example, the information provided by the manufacturers’ website shows that Verseo uses very thin, stretchy carbon fibers, that Heated Gear and EGEVogue use a silver-coated polyester thermal lining to reflect heat in addition to the carbon fiber heating elements and benefit from a hybrid system, Colcham offers a safe heating system by providing short-circuit protection, and that Octocool claims to use more carbon fiber (60 to 80% more) in their heating jacket than other competing brands. Vinmori, a Chinese company, states on its website that it uses Toray carbon fiber from Japan to improve the emission wavelength of the heating panel to reach values of 3 at 14 μm, with most heating wavelengths between 2 and 10 μm and can cause greater heat dissipation. This company also uses a temperature control system that ensures that the heating panel can quickly reach its highest heating temperature in 3 min. In addition, a built-in NTC-type thermistor temperature sensor can automatically detect the panel temperature every 0.3 s. Thus, the heating panel can operate at the specified temperature, with the accuracy of 0.3 °C regardless of the external ambient temperature, and avoid excessive temperature that may expose the body to the risk of burns. In order to ensure a firmer and safer circuit, carbon fibers wrapped in a polyester film were considered. In addition, to ensure the electrical connections in its products, the company has favored the use of conductive wires with a thermoplastic elastomer resistant to low temperatures in order to maintain the mechanical strength of the wire and avoid its breaking even at −40 °C.Three of the companies listed use one heating technology based on graphene layers . According to the available information, this technology allows products that are light, resistant , durable, and offering good thermal performance. Graphene elements, in addition to allowing an equal and efficient distribution of heat, can be used safely in various conditions of temperature, humidity, or exposure to water and under high mechanical stress.Two of the listed companies, Nuova Heat and Nissha GSI Technologies, manufacture electronic textiles based on PTC technology for applications in the medical and industrial fields, such as aerospace, automotive, military, consumer goods, etc. The thermoregulatory PTC technology is based on a high temperature expanding resin layer that is loaded with conductive particles (often carbon). Such a film can control the temperature itself by regulating the heating power using its electrical resistance response to temperature, which varies with the expansion of the resin causing the distance between the conductive particles to increase. At low temperatures, its resistance is lower, so its heating power is greater, resulting in a rapid increase in temperature. As the temperature rises, its resistance increases, and therefore, its heating power decreases, thus controlling the temperature . Once deposited on a textile structure, the PTC layer heats evenly over the entire surface of the textile and self-regulates to a specific temperature, thus reducing the possibility of overheating the garment. According to manufacturers, products using PTC technology have the potential to be safer and even more efficient compared to those using more traditional yarn or carbon fiber technologies. PTC heating elements from Nuova Heat, a U.S.-based company, are manufactured by depositing a conductive ink printed on a nylon fabric containing traces of silver as electrodes that can reach 55 °C in a few seconds with the passage of a 9 V direct current. Only one company identified uses a technology based on a conductive carbon-based PTC layer. This is Kinesix Sports, whose product, which allows self-regulation of the heating temperature, is described in detail below. This company uses flexible, lightweight heating pads made from PTC-type carbon ink encapsulated between two extra-thin layers of polyester.In general, about 50 companies offer clothing and accessories that include heating technologies, mostly integrated in jackets and vests (sleeveless), but also in pants, body suits, gloves, socks, scarves, and beanies. Although 14 of these companies were only found on online sales platforms such as Amazon, most of them have a website where they present their products and features and sometimes explain the technology used. For jackets and vests specifically, two-thirds of the products listed have three heating zones, two of which are located on the chest and one on the upper back. In addition to these three zones, many products also offer heating zones on the collar to warm the neck, on the pockets to warm the hands, on the lower back and, for only a few products, on the sides of the body or on the arms. Most heated garments such as jackets and vests use a lithium-ion battery , which allows the heating elements to provide heat higher than body temperature. In addition, many of the commercially available jackets and vests have USB ports that allow the battery to be used to charge mobile devices. Two-thirds of jackets and vests allow three temperature settings, for example, 25 °C/35 °C/45 °C for some products or 45 °C/55 °C/65 °C for others. These settings provide continuous heat for periods of time that can be, for example, around 15 h, 7 h, and 5 h for some products, or 4.5 h, 3 h, and 2 h for other products, depending on the temperature supplied and the power available. Usually, an LED control switch is integrated into the chest of the garment to allow the user to adjust and interpret the heat settings at different levels. Most commercially available products can be washed according to the manufacturer’s instructions. They are mainly aimed at the sports, leisure, or generic markets. A few garments and vests stand out because of their particular features or performance. For example, some companies offer heated shirts, jackets, or vests with plugs that allow the same energy source to be used to connect heating gloves , heated pants, or heated socks . Other companies offer independent heating zones to separately adjust the temperature of certain areas, such as the front, back, and hands (via garment pockets) (Arris), front and back (Vinmori), or body and hands (Ptahdus). Some companies offer continuous adjustments of the heating temperature via a variable switch (Warm & Safe Heated Gear) or with the help of a smart phone application .In addition, this study identified three companies that have implemented systems that allow self-regulation of the heating temperature thanks to integrated thermal sensors that measure the temperature inside the garment or that of the skin. Clim8 proposes an intelligent thermal system integrated in a textile panel, in the form of a sweater adjusted to the body. This sweater is equipped with thermal sensors integrated in the fibers and controlled by a smart phone application. Once the temperature is set by the user, the sensors measure in real time the temperature of the microclimate, and the system activates when the temperature detected by the sensors is below the reference threshold and deactivates above this temperature. The mobile application of this system still allows manual activation and control of the garment heating. The company announces that the heating elements are positioned on the vital parts of the body. However, the available images and videos show that the technology