Design and Fabrication of Flexible Thermoelectric String-Based Fabrics

Abstract

Flexible thermoelectric(TE) materials that convert heat into electricity have been widely used in wearable electronics and other flexible devices. In this work, inorganic TE pillars were combined with thermoplastic polyurethane(TPU) to assemble a flexible string-shaped TE generator(TEG) for the fabrication of the thermoelectric fabric(TEF). Moreover, finite element analysis(FEA) was used to optimize the dimensions of the TE string and evaluate its performance. The FEA results showed that the inter-pillar spacing significantly affected the temperature difference, the output voltage and the internal resistance. A maximum power density of 3.43 μW/cm²(temperate gradient ΔT=10.5 K) was achieved by the TE string with a diameter of 3.5 mm and an inter-pillar spacing of 2 mm. However, under the experimental condition, the achievable power density of the fabricated three-dimensional(3D) TEF was limited to 29% of the simulation result because of the inclination of the TE string within the fabric concerning heat plate contact and copper wire-TE pillar connections. The actual TE string also demonstrated high flexibility and stable mechanical properties after 450 bending cycles. Thus, the study would provide a foundation for future research in developing more efficient TEFs to offer a comfortable and conformable option for wearable energy harvesting applications.

Keywords

thermoelectric fabric(TEF) / thermoelectric(TE) pillar / thermoplastic polyurethane(TPU) / finite element analysis(FEA)

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Funding

National Natural Science Foundation of China(51973034)

Natural Science Foundation of Shanghai, China(23ZR1402500)

Fundamental Research Funds for the Central Universities, China(2232022G01)

Fundamental Research Funds for the Central Universities, China(19D110106)