Broad bandwidth piezoelectric energy harvester by a flexible buckled bridge

A piezoelectric vibration energy harvester with a broad bandwidth (>15 Hz) is proposed based on a flexible self-buckled bridge. The polymer sheet, thin metal foil, and thinned piezoelectric ceramic film are bonded to constitute the flexible buckled bridge with the total thickness of 200 μm. Its good flexibility is benefit to obtain low resonant frequency (<200 Hz). A "T" shaped proof mass is used to provide a concentrated force at the center of the bridge for buckling easily and decrease the resonant frequency. The natural buckled arc after the bonding process results in a nonlinear phenomenon at the excited acceleration of 0.25 g. The harvester is capable of achieving a maximum peak open-circuit voltage of 15.18 V and maintaining a bandwidth of 15 Hz (90-105 Hz) at an applied acceleration amplitude of 2.0 g. Meanwhile, the harvester generates the maximum effective power of 0.6 mW and the maximum effective power density of 6.9 mW/cm³ at 2.0 g and 105.3 Hz. The normalized power density reaches 0.36 mW cm^-3 g^-2 Hz^-1. The harvester with larger proof mass results in low resonant frequency and a broader bandwidth of 30 Hz (67-97 Hz). Moreover, the harvester performs good reliability at an acceleration amplitude of 2.0 g.