Research ArticleAPPLIED SCIENCES AND ENGINEERING

High-performance wearable thermoelectric generator with self-healing, recycling, and Lego-like reconfiguring capabilities

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Science Advances  10 Feb 2021:
Vol. 7, no. 7, eabe0586
DOI: 10.1126/sciadv.abe0586
  • Fig. 1 Design and fabrication of the TEG.

    (A) Schematic illustration of the design, fabrication process, and key characteristics, including self-healability, recyclability, and Lego-like reconfigurability. Optical images of the TEG when it is flat (B), bent (C), stretched (D), and worn on the finger (E). Photo credit: Yan Sun, University of Colorado Boulder.

  • Fig. 2 Output and endurance of TEGs.

    (A) Power generation (Pout) as a function of output voltage (Vload) at various temperature differences (ΔT), with the cold-side temperature (Tcold) kept at 20°C. The black points are measurement data. (B) Maximum power generation (Pmax) versus temperature difference. (C) Open-circuit voltage (Voc) versus temperature difference. The solid lines in (A) and (B) are fitting curves using parabolic functions. The solid line in (C) is a linear fitting curve. (D) One hundred–hour endurance test with the hot-side temperature (Thot) kept at 100°C. The cold side was natural convection, and the room temperature (Troom) was around 26°C. (E) Performance comparison between this TEG and other flexible TEGs reported in the literature (see the Supplementary Materials for details). Flexibility refers to the minimum bending radius of TEGs experimentally demonstrated in the literature.

  • Fig. 3 Wearable energy harvesting and mechanical properties of the TEG.

    (A) Optical and infrared (inset) images of a TEG attached on an arm. (B) Power generation (Pout) and output voltage (Vload) of the TEG with 112 thermoelectric legs on the human skin when the wearer was sitting and walking. The cold side was natural convection. Finite element method (FEM) simulated strain distribution contours in the TEG and TE legs (inset) when the TEG is bent to a radius of 3.5 mm (C) and stretched by 120% (D). (E) Relative electrical resistance change and power generation stability over 1000 bending cycles. The inset shows optical images of the TEG when it is flat and bent. The bending radius r = 3.5 mm, R0 is the original resistance, and ΔR is the change in resistance. (F) Relative electrical resistance change and power generation versus stretching ratio (ΔL/L0). For output power (Pout) measurements in (E) and (F), the hot-side temperature was kept at 41°C, the cold side was natural convection, and the room temperature was around 26°C. The inset in (F) shows optical images of a TEG during tension test, which is in series with a light-emitting diode (LED) and a 4-V DC source for visual demonstration (fig. S11). Photo credit: Yan Sun, University of Colorado Boulder.

  • Fig. 4 Self-healing, recycling, and Lego-like reconfiguration.

    (A) Schematic illustration of self-healing mechanism. (B) Optical images of the TEG in a self-healing test. The original TEG is flexible and in series with a LED and a 4-V DC source (left). When the liquid-metal electrical wiring and polyimine substrate are both cut broken, the LED turns off (top middle). When the two surfaces at the broken site are brought into contact, the liquid-metal electrical wiring heals immediately, leading to the LED to turn on (bottom middle). After 1.5 hours, the polyimine substrate completely heals and regains mechanical robustness (right). (C) Relative electrical resistance change (ΔR/R0) of a self-healed TEG versus stretching ratio. The inset shows optical images of the self-healed TEG during tension test. (D) Optical images of the TEG at different recycling steps. The new TEG is in series with a LED and a 4-V DC source (bottom left). (E) Power generation comparison between the old TEG and the recycled new TEG. (F) Lego-like reconfiguration of two separate TEGs (devices I and II) into a new functional TEG (device III). The new TEG (device III) is in series with a LED and a 4-V DC source (right). (G) Power generation comparison between TEG I, II, and III. Photo credit: Yan Sun, University of Colorado Boulder.

  • Fig. 5 Outdoor performance enhancement with wavelength-selective metamaterial films.

    (A) Schematic illustration of heat-transfer processes of TEGs with bare surface (top) and wavelength-selective surface (bottom) during the daytime and nighttime. Psolar and Patm are the solar irradiation power and atmospheric radiation power on the surface, respectively, Prad is the thermal radiation power from the surface, and Pnonrad is the nonradiative heat transfer (convection and conduction) between the surface and ambient. (B) Measured absorptivity/emissivity of the bare surface and wavelength-selective surface from 300 nm to 25 μm. The absorptivity/emissivity of the atmosphere (gray block) and power density of spectral solar irradiance [yellow block; air mass (AM), 1.5] are also included. Both bare surface and wavelength-selective surface have strong emission between 8 and 13 μm (atmospheric transmission window), indicating excellent radiative cooling performance. The bare surface has strong absorption at full solar spectrum (>0.87) and other infrared bands (>0.96), while the wavelength-selective surface has much weaker absorption at solar spectrum than at infrared bands. (C) Solar irradiance, outdoor temperature, and wind speed measured by a weather station from 13:00 to 18:00 (9 November 2019, Boulder, CO, USA). Total surface heat exchange (D), output voltage (E), and power generation (F) of the TEGs with bare surface and wavelength-selective surface at the cold side from 13:00 to 18:00.

Supplementary Materials

  • Supplementary Materials

    High-performance wearable thermoelectric generator with self-healing, recycling, and Lego-like reconfiguring capabilities

    Wei Ren, Yan Sun, Dongliang Zhao, Ablimit Aili, Shun Zhang, Chuanqian Shi, Jialun Zhang, Huiyuan Geng, Jie Zhang, Lixia Zhang, Jianliang Xiao, Ronggui Yang

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    The PDF file includes:

    • Notes S1 to S3
    • Figs. S1 to S19
    • Tables S1 and S2

    Other Supplementary Material for this manuscript includes the following:

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