A Kirigami-enabled Electrochromic Wearable Variable Emittance (WeaVE) Device for Energy-Efficient Adaptive Personal Thermoregulation

Abstract

For centuries, people have put effort to improve the thermal performance of clothing to adapt to varying temperatures. However, most clothing we wear today only offers a single-mode insulation. The adoption of active thermal management devices, such as resistive heaters, Peltier coolers, and water recirculation are limited by their excessive energy consumption and form factor for long-term, continuous, and personalized thermal comfort. In this paper, we developed a wearable variable-emittance device (WeaVE), enabling the tunable radiative heat transfer coefficient to fill the missing gap between thermoregulation energy efficiency and controllability. WeaVE is an electrically driven, kirigami-enabled electrochromic thin-film device that can effectively tune the mid-infrared thermal radiation heat loss of the human body. The kirigami designs provide stretchability and conformal deformation attached to the human body surface, and the electronic control enables programmable personalized thermoregulation. With less than 5.58 mJ/cm2 energy input per switching, WeaVE provides 4.9°C expansion of the thermal comfort zone, which is equivalent to a continuous power input of 33.9 W/m2. This non-volatile characteristic substantially decreases the required energy while maintaining the on-demand controllability, thereby providing vast opportunities for the next generation of smart personal thermal managing fabrics and wearable technologies.

Stay healthy under global warming: A review of wearable technology for thermoregulation

“…However, it cannot be controlled on demand, which restricts its capabilities in personalized thermoregulation. Instead, active‐dynamic that integrates wearable sensors and dynamic tunable thermoregulation devices is the most promising method to enable personalized health‐oriented thermoregulation 24,25 . It allows individuals to maintain customized thermal comfort under varying metabolic and environmental conditions in an autonomous manner.…”

“…In this regard, the criteria of health‐oriented thermoregulation extend beyond static cooling function towards dynamic controllability and various sensors that can complete the feedback loop and maintain thermal comfort in an autonomous and personalizable manner. In 2022, Chen et al 24 developed a wearable variable‐emittance device (WeaVE), which is a layered semi‐solid electrochemical cell with electrodeposited polyaniline (PANI) on electrodes. As the carrier concentration and optoelectrical property of PANI can be varied by switching continuously and reversibly between oxidation/reduction states, WeaVE is able to realize mid‐IR electrochromism, which can dynamically control the emissivity to stabilize the radiative heat loss under varying ambient temperature.…”

“…Instead, active-dynamic that integrates wearable sensors and dynamic tunable thermoregulation devices is the most promising method to enable personalized health-oriented thermoregulation. 24,25 It allows individuals to maintain customized thermal comfort under varying metabolic and environmental conditions in an autonomous manner. Active cooling thermoregulation systems that rely on external work to enhance heat transfer, such as thermoelectric device (TED), [26][27][28] liquid cooling circulation, 29 and air ventilation, 30,31 can successfully deliver a higher cooling power.…”

“…Actively adaptive, which integrates wearable sensors and dynamic thermoregulation devices into a feedback loop, is considered the most promising method for personalized health-oriented thermoregulation, as it allows individuals to maintain their thermal comfort in different metabolic and environmental conditions autonomously. 24 Active thermoregulation that normally delivers a higher cooling power can work as first-aid equipment for extreme weather conditions or healththreatening emergencies with a strong demand for cooling. Reproduced with permission.…”