Abstract
Piezoelectric energy harvesting using cantilever-type structures has been extensively investigated due to its potential application in providing power supplies for wireless sensor networks, but the low output power has been a bottleneck for its further commercialization. To improve the power conversion capability, a piezoelectric beam with different electrode coverage ratios is studied theoretically and experimentally in this paper. A distributed-parameter theoretical model is established for a bimorph piezoelectric beam with the consideration of the electrode coverage area. The impact of the electrode coverage on the capacitance, the output power and the optimal load resistance are analyzed, showing that the piezoelectric beam has the best performance with an electrode coverage of 66.1%. An experimental study was then carried out to validate the theoretical results using a piezoelectric beam fabricated with segmented electrodes. The experimental results fit well with the theoretical model. A 12% improvement on the Root-Mean-Square (RMS) output power was achieved with the optimized electrode converge ratio (66.1%). This work provides a simple approach to utilizing piezoelectric beams in a more efficient way.
Highlights
Energy harvesting, as an alternative energy source for low-power electronics, has prompted great research interest in the last decade
We present a theoretical model to analyze the influence of electrode coverage on the electromechanical behaviour of the piezoelectric harvester under tip excitation
The electrode coverage ratio is investigated in order to improve the output power of piezoelectric energy harvesters under tip excitation
Summary
As an alternative energy source for low-power electronics, has prompted great research interest in the last decade. Energy harvesters using cantilever structures typically operate at their first vibration mode In this mode, the strain distribution varies linearly along the length direction from the maximum at the root to zero at the free end, but the electric potential is even when electrodes are fully covered on the piezoelectric layers. The tip excitation method ( known as “Frequency Up-Conversion”) demonstrates broadband capability by beam plucking using magnetic force [27,28] or direct impacts [29,30] This method has been extensively adopted and studied in recent years for different energy harvesting scenarios, including harvesting from human motion [31], airflow [32], and rotational sources [33], and this method has been regarded as a better way for piezoelectric energy harvesting in many practices.
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