Design trends of low power thermal energy harvesting power management units

Thermal energy harvesting has gained attention in the last decade due to its promising possibilities in powering pervasive wireless sensor nodes, facilitating autonomous wireless sensor networks (WSN) for wide range of IoT (Internet of Things) applications. Thermal energy scavenging from waste heat can enable implementation of battery-less, zero-maintenance, place-and-forget electronic systems. Scavenging energy from the temperature difference between human body heat and ambiance is an attractive solution for powering wearables for continuous health monitoring, biomedical sensing and body area sensor networks (BASN). The low energy efficiency and low voltage output of the thermo-electric generators (TEG) pose challenges to the deployment of industry ready powering systems. These issues become more relentless, for energy scavenging from body heat using micro-TEGs, owing to the low temperature difference available. The low voltages generated by the transducers are ineffectual unless a power management converter system is incorporated to boost and regulate the voltage available to the load. The inherent inconsistent nature of the energy available from the ambience is yet another challenge to deal with. Hence, Energy Harvesting Power Management Units (EHPMU) are highly essential to integrate TEGs with commercial load systems. This chapter presents the challenges and recent trends in the design of integrated EHPMUs in CMOS (complementary metal-oxide-semiconductor) technology for harvesting thermal energy from low temperature difference environments. The state-of-the-art converter topologies in EHPMUs and recent trends in design of energy harvesting Integrated Circuits (IC) design are also discussed. © 2019 Nova Science Publishers, Inc