Energy Harvesting Enhancement by Vibration Mode Coupling of Piezoelectric Cantilever Beam

The rapidly growing demand for wireless sensing technology has necessitated the advancement of compact energy recovery systems. Piezoelectric cantilever beams have gained significant attention as an effective energy recovery solution. However, the energy harvesting capability of a piezoelectric cantilever is typically constrained by the narrow bandwidth of resonance frequencies, particularly during low-frequency vibrations. This paper proposes an innovative solution to power emerging wireless sensing systems, leveraging both bending and twisting modes to attain broadband characteristics. The process begins with developing a finite element model to assess the proposed structure’s performance. By splitting the piezoelectric plate into two sections, charge neutralization in twisting modes is eliminated, while the adjustment of the inertia moment allows the natural frequency of the twisting mode to match the desired frequency bands. A prototype of this design was subsequently fabricated for experimental validation. The findings confirm the effectiveness of the divided piezoelectric plate in boosting the output energy in the twisting mode. Additionally, by stimulating different mass positions, the first three natural frequencies can be adjusted to fall within the 0–50 Hz range, with the twisting mode spanning a range of 14–21 Hz. The study proves the feasibility of coupling bending and twisting modes for broad power generation with a piezoelectric cantilever, paving the way for self-powered wireless sensing systems.