seems to be present at least on the front and back of the sweater. Other companies such as Odlo and K2 also use Clim8 technology. Odlo has developed, with Clim8 and Twinery, the I-Thermic system integrated into a knitted sweater that can be worn alone or under a jacket. Although few details are provided on Odlo’s website, it seems that the heating elements are knitted in the shape of a coil. The company says that with this option for total control of the personal microenvironment, it is not necessary to wear an extra layer under the winter sports jacket. Equipped with a battery offering 4 h of autonomy, Odlo’s I-Thermic sweater seems safe, since the heating elements and software are set not to exceed 37 °C and stop immediately in case of higher temperatures, avoiding overheating.2 and methane levels, noise level, etc.) of a workplace.In association with Helly Hansen, the Canadian company Myant has announced a line of active thermal workwear that provides thermal regulation for low-temperature environments. These garments feature an electronic textile layer and include a base layer top, leggings, socks, balaclava, and gloves. Equipped with textile heating elements and integrated temperature sensors, the system detects the skin temperature and the temperature of the microclimate close to the body to trigger a reaction by actively supplying heat through the textile to regulate the temperature. Being designed using advanced knitting technology, these workwears have a tailored design to better keep the sensors and actuators in contact with the body. Note that the company Myant, according to the information available on its website, seems to have the will to contribute to the future of work through smart textiles, artificial intelligence, and the Internet of Objects. In addition to a platform to measure the physiological parameters of workers with smart textiles, they want to be able to measure the environmental conditions . Some offer clothing that can be worn under a uniform or work clothing . Others offer high-visibility heated jackets, vests, or hoodies . Finally, five companies offer products dedicated to workers: Milwaukee, Dewalt, Bosch, Makita, and Myant-Helly Hansen (including an intelligent garment offering self-regulation of body temperature that was described above). Among the range of products for use in the workplace, Makita’s jacket provides 28 h of warmth with an 18 V battery.Among the different categories of heated clothing designed to provide better comfort during activities in extreme cold, this study focused on electric heated clothing providing continuous heat within the limits of their energy sources, while offering the possibility of developing space-saving structures with a reduced thickness .Despite a very good potential, at the current state of technological advancement, PCM-based garments do not have the capacity to provide sustained and durable heat throughout a working day in a cold environment due to the temporary heating effect of PCM-based heating elements, the low thermal effect and durability problems of microencapsulated PCM coated on the textile, and the high weight and reduced sweat evacuation in PCM pocket-based garments. Therefore, significant work is still required to achieve a sustained heat effect from PCM garments.In order to overcome the disadvantages of the conventional use of electric heating wires, heating elements based on conductive textile fibers have been developed in recent years. Within this context, several methods have been proposed to design heating elements based on metallic textile wires  or based on metallic compositions . However, the analysis of the research work has shown that obtaining such textile heating elements requires the control of many parameters. Concerning the heating elements designed with the embroidery of metallic (textile) threads, the number of thread passages, the spacing between the threads, and the composition of the base fabric have an impact on the heating temperature and the level of electrical power required. Despite the advantages of heating elements embroidered with metallic threads in terms of energy consumption, research is still needed to better control the influence of the fiber content of the base fabric and the enlargement of the size of these heating elements. Despite the advantages of a flexible and stretchable structure of the knitted heating elements, their design is also a technological challenge. It has been shown that the thermal effect achieved in heated knitted fabrics depends on the type of conductive yarn, its mechanical properties, the structure of the knitted fabric, the knitting method, the composition of the textile fibers surrounding the conductive yarn in the knitted fabric, and the number of plies in a possible multilayer structure. It has also been shown that with the right design and conductive yarns with appropriate electrical resistance, knitted heating elements working with low power supplies could be developed. In a possible approach to integrating knitted heating elements in protective equipment, special attention must be paid to such parameters, in particular the structure and composition of the layers constituting the workwear.In order to facilitate the design of electric heating elements based on metallic textile yarns, some mathematical models have been developed to predict the thermoelectric behavior of heating fabrics or knitted fabrics . With thHeating elements with versatile designs can be formed on the surface of flexible substrates using coating techniques. Silver particle-based coatings ensure low energy consumption and very short times to reach the maximum equilibrium temperature. However, their low washout durability can be a very important shortcoming. In addition, coatings based on silver nanofilaments have poor stability in ambient air. Therefore, encapsulation techniques would be necessary to protect them in a possible integration process in protective equipment. Despite the flexibility and lightness offered by the coated layers based on conductive polymers and their ability to provide stable heat at high temperatures, they require a fairly high energy consumption and present certain failures from a mechanical resistance point of view. On the other hand, carbon fibers have been the subject of research work as well as numerous industrial developments in recent years. Indeed, due to their good thermal efficiency, rapid attainment of uniform heat, rapid recovery of the initial temperature when the power supply is switched off, and a very high electricity conversion rate, carbon fiber-based heating elements are ideal candidates for the implementation of precise temperature control. However, further research is needed to optimize the wash resistance and energy consumption of carbon fiber heating elements.Despite the large number of studies dedicated to the development of new types of heating elements, little work has been done on the design or efficiency of heating garments. Furthermore, few studies have been devoted to the use of heating garments in a work context or to the development of protective equipment with heating elements. Indeed, most studies have been carried out in the laboratory with few human subjects. As some studies have highlighted a difference in the sensation of comfort expressed between male and female subjects when using heated clothing, more investigation is