Nano-engineered versatile Janus natural-skin with sandwich structure for wearable all-season personal thermal management

Abstract

Thermal management wearables hold significant promise for various applications, such as bio-integrated electronics, multifunctional fabrics, thermoelectric devices, etc. Given the complex and volatile external environmental conditions they may encounter, thermal management wearables should possess versatile and comprehensive auxiliary functions to enable cutting-edge advanced applications. Herein, we present a multifunctional nano-engineered Janus-type natural-skin (SHRC-skin) offering dual-modes of solar heating and radiative cooling. Additionally, the SHRC-skin integrated functionalities like flammability resistance, electromagnetic interference (EMI) shielding, and physiological signal monitoring achieved through the integration of traditional spray techniques and a phase-conversion pathway on natural-skin as a substrate, SHRC-skin enabled all-season thermal management. The radiative cooling side of the SHRC-skin incorporates a CA/Mg11(HPO3)8(OH)6 composite coating with an irregular porous structure, while the solar heating side consists of multi-walled carbon nanotubes (MWCNT) with a rough structure. The radiative cooling layer exhibited a solar reflectance of ∼90.13 % and a mid-infrared emittance of ∼87.6 %, whereas the heating layer demonstrated a solar absorptance of ∼89 %. These attributes translated to excellent thermal management performance in outdoor-tests. Furthermore, SHRC-skin offered extensive additional functionalities, including exceptional asymmetric wetting, flame retardancy, electrical conductivity, Joule heating, electromagnetic shielding, and physiological signal monitoring. This versatility significantly enhances SHRC-skin's adaptability to complex and diverse environments. In summary, the multifunctional SHRC-skin seamlessly transitions between cooling and heating modes without additional energy input. This innovation holds great promise for all-season wearable thermal management, environmentally friendly travel, and energy-efficient building furnishings, and opens new possibilities for the development of wearable materials across various scenarios.