Enhancing Bandwidth of Cantilever-Based Energy Harvester Using a Passive Multi-Chamber Movable Mass Repositioning...

Piezoelectric energy harvesters (PEHs) have emerged as a promising solution for self-powered small-scale electronic systems; however, their narrow operational bandwidth limits performance under varying excitation conditions commonly found in ambient environments. To address this limitation, this study proposes a passive multi-chamber proof-mass design containing internal free-moving masses to enhance the frequency bandwidth of a PEH through nonlinear dynamics. Multiple proof-mass models were designed and experimentally evaluated using tungsten and Teflon spherical movable masses under 0.5 g and 1 g excitation levels. Design alterations include varying the number of chambers, which in essence reduces the maximum lateral displacement of the movable mass. Baseline characterization was first conducted using empty proof-mass configurations, followed by fixed-mass and free-mass testing to isolate the effects of dynamic mass repositioning. The results demonstrate that baseline and fixed-mass configurations remained limited to bandwidths in the 5-8 Hz range. In contrast, free-mass configurations produced significant bandwidth enhancement across all models. The largest bandwidth increase consisted of a multiple-chamber proof-mass design, which resulted in a bandwidth of 72 Hz using tungsten rolling spheres at 1 g excitation, corresponding to a 1400% increase relative to the baseline conditions.