Nano-Engineered Versatile Janus Natural-Skin with Sandwich Structure for Wearable All-Season Personal Thermal Management

Abstract

Abstract Thermal management wearables have shown immense potential for various applications, such as bio-integrated electronics, multifunctional fabrics, thermoelectric devices, and clinical medicine. 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. In this study, we present a multifunctional nano-engineered Janus-type natural-skin (SHRC-skin), offering dual modes of solar heating and radiative cooling, along with additional capabilities such as flammability resistance, electromagnetic interference (EMI) shielding, and physiological signal monitoring achieved through the integration of traditional spray techniques and a phase conversion pathway, using natural-skin as a substrate, enabling year-round personal 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 of SHRC-skin 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 offers a range of additional wearable 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 can seamlessly transition between cooling and heating modes without additional energy input. This innovation holds great promise for all-season wearable thermal management, co-friendly travel, and energy-efficient building furnishings and opens up new possibilities for the development of wearable materials across various scenarios.