AVS 66th International Symposium & Exhibition
    Electronic Materials and Photonics Division Thursday Sessions
       Session EM-ThP

Paper EM-ThP9
Biomimetic Electrospun Polyethylene Fabrics for Effective Radiative Cooling Under Sunlight

Thursday, October 24, 2019, 6:30 pm, Room Union Station B

Session: Electronic Materials and Photonics Poster Session
Presenter: Bokyung Park, University of New Mexico
Authors: B.K. Park, University of New Mexico
S.M. Han, University of New Mexico
S.E. Han, University of New Mexico
Correspondent: Click to Email
Clothing fabrics normally show high absorptivity for the mid-infrared radiation from human body. This high absorptivity, compared to transparency in the same spectral region, makes heat removal from the body relatively inefficient in hot weather conditions. In addition, the microstructures of typical fabrics are far from optimum for effective light scattering in the visible range, and the absorbed sunlight can significantly heat up the skin under the fabric. In this work, we borrow our inspiration from nature to optimize the fabric design. Biological species, such as white beetles, ingeniously regulate their body temperature using their scales. These scales consist of anisotropic fibrillar network structures to achieve extraordinary light scattering that is far superior to man-made optical diffusers. Based on the random photonic structures found in beetle scales, we have electrospun biomimetic fabrics using polyethylene, which is minimally absorptive in the mid-infrared range. By manipulating the fabric microstructures (e.g., anisotropy, porosity, and fibril diameter), we were able to increase the sunlight scattering strength. Optical scattering strength of our fabrics was characterized, using the optical diffusion model where the minimum photon transport mean free path – a length over which light propagation is no longer correlated to its original direction – represents the maximum scattering strength . We have discovered that the scattering strength can be enhanced by almost a factor of two by increasing the anisotropy of threads in the fabric. Our results suggest that fabrics for efficient heat removal from human body can be fabricated by simple electrospinning techniques that are low-cost, scalable, and high-throughput.