Research ArticleAPPLIED SCIENCES AND ENGINEERING

A dual-mode textile for human body radiative heating and cooling

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Science Advances  10 Nov 2017:
Vol. 3, no. 11, e1700895
DOI: 10.1126/sciadv.1700895
  • Fig. 1 Schematic of dual-mode textile.

    (A) Traditional textiles only have single emissivity, so the radiation heat transfer coefficient is fixed. (B) For a bilayer thermal emitter embedded in the IR-transparent nanoPE, when the high-emissivity layer faces outside and the nanoPE between the skin and the emitter is thin, the high emissivity and high emitter temperature results in large heat transfer coefficient, so the textile is in cooling mode. (C) The textile is flipped, and the low emissivity and low emitter temperature cause the heat transfer coefficient to decrease. The textile now works in heating mode.

  • Fig. 2 Dual-mode textile morphology and emissivity characterization.

    (A) Image of a carbon-coated nanoPE, the high-emissivity layer. (B) SEM image of carbon coating reveals its rough and porous structure, which is advantageous for increasing the emissivity. (C) Image of a copper-coated nanoPE, the low-emissivity layer. (D) SEM image of copper coating shows that the surface is optically smooth for mid-IR. The nanopores remain open for air and vapor permeability. (E) Layered structure of the dual-mode textile. Note that the nanoPE on the side of carbon is thicker than the copper side. Note that all the materials are porous to allow air and vapor breathability. (F) Emissivities of carbon and copper coating, as measured by FTIR equipped with a diffuse gold integrating sphere.

  • Fig. 3 Thermal measurement of the dual-mode textile.

    (A) Steady-state artificial skin temperature of various conditions: bare skin, traditional textile, cooling mode textile, and heating mode textile. The cooling and heating mode is the same piece of sample (#2) with different sides facing out, and the resulting artificial skin temperature is different. (B) Four dual-mode textiles with eight different top-layer emissivities result in different skin temperatures. The skin temperature is inversely related to the top-layer emissivity, which indicates the importance of radiation heat transfer toward the environment. (C) The temperature difference caused by mode switching is positively related to the emissivity difference between the two layers. Carbon-only and copper-only samples are also measured to verify that the dual modality does not depend on the absolute value of emissivity but on its difference. (D) Calculated artificial skin temperature as the function of top- and bottom-layer emissivities. The maximal temperature difference generated by the dual-mode textile occurs when Δε = 0.8, which are marked with the star symbols.

  • Fig. 4 Expansion of thermal comfort zone by the dual-mode textile.

    (A) Thermal comfort zone of bare skin, traditional textile, and dual-mode textile. The artificial skin temperature is between 32° and 36°C. (B) Real-time thermal measurements of dual-mode and traditional textiles under varying ambient temperatures. By using cooling mode at high ambient temperature and heating mode at low temperature, the artificial skin temperature stays within 32° to 36°C even if the ambient temperature changes between 16° and 25°C. In contrast, the traditional textile can only follow the trend of ambient temperature variation and result in thermal discomfort during the ambient temperature sweep. The error bars represent the SD of three measurements.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/11/e1700895/DC1

    Supplementary Text

    fig. S1. Thermal circuit model of textiles.

    fig. S2. Direct copper deposition on carbon/nanoPE.

    fig. S3. Schematic of thermal measurement apparatus.

    fig. S4. Sweating hotplate thermal measurement.

    fig. S5. Emissivities of samples #1 to #4 used in the experiments.

    fig. S6. Complete thermal measurement and weighted average emissivity of various samples.

    fig. S7. Wearability tests of dual-mode textile, T-shirt, and sweatshirt.

    fig. S8. Performance durability of dual-mode textile against wash cycles.

    fig. S9. Comparison between IR-transparent and IR-opaque dual-mode textiles.

    fig. S10. Emissivities of alternative materials for bilayer emitters.

    fig. S11. Calculated comfortable ambient temperature as the function of top- and bottom-layer emissivities at Tskin = 34°C.

    fig. S12. Guarded hotplate setup for thermal conductivity measurement.

    fig. S13. Emissivity spectrum of the traditional textile.

    fig. S14. Weighted average emissivities of heating mode, cooling mode, and traditional textiles as a function of temperature.

    fig. S15. Overlay of thermal measurement data on the numerical fitting result.

    fig. S16. Measurement of specular, diffuse, and angle-dependent emissivities.

    table S1. Thickness of dual-mode textiles.

    table S2. Numerically fitted values of heat transfer components.

    table S3. Thermal properties of the dual-mode and the traditional textiles measured by guarded hotplate method.

    References (35, 36)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • fig. S1. Thermal circuit model of textiles.
    • fig. S2. Direct copper deposition on carbon/nanoPE.
    • fig. S3. Schematic of thermal measurement apparatus.
    • fig. S4. Sweating hotplate thermal measurement.
    • fig. S5. Emissivities of samples #1 to #4 used in the experiments.
    • fig. S6. Complete thermal measurement and weighted average emissivity of various samples.
    • fig. S7. Wearability tests of dual-mode textile, T-shirt, and sweatshirt.
    • fig. S8. Performance durability of dual-mode textile against wash cycles.
    • fig. S9. Comparison between IR-transparent and IR-opaque dual-mode textiles.
    • fig. S10. Emissivities of alternative materials for bilayer emitters.
    • fig. S11. Calculated comfortable ambient temperature as the function of top- and bottom-layer emissivities at Tskin = 34°C.
    • fig. S12. Guarded hotplate setup for thermal conductivity measurement.
    • fig. S13. Emissivity spectrum of the traditional textile.
    • fig. S14. Weighted average emissivities of heating mode, cooling mode, and traditional textiles as a function of temperature.
    • fig. S15. Overlay of thermal measurement data on the numerical fitting result.
    • fig. S16. Measurement of specular, diffuse, and angle-dependent emissivities.
    • table S1. Thickness of dual-mode textiles.
    • table S2. Numerically fitted values of heat transfer components.
    • table S3. Thermal properties of the dual-mode and the traditional textiles measured by guarded hotplate method.
    • References (35, 36)

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