also needed in order to define the optimal heating conditions. Based on the results of previous studies, the impact of factors such as the combination of the heated garment with other clothing or environmental conditions on the performance of the heated garment in a work environment should be studied in order to obtain the best possible thermal performance. Extending the research on conventional (electric) heated gloves, the influence of the structure of the heating element as well as the design of a protective glove with heating elements on the dexterity of the fingers remains to be studied. In addition, the association of electric heating elements with far-infrared wave reactive heating panels or PCM-based heating elements to ensure a better energy consumption efficiency proposed in the literature is one of the concepts that remains to be explored in the structure of protective equipment and an active work context. The association of temperature-sensitive shape memory materials with electric heating elements allowing the placement of textiles with insulation properties that vary with the level of heating, used as a means to control the overall degree of insulation of the fabric, is another concept that could be applied to protective equipment to provide better protection to the worker.As with the literature review, research on products containing heating actuators has focused mainly on electrical heating garments. As this is a dominant technological trend and there is strong industrial competition between the various players in this sector, several companies did not provide any information regarding the technology used in the design of the electric heating elements of their products. Despite all the known limitations of electric wire-based heating elements, this technology still seems to attract the attention of a significant number of manufacturers because of the simplicity of its implementation. However, because of the advantages of using carbon fibers in the design of heating elements, this technology seems to be the new trend among manufacturers. Positive temperature coefficient (PTC) heating elements are also a growing category of technology because of their ability to self-regulate the heating temperature to a specific level. Due to numerous advantages such as quick response to temperature change commands, good thermal efficiency, uniform heating capacity, etc., carbon fiber or PTC-based heating elements can form the basis for future work on the integration of heating elements in personal protective equipment.The analysis of commercial products has also shown that more and more warming garments allow several areas of the body to be heated, while enabling the temperature to be varied using an integrated control switch or wireless temperature control. Although a number of these types of electric heat garments are also intended for workers in different industries, the heating zones are fixed, and temperature settings are often limited to three levels and restricted temperature ranges. Not only are these products unable to provide a customized solution, but such structures can also present serious overheating problems when used during intense work activities. Therefore, the few products offering independent heating zones and allowing interruption or adjustment of the temperature of each zone separately, as well as garments offering temperature control using a variable switch may be of interest for adaptation to use in work environments. In future work, it may be important to study the impact of independently controlling the heating temperature of different parts of the body based on the heat loss of different parts of the body, which can vary considerably depending on physical activities performed and the type of equipment worn .Thanks to advances in portable technologies, a limited number of products that allow self-regulation of the heating temperature using integrated thermal sensors that measure the microclimatic temperature inside the garment or the skin have been launched on the market over the last two years. As this is a very recent technology, the effectiveness of such systems, as well as their impact on the physiological aspects of people performing cold work tasks, remains to be studied. In addition, the integration of self-regulating temperature actuators into personal protective equipment structures requires significant research efforts.Among the various means of intelligent thermal management, cooling actuators are the technological solutions most dedicated to the occupational health and safety application. Since the evaporation of sweat is the most efficient way for the body to cool down, it is practically impossible to do so when wearing fully enclosed protective equipment such as protective clothing against chemical, biological, radiological, or nuclear CBRN hazards . In addiPersonal cooling garments can be divided into two main categories according to their passive or active cooling system. Passive cooling garments include conductive, phase change (PCM) cooling, and evaporative cooling elements. Active cooling garments include thermoelectric, air ventilation, and circulating fluid coolers ,229. WhiThe present study was particularly interested in the analysis of active cooling garments that could provide sustained cooling, depending on their power sources. For passive cooling garments, the detailed analysis focused instead on conductive and evaporative cooling elements. As the integration of PCM cooling elements in garments has been studied in various studies, their state of the art has been widely documented ,60, demoIndeed, PCM cooling garments use the energy of latent heat to maintain the microclimate temperature close to the skin temperature. The cooling mechanism is based on the melting of a substance going from a solid state to a liquid state that allows the absorption of body heat transported to the skin surface. This type of cooling is effective when PCMs change from their solid to liquid phase. Therefore, the cooling effect is only effective within a narrow temperature range of the microclimate that triggers a phase change of the material ,58. BeinTo overcome these problems, experts proposed the coating of microencapsulated PCM on fibers or fabrics. However, as the amount of microencapsulated PCM inserted into textiles to ensure thermal productivity increases, the permeability  of the fabric decreases. In addition, as the stiffness of the fabric increases, its softness and flexural strength decreases. Furthermore, despite efforts to improve the resistance of PCM microcapsules to washing, abrasion, and high temperature, it has been reported that the material can lose up to 60% of its heat storage capacity after a few washes . With rePersonal cooling garments were initially developed to reduce the effect of thermal stress in hostile aerospace and industrial environments. Even if the first developments date back 50 years, research on the optimization and effective integration of these devices into clothing continues .According to a first observation, a large part of the work on cooling garments is dedicated to fluid cooling garments (FCG). These garments employ a conduction cooling system that circulates cooled fluid inside a garment close to the skin surface. The cooled fluid can be a liquid such as water or compressed or ambient air. A network of pipes attached to the inside of the