: Essential Energy Buffer-release Mechanisms and Intermittent Operations Toward Battery-free IoT Applications

Energy Harvesting (EH) technology is designed to capture ambient energy from various physical sources. While the available ambient energy is often small, it offers the convenience of onsite power generation by drawing energy from local sources, addressing the growing demand for long-lasting, extensively deployed, and maintenance-free Internet of Things (IoT) systems. EH is one of the most promising solutions for enabling battery-free IoT applications. In this talk, we begin by reviewing the evolution of EH technology over the past two decades, highlighting the contributions from various engineering disciplines. We will focus on the crucial roles of renewable sources, circuits, and systems in advancing EH. Special attention will be given to the energy buffer-release mechanism (EBRM) and intermittent operation, which are identified as essential elements for the practical realization of motion-powered IoT devices. We will explain how specifying energy and power criteria for the buffer and release processes ensures reliable IoT operation. Using recent designs from the speaker’s research group as examples, we will provide a detailed analysis of different forms of EBRM and intermittency in the context of motion-powered IoT systems. To conclude the talk, live demonstrations of motion-powered and light-powered wireless devices will be presented, followed by a discussion of the challenges and opportunities in advancing battery-free IoT systems.