Modelling and Optimization Analysis of a Novel Hollow Flexible-Filler-Based Bulk Thermoelectric Generator for Human Body Sensor

Abstract

Thermoelectric generator (TEG) is a promising technology for self-powered wearable electronics and sensors. Usually, polydimethylsiloxane (PDMS) is selected as bulk thermoelectric gap filler to make the TEG flexible. However, PDMS has much higher thermal conductivity than air causing considerable thermal shortcut and efficiency degradation. In this work, a novel hollow PDMS-filler design is proposed to enhance the TEG performance. A well-validated three-dimensional thermal and electrical coupled model is developed to assess effects of hollow structures on maximum output power and optimal fill factor of the flexible TEG. Results show that, (1) as height of the hollow structure increases, the output power increases linearly, while the optimal fill factor decreases sharply; (2) the transverse-hollow structure is more effective than the longitudinal-hollow structure to create higher power; (3) the transverse-hollow structure can approximately double the output power while halve the optimal fill factor. The design of transverse-hollow PDMS filler, therefore, is an effective technique to enhance the output power and reduce the fabrication cost of flexible TEGs. In addition, effects of key geometric and physical parameters such as TE leg length and cross-sectional area, thermal conductivity of PDMS, and cold-side heat transfer coefficient on design optimization of the TEG are revealed.

Keywords: Flexible thermoelectric generator, Polydimethylsiloxane, Hollow structure, Multiphysics modelling, Optimized designs.