Vibration energy harvesting and internal electric potential of (Na,K)NbO₃/polyimide piezoelectric composites

A composite structure of piezoelectric particles and soft polymer materials is a promising component vibration energy harvesters. However, the harvesting behavior which originates from ceramic inside has not been clarified. In this study, (Na,K)NbO3/polyimide composites sheets with NKN fraction 0–40 vol% were fabricated open-circuit voltage was measured. The increased nonlinearly 0.72 to 2.21 V increasing particle (10%–30%) experimental results confirmed using microstructure based finite element method electric potential electromechanical coupling coefficients higher value in content 30% particles. Analysis indicates that internal matrix under strain could be an important factor for macroscopic constant electrical output.