Bi-Directional Piezoelectric Multi-Modal Energy Harvester Based on Saw-Tooth Cantilever Array

Area of Science:

• Mechanical Engineering
• Materials Science
• Electrical Engineering

Background:

• Traditional energy harvesters often suffer from limited operational bandwidth and stability issues under varying excitation conditions.
• Piezoelectric materials offer a promising route for vibration energy harvesting due to their electromechanical coupling properties.

Purpose of the Study:

• To investigate the performance of a bi-directional, multi-modal piezoelectric energy harvester based on a saw-tooth cantilever array.
• To analyze the impact of seismic masses and rigid connections on resonant frequencies and operational stability.
• To evaluate the harvester's response to varying excitation frequencies and angles in the XY plane.

Main Methods:

• Numerical simulations and experimental investigations were conducted on a four-cantilever piezoelectric array.
• Seismic masses were strategically placed to reduce resonant frequencies and enhance stability.
• The multi-modal operation principle was leveraged to broaden the effective frequency range.
• Electrical characteristics, including output power, were measured under dynamic excitation.

Main Results:

• The proposed energy harvester exhibits four resonant frequencies within the 10 Hz to 160 Hz range.
• A Z-shaped seismic mass at the array's center improved output stability across a wide angular range.
• The harvester demonstrated multi-modal operation, effectively utilizing bending deformations across changing excitation frequencies.
• An average output power of 15.3 mW was achieved at an excitation amplitude of 0.5 m/s² and excitation angles from 0° to 350°.

Conclusions:

• The developed piezoelectric energy harvester effectively achieves bi-directional, multi-modal energy harvesting.
• The design ensures stable electrical characteristics and broad operational bandwidth, even with changing excitation angles.
• This innovative design holds significant potential for powering low-power electronic devices in diverse environments.