Vibration modes switching induced triple frequency up-converting and the application in wireless sensing

This research introduces a piezoelectric energy harvesting (PEH) system equipped with stoppers to achieve broadband triple-frequency up-converting energy harvesting. The system features a long piezoelectric cantilever augmented with two short cantilever-based stoppers. Upon contact with the stoppers, the main beam transitions into a higher-order vibration mode, which inverts the voltage outputs. As the beam switches modes multiple times within a single cycle, frequency up-conversion is realized. The study demonstrates that substantial triple frequency up-conversion can be achieved across a broad frequency spectrum. The system exhibits a peak ratio of triple to fundamental frequency components of 8.86. An RMS power output of up to 3.03 mW was recorded. Additionally, a wireless sensor node was developed and integrated to verify the system's self-powered sensing capabilities.