Evaluation on the Power Generation Capacity of an Implantable Thermoelectric Generator Driven by Radioisotope Fuel

Abstract

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 such a method lies in its direct utilization of the temperature difference intrinsically existing throughout the whole biological body. Therefore, it can resolve the service life mismatch between the IMD and its battery. In order to promote the stability of the powergeneration capacity of the implanted TEG, this paper is dedicated to study a low cost and highly safe practical pattern of implanting a TEG driven by the radioisotope fuel into a human body. Recurring to the thermal energy releasing during disintegration of the radioactive isotope, it can guarantee a marked promotion in the temperature difference across the implanted TEG, consequently supplying enough power for the IMDs. A bioheat transfer model with or without a large vessel is established to characterize the feasibility and working performance of the method. The numerical simulation and parametric studies on tissue status, device properties, and environmental conditions revealed that, no matter in what conditions, the implanted TEG driven by the radioisotope fuel can always offer a much higher energy output than that provided by body heat alone. Meanwhile, in vivo/surrounding environment, isotope conditions, and intentional skin surface cooling also exhibit a direct influence on the temperature distribution of the implantable TEG and thus affect the working performance. Coordinating with the intentionally imposed cooling on the skin surface, the maximum TEG power can reach several mW, which is strong enough to meet the power consumption of the IMDs. These results were expected to be a valuable reference for designing an implantable TEG, which may actually be used in future clinics.