Material Optimization for a High Power Thermoelectric Generator in Wearable Applications

Won Lee,Byung Cho,Hyeongdo Choi,Seongho Kim,Yong Kim,Gyusoup Lee,Garam Choi,Choong Kim,Hyo Kim

doi:10.3390/app7101015

Abstract

Thermoelectric power generation using human body heat can be applied to wearable sensors, and various applications are possible. Because the thermoelectric generator (TEG) is highly dependent on the thermoelectric material, research on improving the performance of the thermoelectric material has been conducted. Thus far, in developing thermoelectric materials, the researchers have focused on improving the figure of merit, ZT. For a TEG placed on the human body, however, the power density does not always increase as the material ZT increases. In this study, the material properties and ZT of P-type BiSbTe3 were simulated for carrier concentration ranging from 3 × 1017 to 3 × 1020 cm−3, and the power density of a TEG fabricated from the material dataset was calculated using a thermoelectric resistance model for human body application. The results revealed that the maximum ZT and the maximum power density were formed at different carrier concentrations. The material with maximum ZT showed 28.8% lower power density compared to the maximum obtainable power density. Further analysis confirmed that the mismatch in the optimum carrier concentration for the maximum ZT and maximum power density can be minimized when a material with lower thermal conductivity is used in a TEG. This study shows that the ZT enhancement of materials is not the highest priority in the production of a TEG for human body application, and material engineering to lower the thermal conductivity is required to reduce the optimum point mismatch problem.

Highlights

Thermoelectric generators (TEGs), which convert waste heat into electricity, are one of the most promising energy harvesting devices [1]
It was shown that low thermal conductivity is advantageous for energy harvesting on the human body while the ZT remains at the same value [20]
In order to understand the optimal engineering direction of the thermal conductivity, a device simulation to find the optimum point of the power density should be performed concurrently

Summary

Introduction

Thermoelectric generators (TEGs), which convert waste heat into electricity, are one of the most promising energy harvesting devices [1]. Thermoelectric power generation from human body heat is becoming a promising field as it can be applied to Internet of Things (IoT) and wearable electronics [2]. It has been reported that thermoelectric devices can generate around 30 μW/cm of power when they are attached to the human body [3], and that level of power can drive low-power chips such as sensors in wearable devices [4,5]. As higher power density generation is always desirable, various studies have been carried out to improve the device performance.

Methods

Results

Conclusion