Flutter-Driven Piezoelectric Wind Energy Harvesting System Based on PVDF Nanofiber for Low Power Applications

With the increase of low-powered electronic devices, there is growing social interest in environmentally friendly energy sources capable of replacing batteries. In this study, a flutter-driven piezoelectric nanogenerator (FD-PENG) using electrospun PVDF nanofiber was fabricated to create a wind-energy harvesting device. The FD-PENG was composed of a PVDF nanofiber mat (active layer) and Al foil (electrodes), with these components encapsulated by polyethylene terephthalate (PET) film using an ordinary coating machine. The short-circuit current generated from the FD-PENG during a bending test was significantly enhanced by optimizing the electrospinning process and with the proper alignment of the PVDF nanofibers. The dynamic behavior of the FD-PENG with respect to various wind speeds was systematically analyzed by categorizing its motion into four distinct modes. The flapping mode, in which the FD-PENG displays the largest amplitude of oscillation, was induced when wind speed was in the range of 3-4m/s. The FD-PENG generated open-circuit voltage of approximately 10 V at a wind speed of 4m/s and exhibited excellent durability over 10,000 cycles. Using a single FD-PENG, maximum power approaching 14.66 μW was achieved under an external load of 1.1 MΩ. Furthermore, the wind speed inducing the flapping mode was modulated by the shape of the FD-PENG. The results here show that the wind energy harvester can be applied at a wide range of wind speeds by modifying the shape of the FD-PENG.