Suitability of a thermoelectric power generator for implantable medical electronic devices

Embedding a thermoelectric generator ( TEG) in a biological body is a promising way to supply electronic power in the long term for an implantable medical device ( IMD). The unique merit of this method lies in its direct utilization of the temperature difference intrinsically existing throughout the whole biological body. However, little is known about the practicability of such a power generation strategy up to now. This paper attempts to evaluate the energy generation capacity of an implanted TEG subject to various physiological or environmental thermal conditions. Through theoretical analysis, it was found that the highest temperature gradient occurs near the skin surface of the human body, which suggested a candidate site for implanting and positioning the TEG. In addition, numerical simulations were performed on three- dimensional bioheat transfer problems in human bodies embedded with TEGs at different implantation depths and configurations. To further enhance energy generation of an implanted TEG, several external technical approaches by intentionally cooling or heating the skin surface were proposed and evaluated. Conceptual experiments either in vitro or in vivo were implemented to preliminarily test the theoretical predictions. Given the fact that an IMD generally require very little working energy, the TEG could serve well as a potential long- term energy supplier for such medical practices.