Enhancement ultra-low-frequency wave energy harvesting through a piezoelectric energy harvester based on C-shaped cantilever beams

To realize efficient energy harvesting in ultra-low-frequency (<1 Hz) wave environment, this paper proposes a piezoelectric energy harvester based on C-shaped cantilever beams (C-PEH). Under wave excitation, the C-shaped cantilever beam can be deformed substantially to enhance its power output. The compact combination of gravity pendulum and magnetic plucking mechanism enables the C-PEH to adapt to the multi-directional and wide frequency band of wave excitation. Theoretical and simulation analyses are conducted to estimate the magnetic and vibration coupling characteristics of C-PEH. A prototype and test systems are constructed to evaluate the output performance of C-PEH. The test results indicate that the C-PEH can reach a peak power of 58.89 mW and an RMS power of 9.81 mW at a frequency of 0.8 Hz. Under the water wave environment, the C-PEH can easily light up 203 LEDs at the same time or power up a thermo-hygrometer with wireless transmission ability. The C-PEH also appears to have a good adaptability for corrosion and biofouling in marine environment. This research can potentially contribute to a novel technique for collecting ultra-low-frequency wave energy and powering offshore sensor nodes.