Metafabrics for Thermoregulation and Energy-Harvesting Applications

Abstract

Metafabrics are textiles with engineered constituent elements, possessing peculiar properties, which cannot be achieved with conventional fabrics. Fabric structures are formed of fibers bundled up and twisted into yarns. Yarns are then intertwined or bond closely together to shape the fabric structure. Engineering the textiles can be performed by utilizing novel materials for constitutive fibers and also manipulating the size and structure of fibers and yarns. In this paper, we employ a powerful and realistic model to design and investigate metafabrics for unique applications in personal thermal cooling, thermal insulation, and thermoregualation by means of engineering fabric building blocks. We provide physical insights into the behavior of the so-called infrared-transparent visible-opaque fabrics (ITVOFs), study the effect of using metallic-coated fibers on the thermal insulation functionality of a breathable textile, and also propose an alternative form for phase-change fabrics (PCFs) consisting of core–shell fibers with phase-change material (PCM) cores. Also, we develop a robust design principle to transform fabrics into fully functional devices, guiding, and manipulating thermal radiation through graded yarns with core–shell fibers. In particular, a focusing metafabric is designed to concentrate the thermal radiation into localized high energy spots. We integrate this focusing device into a multilayer technical platform to harvest the thermal energy from human body through effectively coupling the thermal radiation into a layer of IR-detector material. A considerable enhancement ratio of 7.46 is achieved in the current density generation through the metafabric.

Emerging Materials and Strategies for Personal Thermal Management

“…Besides, the fiber cross section also influences the thermal radiation. [97,98] It is found that the textile woven with triangular polyamide (PA) fiber achieved a remarkable emissivity of 91.85%, better than the circular fiber with emissivity of 81.72%. This is because that the triangular fibers have different orientations inside a single yarn, benefiting for the absorption (and emission) of incident IR radiation from different directions with a higher efficiency.…”

Time-varying metamaterials based on graphene-wrapped microwires: Modeling and potential applications

“…The method has evolved quite dramatically ever since and has been adapted to solve several problems involving periodic and aperiodic arrangements of cylindrical objects [46][47][48][49] . In particular, the authors have extended the method to take into account for multiple scattering between cylinders and layered substrates 50 as well as crossed configurations of cylinders 51,52 . Here, we develop a novel semi-analytical framework by extending the T-matrix formulation to solve electromagnetic scattering from substrate-supported periodic and aperiodic arrays of cylindrical structures wrapped by time-varying graphene layers.…”

“…In the non-resonant Mie scattering region (effective medium regime) associated with deeply subwavelength microwires, they can be used to realize an effective refractive index by virtue of internal homogenization 3,15,52 . As such, time-modulated graphene-wrapped microwires can be used for realization of space-time gradient metamaterials and photonic crystals 69 .…”

“…We consider a TM-polarized incidence. The effective permittivity of the graphene-wrapped microwire is obtained as a function of Fermi energy level of graphene for a TM-polarized plane wave using a parameter retrieval technique 3,52 and is shown in Fig. 9(a).…”

Polymer photonic crystal membrane for thermo-regulating textile

“…The heating production is then generated from the human body radiation supplementary reflection that can even being increased by adding Joule heating to complement the passive insulation. For cooling purpose, recent papers have proposed different fibers [15][16][17][18] or membranes [19][20][21] fabrics to increase IR transparency. In the fiber configuration, Tong et al 15 proposed an infrared-transparent-visible-opaque-fabric (ITVOF) made of synthetic polymer fibers with intrinsically low IR absorbance and structured fibers to maximize IR transparency and visible opaqueness.…”