A kirigami-enabled electrochromic wearable variable-emittance 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, is 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 (WeaVE) device, 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 midinfrared thermal radiation heat loss of the human body. The kirigami design provides stretchability and conformal deformation under various modes and exhibits excellent mechanical stability after 1,000 cycles. 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 nonvolatile 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.

Sonochemical Coating of Textiles with Zinc Oxide: Robust, Silver-Seeded Growth on Cotton for Effective UV Shielding

“…Furthermore, the marginal deviation of coated substrate trace profiles from the uncoated material indicate that coatings are thin enough to only accentuate substrate properties rather than introduce their own. Although only marginal differences were observed, such capacities could potentially be meaningful long-term in wearable technologies . An enhanced reflectivity coupled to a high IR-emissivity on the outer surface of a textile could passively modulate the thermal comfort of wearables, e.g., radiative heat dissipation for more effective bodily cooling …”

“…Although only marginal differences were observed, such capacities could potentially be meaningful long-term in wearable technologies. 109 An enhanced reflectivity coupled to a high IRemissivity on the outer surface of a textile could passively modulate the thermal comfort of wearables, e.g., radiative heat dissipation for more effective bodily cooling. 110…”

Transparent grating-based metamaterials for dynamic infrared radiative regulation smart windows

“…Recently, dynamic infrared radiation (DIR) regulators have been proven to be an effective approach for achieving on-demand temperatures with ultra-low and even zero energy input. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] When hot, it functions as radiative cooling with high emissivity (e) and emits infrared (IR) radiation through the atmospheric transparent window (ATW, 8-13 mm) to the outer space (B3 K). When cold, it switches to a low e state and suppresses radiative heat loss.…”

Solution-Processed Metallic Nanowire Network for Wearable Transparent Thermal Radiation Shield

“…In addition to mid-IR transparency, solution-processed SEBS is highly stretchable and flexible, capable of taking any form. Its mechanical and optical properties are dictated by the polymer chain composition in which polybutylene and polyethylene groups contribute to the elasticity and mid-IR transparency of SEBS, respectively. − The physical cross-links of styrene groups are rigid, and the benzene ring results in large intrinsic mid-IR absorption coefficients. Therefore, a low content of polystyrene in SEBS is required.…”