Modelling and optimization analysis of a novel hollow flexible-filler-based bulk thermoelectric generator for human body sensor

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 study, 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 longitudinal and transverse hollow structures on maximum output power and corresponding optimal fill factor of the flexible TEG, and to reveal impact of key geometrical and physical parameters on design optimization of the 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; (4) the transverse-hollow structure combined with both-sides high-thermal-conductivity layers can increase output power up to 137.34 μWcm⁻². Such design of hollow PDMS filler could open a window of opportunity to the next generation efficient yet low-cost flexible TEG.