Energy harvesting based on corner states with tunable elastic higher-order topological insulators

In recent years, the devices for piezoelectric energy harvesting based on phononic crystals have gained increasing prominence in the field of acoustic/elastic wave energy harvesting, owing to their ability to concentrate acoustic/elastic waves and vibration energy at specific locations. However, these devices face challenges related to robustness and efficiency degradation caused by structural defects or disturbances. To tackle this challenge, we introduce a novel piezoelectric energy harvesting utilizing elastic higher-order topological insulators in this study. Numerical modeling and experimental data collectively reveal that the attachment of a piezoelectric patch at the corner points effectively harvests elastic wave energy. Moreover, leveraging the topological protection effect, the device maintains excellent elastic wave energy harvesting capability even in the presence of point defects. Additionally, we introduce magnetostrictive materials for tuning the frequencies of corner states under different magnetic fields through numerical calculations. The results indicate that by applying various magnetic fields, it is possible to tune the corner states to match desired operating frequencies. This research presents valuable perspectives and actionable guidelines to inform the design of innovative elastic wave energy harvesting systems.