Design Strategies for High-Performance Piezoelectric Energy Harvesting Devices

Smart sensor networks play important roles in structural monitoring, health diagnosis, and data transmission. Given their extensive distributed energy requirements, piezoelectric energy harvesting, which aims to convert mechanical vibrational energy into electrical power, can serve as a viable alternative or supplement to power supplies owing to its compact size, high power density, and excellent stability. Piezoelectric energy harvesting involves three key components: piezoelectric materials responsible for mechanical-to-electrical energy conversion, mechanical structures enabling mechanical-to-mechanical energy transmission, and power-management systems used to efficiently extract electrical energy. For electromechanical conversion, state-of-the-art piezoelectric materials, including crystals, ceramics, polymers, and composites, are analyzed. Regarding mechanical energy transmission, the focus is on methodologies to achieve high power output, wide bandwidth, and multi-directional vibration capability. Several widely adopted electrical circuits are comprehensively reviewed in terms of power management. From an application perspective, practical energy harvesters are categorized into magneto-mechano-electric, fluid-based, biomechanical, and ultrasound-induced types. Additionally, future theoretical and practical challenges in piezoelectric energy harvesting are discussed.