Research on Design and Performance Optimization of Flexible Thermoelectric Thin Film Wearable Device for Human Thermal Energy Collection

Abstract

In order to solve the problems of limited battery life and environmental pollution caused by the dependence of wearable devices on lithium-ion batteries, this study focuses on the efficient collection of human thermal energy, and proposes a flexible stretchable array design based on gradient nanostructure thermoelectric materials, which breaks through the bottleneck of the existing technology through the collaborative optimization of the whole chain of "material-structure-system". On the material level, the Bi₂Te₃/Sb₂Te₃ quantum dot superlattice thin film is constructed, and the Seebeck coefficient is increased to 258±8μV/k, the electrical conductivity is increased to 1250±60S/cm, the thermal conductivity is reduced to 0.9±0.05 W/MK, and the comprehensive thermoelectric figure of merit (ZT) is 1.32, which is nearly double that of the traditional thin film. At the structural level, a 3D spiral thermoelectric unit is designed to increase the effective thermoelectric arm length by three times (about 600 μ m) compared to a planar structure, reduce interface thermal resistance by 60% (as low as 88 ± 5K · cm ²/W), and significantly optimize heat transfer efficiency. At the system level, phase change materials (PCM) are integrated to smooth out temperature fluctuations caused by human movement (<1 ℃), and combined with flexible perovskite photovoltaic units to achieve thermoelectric photovoltaic synergistic collection. The test results show that the device has a maximum power density of 15.2 μ W/cm² at a temperature difference of 5 ℃, which is 2 orders of magnitude higher than traditional flexible devices; After 10000 bending cycles (radius 5mm) and 30% stretching cycles, the resistance change rate is less than 3%, the power attenuation rate is less than 5%, and it meets the ISO 10993 biocompatibility standard (cell survival rate>90%, skin irritation index 0.2). This study provides a new technological path for self powered wearable devices that combines efficiency, flexibility, and biocompatibility.