Wednesday 22 September 2021

Lupine Publishers| The Application Wearable Thermal Textile Technology in Thermal-Protection Applications

 Lupine Publishers| Journal of Textile and Fashion Designing


The needs for better thermal protection exist in various fields of our life, like the better thermal treatment, outside chill sports field and freezing working condition etc. However, the traditional passive thermal insulated clothing is insufficient, too blocky and heavy to constrain the movement of wearers and uncomforted to wear. Thus, an innovative light, flexible and active wearable thermal protection needs to be developed. This article reviews the relevant wearable thermal textile technology by utilizing the latest conductive textile materials in three developing levels: the fiber level, the yarn level and the fabric level, to provide more possibilities for new products development in various fields, which will facilitate the transfer from research achievement into mass production to realize its commercial benefits.

Keywords: Wearable technology; Thermal protection; Conductive textile; Silver-coated yarn


With the capability of the human to survive in various extreme environments is growing stronger and stronger, the desire to act and move freely in chill condition is growing as well. Although the surviving ability in the extremely cold condition has been confirmed, the free motion and activity in the chill environment and the thermal comfort is still a problem. In some circumstance, people need to work or do exercises in this severely cold condition so that they may sacrifice their thermal protection for a period to exchange for free motions and activities, because this thermal protection is too heavy, thick and blocky and it is also a kind of striction. In these circumstances, human is easy to be cold injured, such as frostnip, frostbite, trench foot, and even whole-body hypothermia etc. These cold injuries can occur on any body part, but tends to occur more on exposed areas such as the face and on the extremities, which have a high surface area to mass ratio and are also more often exposed to conductive heat loss. Some cold injuries are permanent and incurable.

Meanwhile, although human can survive through the low temperature condition, thermal comfort is still a problem that the traditional passive thermal-insulate clothing protection, which is thick and in blocky multi-layer structure, to prevent the heat dissipation to the environment as less as possible. In this circumstance, the heat energy source is only the human body itself. While in these extreme condition, the tradition passive thermal protection is insufficient. Further, this bulky and massive multilayer structure constrains the free movement of human beings, especially when human doing exercises and conducting works in chill winter outside trials.

Typically, the applicators involve relatively thick bulky compresses which do not conform closely to the contour of the body. Failure of the compress to conform closely and to retain close contact once positioned, results in irregular heating of the ski area. This problem often results in irregular or non-uniform healing of the skin, swelling, and the like. Further, due to its passive working-machinimas, this protection is far insufficient to maintain the thermal comfort of wearers in extreme condition, especially for the children and the elderly groups. Thus, an innovative flexural wearable active thermal technology is under research [1-3].

On the other hand, wearable smart textile is a new technology emerged two decades ago. After 20-year continuous developing, this technology already expends its applications into different fields, such as fashion, home textile, medicine, sports, military etc. It integrates flexible conductive materials to form complete electric circuit or functional e-components and connected to external circuit to achieve designed responsive functions towards outside stimulus or to enlarge the human themselves capability to against outside the environment. Currently, textiles are transcending their traditional functions and embrace various new possibilities to fulfill new roles in innovative functional exploration. Fibers are dramatically transforming the world and environment and as they do so, they are also inspiring radical new visions for the future.

In this way, thanks to the fast-growing wearable smart textile technology, conductive textiles with various electric resistant properties, can be applied for developing the proposed light, flexible active thermal-protective clothing products, through different fabricating methodologies to integrate these conductive textile materials together with different areas with different electric resistances so that following the Joule’s law, the target positions in a conductive fabric will enable to heat up actively when certain electric energy provided. This active thermal textile can be widely applied in the fields of professional and protective thermal wear, fashion, sport and well-being, home interiors, automotive, construction, medical and health care etc. Especially the fields, sports and medicine, are the two main drivers for further growth, because the attitude shift of our main consumption power that everybody is towards to pursuing for a healthy life manner, and the social aging problem is becoming more and more severe, the market potential is unpredictable [4-7].

The Thermal-protection in Various Scenarios

Scenario I-Thermal Treatment

Thermal treatment, or the manipulation of body or tissue temperature for the treatment of disease, can be traced back to the earliest practice of medicine. Cultures from around the world can point to ancient uses of hot therapy for specific medical applications, even including cancer. Today there are a growing number of clinical applications of thermal therapy that benefit patients with pain-relief, a variety of diseases and heat-activated drug delivery. In order to deliver a better therapy effects in a constant period, the thermal functional textile is required to closely fit with the body curve and contact the target skin position with large area and distribute the heat energy evenly in case any overheating occurs. Further, this technology can be extended to other fields, to offer this treatment all the time. It can integrate with fashion and textile, transportation and home textile, such as smart thermal mattress, sheets, pillowcases etc. to offer an active thermal comfort or thermal treatment to achieve better fatiguerelief and pain-relief effects. Especially, in the scene of home textile, through this next-to-skin technology, electric energy consumption can be significantly saved, compared to the traditional air-condition controlling manner [8-12].

Scenario II-Chilling Sports Field

Driven by the public pursuit for a healthy modern lifestyle and a perfect body figure, an upsurge of physical training and fitness is sweeping the entire world that everyone, not only professional athletes anymore, is taking exercise all the year around, even in the chill winter outside fields. This trend also boosts the consumption of thermal-protective sportswear recently. When the environmental temperature drops below 5ÂșC, it is already dangerous to conduct outdoor exercises that cold injuries may occur, especially when taking wind this factor into consideration. The relationship among the health risk, the tense of wind, the environmental temperature and the time of human subject exposure in the outdoor, is well studied and listed in the Figure 1. It shows that in the condition where the temperature under 40°F (5 °C) and the wind intense than 5mph/h, and the exposure time exceeds 30 min, there is a high risk to get cold injuries [13,14].

Figure 1: Wind Chill Temperature Index in Fahrenheit [14].* Wind Chill Temperature is only defined for temperatures at or below 50°F and wind speeds above 3 mph. Assumes no impact from the sun, i.e., clear night sky. Frostbite times are for exposed facial skin.

Thus, sufficient thermal protection against the chill condition is critical both for elite athletes and common sports consumers. For elite athletes, injuries may lead to missing the whole season, which also means losing sponsor deals and possible prize money. For common sports consumers, injuries may cause, for example, sick leaves from work, monetary losses both for the society and the individual. Injuries can also cause mental problems, especially for elite athletes, whose career depends on their bodies and its functioning. Injuries also may harm the physical progress, especially on young athletes, who develop quickly and might fall behind because of the cold injuries [15].

However, facing this high injury risk, the only current solution is to wear multi layers of clothing, which is heavy and blocky in the end. The cumbersome and multilayer-structure cloth of such clothing restricts physical motions and normal consumers will feel more exhausted, which makes it impractical. It is critical that designers understand the movement needs of individuals who will wear these thermal protections. Movement involves time, energy and space. Among these three elements, they need to rank after their importance by gathering realistic information from the practices. Additionally, it is suggested to take off the out layer after excises and starting to sweat out. However, how to deal with the taken-off clothing will be a problem. Carry them around and do strenuous exercises simultaneously? Of course, it is a distraction from the exercises. Therefore, the proposed wearable thermal textile can act as the second layer of sports skin to against the chill weather intelligently [14].

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