garment conducts the cold fluid through the garment and returns it to a cooling device after conduction heat exchange with the body. The cooling system typically contains a pump, a reservoir, and a control valve . To dateSince the conduction mechanism requires direct and continuous contact between the tubular network of FCG and the skin, the contact pressure and the uniformity of tube distribution could have a major impact on the heat exchange between FCG and the body. In order to promote this heat exchange, the inner textile layer of FCG to be worn close to the skin should have good thermal conductivity and provide good moisture management, while ensuring a good fit to the body and good tactile properties. In addition, the material of the tubes, their thermal conductivity, overall length, internal diameter, and wall thickness, as well as the flow rate and temperature of the circulating fluid are other parameters that influence the effectiveness of FCG. The distribution of the tubes is another important factor affecting the efficiency of FCG in cooling different areas of the body or intermittent and regional cooling. In addition, liquid and air-cooled garments are limited by their required power and total system size ,231.As a result, several studies have been devoted to the optimization of FCG design in recent years. In this context, the comparison of two water FCGs of identical tubular networks but different textile structures on a thermal manikin have shown that the type of knitted fabric used to contain the tubes greatly affects the heat transfer in the garment. For example, double Jersey fabrics with naturally curved structures that accommodate the tube would provide a better cooling effect than single Jersey fabrics that require additional material, such as foam interlining, to accommodate the tube, leading to a lower heat transfer coefficient . As an iAs part of the development of FCG for a space suit and in order to determine whether the capacity of the mechanical pump was appropriate for this system, the heat removal capacity of the system was determined by applying a thermodynamic heat exchange model. The equation was subsequently validated by comparing the theoretical values with the values obtained by thermocouples recording the entry and exit temperature of the FCG suit . In anots of 34.5 °C and deactivated at a Ts of 33.5 °C, demonstrated longer periods of heat stress management compared to continuous and intermittent cooling modes [s feedback to activate an FCG when Ts was in the range of 33 to 35 °C [s of the individual could reduce thermal stress in the same way as constant cooling [Some experts have proposed the presence of a cooling control system in FCG garments to adjust the temperature and flow rate of the coolant circulation according to the microclimatic temperature changes close to the skin. Thus, with the decrease in metabolic activity, the wearer of the garment would not experience undesirable body heat loss and thermal discomfort due to excessive cooling . Indeed,ng modes , and it to 35 °C . Thus, i cooling .s without increasing the moisture content of the garment. However, the cooling effect was delayed until a sufficient dose of water was released and evaporated [s without causing an increase in garment moisture from the start of cooling [As in humid environments, water circulation in the space between the skin and the dense layers of personal protective equipment can lead to the appearance of steam and cause skin burns; thus, researchers have proposed water-based FCG garments with a self-transpiration capacity induced by oozing water from 20 pores in the tubular network for cooling with heat loss by evaporation . The selaporated . The sam cooling . DespiteMore recently, nanofluids have drawn the attention of scientists due to their high rates of heat transfer, which allows them to be used in various industrial uses. A new class of nanofluids, “hybrid nanofluids”, has recently been used to further improve the rate of heat transfer. The current phenomenon particularly concerns the analysis of the flow and heat transfer of SWCNT  MWCNT /water hybrid nanofluid with activation energy through a moving wedge . Howevers and Trec values of individuals, thereby enhancing worker productivity in a hot, humid environment with a relatively lighter portable cooling system compared to similarly sized FCGs operating with cold water [In order to overcome some limitations on the use of cold water in an FCG garment with respect to the weight of the cooling tank or the influence of ambient heat on the water temperature, some research has proposed the use of other liquids to be circulated in the tubular network of FCG ,245. Evald water .FCG garments using air circulation in an integrated tubular network have also been the subject of recent studies. Examination of an air FCG garment with a stationary compressor generating dehumidified air blown through a tubular network covering certain body regions under a chemical protective suit has shown that such a device would significantly reduce the effect of thermal stress. Tests carried out on human subjects have also shown that with this type of clothing, working hours could be considerably extended .2), based on the distribution of CO2 at high pressure through a pressure relief valve in which the gas pressure drops to ambient pressure  to ensure better performance in hot and humid climates .To evaluate the performance of PCM/fan hybrid cooling garments, a prototype containing four fans and 24 pockets of PCM  and a gac, mean Ts, HR, and PSI, while improving subjective perceptions during exercise and recovery phases [A study conducted on human subjects concluded that PCM/fan-cooling garments could effectively reduce heat stress during exercise in a warm, moderately humid environment. Indeed, the use of a suit containing 18 PCM pockets in the upper body and six thigh pockets in combination with two ventilators on the lower back of the jacket and two ventilators on the lateral pelvis of the pants reduced subjects’ Ty phases .s and total sweat production of subjects, who also expressed good thermal sensations, skin moisture, and comfort compared to tests without cooling [A similar combination of 24 PCM pockets and four fans was also validated for a warm indoor environment simulated by a climatic chamber by demonstrating a reduction in the mean T cooling . The eff cooling .c and HR and improve their subjective perceptions [s. The study suggests the use of such a design for moderate physical activities in a hot environment thanks to an extended duration of the cooling of the PCM ensured with the presence of an additional insulation layer [A few studies have also been devoted to optimizing the design of PCM/fan garments to ensure better management of cooling energy using an additional layer of insulation in the garment structure ,303. A von layer .A similar study taking into consideration the same arrangement of 24 PCM pockets and four fans placed in the jacket and pants of a suit proposed the integration of an insulating layer composed of polyethylene foam on the outer surface of the PCM pockets to reduce the heat absorption of the hot environment and extend the operating life of the PCM used. Subsequently, Tanabe’s thermoregulation model coupled with a model of heat and moisture transfer through the garment was used to numerically study the performance of this