With the development of the Internet of Things (IoT) and biomedical technologies, the utilization of wearable devices has become an emerging trend, attracting attention to the powering solutions for these devices. Thermoelectric energy harvesting (TEH) is suitable for converting the temperature difference in the ambient environment to power wearable devices and IoT sensors. However, the DC voltage converted by the thermoelectric generator (TEG) still requires an energy harvesting interface, normally a DC-DC interface to provide the regulated power to the load. Consequently, the features of the TEG impose challenges to the implementation of the DC-DC interface. Due to the temperature dependency of the TEG, the DC-DC interface applied to the TEH system should be able to cope with the dual-polarity input voltage and be capable of achieving a high power conversion efficiency for a wide range of voltage conversion ratios.