Smart piezoelectric energy harvesting: how topology-optimized cavities boost performance in BaTiO₃ multilayer structures

The escalating global energy demand and environmental challenges underscore the urgent need for efficient, sustainable energy-harvesting solutions. In this study, we present a lead-free multilayer piezoelectric energy harvester, termed Arcade Sensor A, fabricated from BaTiO 3 ceramics and incorporating topology-optimized arch-shaped cavities. This design enables enhanced mechanical-to-electrical energy conversion by promoting optimal stress distribution while reducing raw material usage by 72%. Through a synergistic approach combining finite element modeling and experimental validation using a bicycle-traffic simulation platform, the cavity-embedded structure achieved a power density of 0.51 µ W cm −3 (simulated) and 0.35 µ W cm −3 (experimental), outperforming both bulk and cavity-free multilayer counterparts despite its lower piezoelectric coefficient ( d 33 = 107 pC/N). This work bridges material innovation, structural optimization, and real-world application, offering a scalable and robust solution for smart infrastructure and self-powered sensor systems.