new hybrid cooling garment. According to parametric digital analyses, the environmental heat absorbed by the PCM can decrease thanks to the increase in thermal resistance provided by an additional insulating layer. The validation of the model by tests carried out on males in a hot and humid climatic chamber also demonstrated that the presence of an insulating layer in the structure of a garment with PCM/fans could considerably reduce the environmental heat absorbed by the PCM. Thus, the total PCM melting time and the effective cooling time could increase .c and Ts values, high ambient temperature and RH ≥ 70% would weaken the performance of such a suit. However, for better cooling efficiency in conditions of very high environmental temperatures or RH, the properties of the PCM used and their level of insulation should be optimized [Some work has also been devoted to the numerical analysis of the performance of PCM/fan garments under different conditions ,304,305.With the development of advanced materials and the progress made in the elaboration of conductive textiles, these types of concepts have also been exploited for the implementation of passive cooling strategies in textile structures ,307,308.®, being a selectively and highly water-permeable, sulfonated tetra fluoro ethylene-based fluoro-polymer copolymer, has been the subject of recent work to develop a reversible moisture sensitive garment to support personal thermoregulation in warm environments. For this purpose, smart textile structures based on Nafion®, activated by moisture change, have been developed with the ability to rapidly and reversibly change their porosities or thermal insulation levels in response to the individual’s level of perspiration [® could respond to a moisture gradient by automatically opening or closing to regulate the flow of air through the pores, thus providing humidity and temperature control. Nafion® tapes inserted between two layers of variable thickness have also demonstrated the ability to adjust the air gap and change the thermal insulation between two layers of fabric [It has also been reported that mixing phase change materials with active cooling components such as metals and/or highly conductive ceramics and encapsulated soluble alcohols such as xylitol that cool in contact with water vapor could allow a PCM to repeatedly lose heat and thus create an effect similar to a recharging of the cooling effect of the PCM during exposure to heat. A study has shown that depositing a mixture of PCM/highly conductive metals on the surface of a sweater could allow the development of a textile layer creating a multistage cooling effect . Nafion®piration . Indeed,f fabric . Figure Shape memory polymers have also shown great promise in the development of thermoregulating textiles. These materials sensitive to external stimuli have the capacity to memorize a permanent macroscopic shape, be manipulated and fixed to a temporary shape under specific conditions of stress, and then later return to their original state by no longer being subjected to thermal, electrical, or environmental stress ,315,316,Concerning temperature-sensitive shape memory polymers, large changes in thermomechanical properties occur across the glass transition temperature of the melting point temperature of the crystals of their soft segment. In addition to these changes, it has also been shown that this type of material may exhibit changes in moisture permeability above and below this point . For texThe material may return to a less permeable structure when the temperature drops . DespiteMultilayer garments are another area for improving the performance of conventional evaporative cooling garments. This approach involves the integration of hygroscopic materials, of the desiccant or super-absorbent type to promote the absorption of the vapor produced by perspiration or by the liquid included in an internal reservoir . Based oCommercially available cooling garments use different technologies. Although the current study focuses primarily on active cooling systems, several commercially available products use PCM, a passive system, as the cooling technology (12 products). Most of the products are sleeveless vests, most often available in one size (or two sizes), with adjustment straps around the torso to ensure as close contact with the body as possible. The vests are equipped with PCM pockets on the front and back. Most companies do not provide details on the phase change materials used, claiming that their material is lighter and more effective than water or frozen gels and safer than ice water for the skin, which can cause frostbite. However, FlexiFreeze uses frozen water as a cooling principle but with specific packaging, claiming that for the same weight, water is a more efficient means of cooling than frozen gels. The company offers a vest with 96 ice cubes distributed on the front and back, weighing 1.4 kg. The FlexiFreeze product, similar to the AlphaCool Ice Vest, using a water-based product, has packaging that slows down the melting of the ice. Techniche uses pockets containing a non-toxic, non-flammable, and non-combustible carbon-based liquid. Overall, the majority of identified cooling vests appear to have similar properties: a temperature around 15 °C, a cooling period of approximately 2 to 3 h, a cooling capacity reactivation time of approximately 35-45 min, and a weight varying between 1.0 and 2.3 kg. There are a few exceptions. For example, AllTuff USA PCM vests are available in three charging temperatures, 5 °C, 15 °C, or 25 °C. The Ergodyne vest allows a reactivation time of 5 to 15 min. ClimaTech Safety’s CM2000 vest can provide an extension of the cooling period from 2 h (standard) to 4 h with the addition of another cooling layer attached by Velcro over the first layer.Of the commercially available products using a passive water evaporative cooling system, three are presented herein. The first product is a thin, light, and flexible combination of a sleeveless shirt and shorts, which was developed by UNICO Swiss Tex GmbH. This close-fitting suit can be worn underneath clothing. It is made of a three-layer laminate consisting of two waterproof but breathable polyester membranes that cover a hydrophilic fabric . The fabAs a hybrid cooling system, one of the most interesting is that of the SurgeCool company, which has developed a vest using two technologies: a liquid circulation cooling system (active) combined with a frozen gel cooling system (passive). Instead of being equipped with a large ice tank (stationary or portable) and an injection pump, as most liquid circulation cooling systems are, SurgeCool replaced these elements with a gelling polymer pack. The liquid circulating through the vest tubes is cooled to a temperature of approximately 18–22 °C by the cooling pack, which will gradually melt and lose its cooling effect after 2 h. This assembly of the two technologies allows a more global cooling effect of the body, spreading the cold from the cooling pack over the whole vest in a certain way and for a longer period. The vest, with a single cooling pack, can be worn with the refrigerant pack on the front or on the back depending on the user’s work preferences. The vest weighs less than 1 kg.UNICO Swiss Tex GmbH has developed a ballistic cooling vest together with the Empa Research Institute (Switzerland) that also uses two technologies: a