Smart gating of the flexible Ag@CoxMo1-xP and rGO-loaded composite based personal thermal management device inspired by the neuroanatomic circuitry of endotherms

Abstract

Personal thermoregulation is a major goal in the development of smart, wearable devices, regardless of climate conditions, and can reduce the demand for power from external sources. An immense amount of energy is consumed for heating indoor environments in cold weather, while body heat is continually radiated into the surroundings. Maintaining comfortable personal thermal conditions while outdoors in the summer is also challenging. Here, we have developed a novel personal thermoregulatory (PTM) device inspired by the thermoregulation mechanism of endotherms. The PTM device features a smart heating/cooling mechanism that responds to changing climatic conditions. The devices were fabricated with woven Kevlar fiber (WKF) containing perpendicularly grown silver nanoparticle-decorated branched cobalt molybdenum phosphide nanowires (Ag@CoxMo1-xP). These fibers were spin-coated with reduced graphene oxide (rGO) dispersed in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) or PEDOT:PSS/poly(N-isopropylacrylamide) (PNIPAM). Ag@CoxMo1-xP coupled with rGO promoted efficient Joule heating, attaining 76 degrees C at 2.1 V, in WKF/ PEDOT:PSS. Ag@CoxMo1-xP incorporated into WKF/PEDOT:PSS showed higher infrared (IR) reflectance (97.9%) and thermal insulation (52.1%) than bare WKF/PEDOT:PSS. However, IR transmittance increased, and thermal insulation decreased, with increasing surrounding temperature when Ag@CoxMo1-xP were incorporated into a PNIPAM composite. All of the Ag@CoxMo1-xP and rGO-loaded composites exhibited remarkable durability, flexibility, and air permeability, with increased impact resistance (162.2%) and tensile strength (94.9%). The Ag@CoxMo1-xP device fabricated without PNIPAM functioned as a wearable heater and, when doped with PNIPAM, provided a passive heating/cooling effect depending on the environmental temperature. Thus, our PTM devices could help to mitigate the world energy crisis by helping the wearer maintain to a comfortable personal environment while minimizing household energy consumption.