Fiber Material and Electrode Configuration Selection in Designing Piezoelectric Macro Fiber Composites

The use of Macro Fiber Composite (MFC) piezoelectric harvesters has gained a great attention in the last decade. These piezoelectric composites are made of polymers reinforced with PZT piezoceramic fibers. Piezoelectric ceramics have outstanding properties but suffer from high stiffness. In contrary, polymers offer high flexibility. The MFC structures combine the benefits of the fibers and polymers needed for specific applications. Few studies have attempted to provide clear indication on the best design of MFC structures for energy harvesting. An attempt to answer this question is addressed by this paper through a simple criterion that may be considered in routine piezoelectric material evaluation. The top and bottom surfaces of the MFC are covered by interdigitated-electrodes IDEs that deliver the electric field along the fibers. The lack of researches on the effect of the electrode design on the generated output power has stimulated the research presented in this paper. In this paper, the MFC geometry is maintained the same while varying the fiber materials and the electrode spacing. This can be exploited to enhance the contact between the piezoelectric fibers and the electrodes and to guarantee a more uniform electric field in the fibers. The PMN-42%PT piezoelectric fiber material was found to provide the best electrical outcomes owing to its higher figure of merit (FOM) \(\left( {d_{33,p} .g_{33,p} } \right)\) . Furthermore, the maximum power output is attained for the electrode spacing \(L_{eq} = 800 \, {\rm{\mu }}{\text{m}}\) .