passive evaporation system and an active system with fans. A panel, Coolpad, is filled with water, which evaporates through a membrane, cooling the panel. According to the company, the existing Coolpads were unsatisfactory: being subjected to high mechanical stress in the vest, they often leaked. Fortunately, a new laser diode welding technique has made it possible to produce thin, flexible, and reliable panels that do not leak, despite the mechanical stresses to which they are subjected. Two fans blow air through a spacer knit behind the Coolpad and provide additional cooling. The compression-stable, flexible spacer knit with low resistance to airflow was developed in cooperation with the Eschler company. A water refill is required for approximately three hours of use. The two fans, which can be recharged from a socket or a car cigarette lighter, can last three to four hours. This ballistic vest has been tested with the police officers of the Zurich City Police, who appreciated it. Finally, Techniche also offers a hybrid cooling product, simply combining two passive systems in the same vest: their PCM technology, CoolPaxTM, with their water evaporation technology, HyperKewlTM PLUS.Cooling actuators are the most studied technological solutions in an occupational health and safety context among the various means of intelligent thermal management .An important part of the research work on personal cooling garments has been devoted to fluid circulation cooling systems. Although their effectiveness has been approved by several studies, these garments are heavy and cumbersome and seem practical only for occupations in which workers do not travel frequently, such as workers working in vehicles with the refrigeration unit or compressed air system at a standstill. In addition, cooling units consisting of an ice cube tank, proposed for better portability of the system, remain limited due to the operating time and require frequent recharging of the tank. Furthermore, recent studies on the optimization of parameters such as the textile layer design of the fluid circulation cooling garments, their tubular network, their assembly, the capacity of their fluid injection pump, circulation flow rate, etc., seem to be limited to validation tests in the laboratory and on very few human subjects.The automatic control of the appearance of steam around the tubular network to reduce the risk of skin burns in humid environments and the use of PCM suspensions to improve heat dissipation without an apparent increase in pump power are examples of other concepts proposed for optimizing the performance of cooling garments through fluid circulation, which generally operates with cold water. However, tests in operational environments are still needed to validate these concepts. Although many studies are devoted to fluid cooling garments, this analysis identified only two studies that were conducted in an operational environment.s feedback activation would reduce system energy consumption and the risk of overcooling while improving efficiency. However, all work on these systems has been limited to tests on thermal manikins and few tests on individuals in the laboratory.Fluid circulation cooling garments with integrated temperature and flow rate control systems using intermittent or alternate circulation and Ts or Tc. Despite optimization work on fan placement, additional openings in the clothing, or intermittent cooling modes, no particular benefit could be observed in the studies analyzed. On the other hand, the few studies devoted to the thermoelectric cooling garment seem to be limited to proofs of concept and show a relatively high electrical energy consumption in their current state. However, the small dimensions of thermoelectric modules, combined with recent work on flexible module design, suggest that portable thermoelectric solutions with heating and cooling capacity can be implemented. In order to overcome the low efficiency of evaporative cooling garments worn under dense protective equipment and in humid environments, the introduction of a ventilation mechanism to evacuate moisture, or motorized vapor compression devices associated with cooling lines, have been proposed. In their current state, these concepts are cumbersome and impractical to carry to work.In order to take advantage of the relatively low weight and high cooling capacity of gas expansion cooling garments, while circumventing their limitations in terms of low operating time and exhaust gas, very recent studies have proposed some optimizations for use in hot and humid environments. These results have yet to be confirmed under real operating conditions. In addition, design modifications are still necessary to facilitate their use under protective equipment. The literature review also revealed that despite the greater efficiency of air blast cooling garments using an air compressor, most of the work had favored cooling by fan ventilation for better portability of the system. Although fans allow a good decrease in the humidity of the microclimate close to the skin, their performance seems to be influenced by the temperature or humidity of the ambient air and, according to some studies, their beneficial effect lies at the level of the local Ts without a remarkable influence at the level of the total TVacuum desiccant cooling garments have a high cooling capacity, as they involve hygroscopic materials to improve the performance of evaporative cooling garments . Howeverc and Ts. They are also limited by the lack of a vasoconstrictor response initiated in human skin when cooled [Despite comparative studies and the establishment of generic tables comparing the performance of various cooling systems, the selection of the most appropriate system is sometimes a complex task. One of the reasons for this difficulty is the shortcomings of the test methods used to evaluate the various types of personal cooling garments. Many studies have used thermal manikins. Although useful for a first draft, manikins cannot adequately simulate the spatial and transient thermal behavior of humans or realistic thermophysiological responses, such as changes in Tn cooled .In addition, testing on human subjects is mostly limited to a restricted number and gender. In addition, differences in methodologies , subject characteristics , and cooling system properties  sometimes lead to confusion about the results presented in the literature. Indeed, the diversity of experiments and methods has sometimes led to different results that are not necessarily confirmed and are sometimes contradictory. For example, the impact of technology on physiological parameters may vary from one study to another. In addition, the application of laboratory results in the field may be compromised by ergonomic problems in a real work environment due to the varied and complex forms of movement in comparison with the simulated treadmill running-type tests adopted in many studies. In order to facilitate the choice of the appropriate system, some universal methods have been proposed for theoretical calculation of the performance of the cooling garment according to the climate and the nature of the activity. However, these methods do not consider the loss of body heat and the impact of cooling on the physiological aspects of the body, which can vary from person to person.Faced with the complexity of selecting the best strategy for