Distributed Energy Harvesting and Power Management Units for Self-Powered In-Fabric Sensing Networks

With the advancements in power and size reduction of integrated circuits, millimeter-scale self-powered systems can be seamlessly integrated into textiles or a single fiber strand, revolutionizing body sensor network applications. Energy harvesting and power management units (EHPMUs) face new design requirements for in-fabric systems including full autonomy, ultra-low quiescent power, high efficiency, and mm-scale footprint. Additionally, they must efficiently coordinate energy across distributed subsystems for enhanced system viability and scalability in a fiber or fabric network. This article examines current trends and innovative techniques for sub-uA EHPMUs. It presents two case studies of sub-uA distributed EHPMU designs: the first explores a switched-capacitor EHPMU featuring one-rail power sharing and cooperative dynamic-voltage-and-frequency-scaling; the second discusses a triple-input hybrid-inductor-capacitor multi-output EHPMU that offers improved efficiency, reduced size, multi-rail power sharing for heterogeneous fiber networks. We summarize the tradeoffs and key design considerations necessary for mm-scale EHPMUs designed for self-powered distributed fiber networks.