different environments and activities, and to circumvent the limitations of different systems, some experts have proposed hybrid cooling technologies. The combination of frozen gel pads with fans for a greater reduction of physiological constraints in the activity phases, and the circulation of cold water through PCM pockets to increase the operating time, have been the concepts explored through a limited number of studies. However, the review of the literature revealed several studies concerning hybrid cooling garments combining PCM actuators and fans (PCM/fans) in order to promote heat loss by evaporation using fans and to create a synergistic effect to obtain better performance in hot and humid climates while ensuring portability. The integration of insulating layers to reduce the environmental heat absorbed by the PCM in optimized versions of PCM/fan garments has increased the total melting time of the PCM and the effective cooling time. Despite great potential, moisture condensation on the surfaces of the PCM pockets, reducing the efficiency of the system, and the weight of the PCM pockets have proven to be two limitations of this type of hybrid cooling garment. Furthermore, a hybrid PCM/fan system has not yet been explored in a protective equipment structure.In addition, the design of high thermal conductivity layers based on advanced materials or conductive textiles to improve the heat exchange of the garment, the mixing of PCM with conductive materials to create an effect of repeated heat loss, the use of materials reversibly sensitive to humidity or temperature have not yet been explored in association with active cooling systems in the design of hybrid cooling garments. These types of materials should also be studied in the optimization of the thermal performance of personal protective equipment. In view of the progress made and the use of new technologies in the design of personal cooling garments, the decision on the effectiveness or ineffectiveness of these new systems in reducing the body’s thermal stress requires more studies, modeling or simulations, in order to judge their performance under particular conditions.Concerning research on products containing cooling actuators, analyses have shown that almost half of the products identified use passive cooling principles such as PCM or evaporative cooling. As in the scientific literature, most cooling garments based on liquid circulation or compressed air are stationary and less intended for workers who must move frequently. Despite the relatively simple design of fan cooling garments, no protective equipment containing integrated fans could be identified in the analyses. Gas expansion and thermoelectric systems appear to be still under development and not widely available on the market. Despite a great deal of research work dedicated to hybrid systems, there are few products combining two types of technologies. Moreover, none of these products combines an active fan system with a passive PCM system, even though they have been praised in the scientific literature.Despite the standards governing working conditions and the advances in the development of more efficient protective equipment, thermal constraints remain a major occupational health problem. In such a context, thermoregulation systems, which make textiles capable of detecting, reacting, and adapting to thermal stimuli, offer great potential for improving the performance of personal protective equipment during exposure to extreme temperatures.Therefore, the present study was conducted in order to better document the current state of knowledge on the technologies facilitating intelligent thermal management by reviewing the existing technologies currently available on the market and the developments carried out in the framework of previous research work. Particular attention was paid to the collection of scientific and technical information on systems that can potentially be integrated into personal protective equipment for intelligent and sustained thermal management throughout the execution of tasks. Based on the knowledge gathered and discussions on the current gaps in studies and marketed products, the efforts still to be done and the development or adaptation strategies to be deployed in personal protective equipment were discussed.Indeed, the potential of smart textiles and advanced functional materials can be greatly exploited in the development of integrated temperature sensors, heating or cooling actuators, and wearable devices or in the optimization of their performance. The use of advanced functional materials in combination with active cooling or heating technologies to establish hybrid systems providing improved performance are among the most viable solutions to implement in the short term. Moreover, combining two cooling or heating technologies to create a synergistic effect to optimize the performances is one of the most interesting strategies to consider. Finally, the results of numerous laboratory studies and some products recently developed in the industry remain to be deployed in workplaces through field studies.


Atherosclerosis is a pathological vascular state caused by the interaction of environmental and hereditary factors. Epigenetic modifications may be the bridge connecting environmental factors and genetic factors. A search for publications on the Web of Science database in the field of atherosclerosis related to epigenetics was conducted from the earliest mention to 31 December 2020. Data on total and annual publications, citations, impact factors, Hirsch (H)-index, citation times, most prolific authors, and frequently published journals were collected for quantitative and qualitative comparison. A total of 1848 publications related to epigenetics and atherosclerosis were found. The major contributing countries were the China , United States , and Germany . The greatest number of retrieved publications were published in the journal, “Arteriosclerosis, Thrombosis, and Vascular Biology” . The publication “Oxidative Stress and Diabetic Complications” was cited 2370 times. The most frequent keywords were “DNA methylation” and “LncRNA”. Publications on epigenetic research in the atherosclerosis field have increased significantly every year, indicating that the study of epigenetic modifications plays an increasingly important role in understanding the pathology of atherosclerosis. Atherosclerosis is a chronic inflammatory disease manifesting with pathological changes in the cardiovascular system caused by the interaction of environmental and genetic factors . The envEpigenetic modifications include all types of genetic changes that modulate gene expression without involving potential changes in DNA sequence . It alsoBibliometric analysis is an important tool to evaluate the latest trends in current scientific research . This teIn this manuscript, bibliometric tools were used to analyze publications related to atherosclerosis in the epigenetic field retrieved from the Web of Science (WOS) databases. Previous studies have often been presented in the form of still images, and interactive images are used in our paper to show the correlation between research contents in the field of atherosclerosis in the field of epigenetic modification. The innovation of this paper lies in the visual analysis of the research hotspots and trends related to atherosclerosis in apparent modification as well as previous research emphases, which has guiding significance for researchers involved in related fields. Over time, the research focus of atherosclerosis epigenetic modification has shifted from DNA methylation to lncRNA.http://www.webofknowledge.com/, accessed on 3 July 2020), we conducted a bibliometric analysis of the research results from the earliest mention in 1978 to 2020 by online bibliographic retrieval as of 31 December 2020 [Based on the publications in the WOS database , year of publication = , and language = English.All the retrieved publications were filtered to remove duplicate publications. Data entries and collections were verified by two authors (Linying Jia and Ao Cheng).The total records of papers from the WOS database, including publication year, title, authors’ names, affiliations, nationalities, abstracts and key words, journal names, etc., were saved in Txt format and opened by Excel 2019. Our collaborators, Linying Jia and Ao Cheng, browsed and extracted the data from these publications. Any disagreement was resolved through a meeting to reach a final consensus. Lastly, the extracted data were analyzed by Microsoft Excel 2019 and VOSviewer.From the downloaded data, Microsoft Excel 2019  extracted the number of papers published by each country, the percentage of the total number of publications, the citation frequency of publications in this field for each country, and the average citation frequency. In addition, the contribution of each institution and the major journals in the field were extracted and depicted as a histogram from the downloaded data. Scientific networks also allow analysis of many publishing characteristics, including country and region, institution, publication time, author, and cited frequency.https://www.vosviewer.com/ accessed on 3 July 2020). This software can extract the author, institution, abstract, country, and other related information from literature search data. These can then be used for visual analysis; mapping of scientific knowledge; and illustration of the structure, evolution, and cooperation within a specific area of knowledge [VOSviewer is a visual bibliometric network-building software developed by the Center for Science and Technology Studies (CWTS) of Leiden University in The Netherlands , indicating that atherosclerosis is a rapidly developing research area in the epigenetics field a. Among United States publications were cited the most  with China ranking second (8151 times), followed by Germany (4366 times), England (3143 times), and Italy (2381 times) a. In terThe h-index is an indicator of the scientific impact of an academic publishing career . A countThe contribution of institutions to a certain field is very important; the three most productive sources in the field were Washington U. , Harvard U. , and Karolinska Inst.  .The journals with the largest number of publications were ‘Arteriosclerosis Thrombosis and Vascular Biology’ , ‘Atherosclerosis’ , and ‘Plos One’  .The publication “Oxidative Stress and Diabetic Complications” was cited 2370 times. It is the most frequently cited publication and has important guiding significance for the research in this field.Atherosclerosis (9280), Vascular Pharmacology (6688), Arteriosclerosis, Thrombosis, and Vascular Biology (6636), Circulation Research (5519), and the International Journal of Molecular Sciences (5169).Literature coupling reflects the relationship between two bibliographies in terms of similarity of citations. Bibliographic coupling occurs when two papers cite the same reference in their respective bibliographies. This indicates that there may be internal relations and rules between two publications. The journal names of all publications were analyzed by VOSviewer. As can be seen in The publications from 78 institutions were analyzed by VOSviewer and the minimum number of documents for inclusion of an organization was more than 10 b. The fiThe publications from 29 countries were analyzed by Vosviewer, and only those countries with at least 12 documents were included c. The fiCo-occurrence analysis refers to the phenomenon that the same or different types of feature items appear together. The purpose of cooperative analysis is to determine popular areas and development directions for cooperative research. This has proved to be very important in the development of science monitoring systems and other disciplines. The title and abstract of the retrieved literature were opened through VOS Viewer software. The software associated the repeated keywords, set the frequency of keyword occurrence not less than 30 times, and generated interactive visual analysis images of the selected keywords through the software. As shown in Epigenetic processes are highly dynamic and reversible, and have specific ‘writers’ and ‘erasers’ that regulate gene expression. Targeting these epigenetic processes offers a great opportunity for discovery of new ways to prevent and treat atherosclerosis . The VOSArteriosclerosis Thrombosis and Vascular Biology was the most closely related journal. The key words in the titles and abstracts of the included studies were analyzed to yield a map showing the collaborative network [With the recognition that epigenetic modifications have a key role in atherosclerosis, the number of publications related to atherosclerosis in the epigenetic field began to increase every year from 1995 to 2020. This shows that atherosclerosis research has experienced rapid development in the field of epigenetics, and that epigenetic studies on atherosclerosis constitute a hot new area. In our study, we used bibliographic coupling analysis to establish similarity relationships between publications in different countries, journals, and institutions. These data indicated that  network . From th network . Based oThe visualization diagram is similar to the co-occurrence diagram, but the items are colored differently . This efOur studies have evaluated the trends and current status of atherosclerosis research in the area of epigenetics through bibliometric and visual analysis, the results of which also have some limitations. Although we also searched the keywords related to epigenetic modification repeatedly, we still could not avoid missing relevant articles. In addition, some new, high-quality publications may not receive attention because of their low citation frequency. These problems are the limitations of this article. Researchers need to pay greater attention to the latest published research in related fields, in order to more accurately predict the most important research trends in this field.Although considerable evidence has accumulated demonstrating how epigenetic modification plays an important role in atherosclerosis, more specific research still needs to be explored by scientists. The results of this study summarized the research status of epigenetic modifications in atherosclerosis, and predicted the future research trends in this field. An in-depth study of this field will ensure that we have a more accurate understanding of atherosclerotic disease and provide clear directions for clinical research. The bibliometric data show that atherosclerosis is developing rapidly with the study of DNA methylation, which is currently a hot research area that should be taking its place alongside the previous emphasis on lncRNA studies in atherosclerosis in the field of epigenetics.