Feipeng Wang, et al. 2015 IEEE CEIDP, Ann Arbor, MI, USA, 2015, 80-83.
By uniaxially stretching polyvinylidene fluoride (PVDF) film at 110 °C at different rates, piezoelectric and thermoelectric properties can be imparted to PVDF. This is mainly achieved through the crystal phase transition from non-polar α to polar β. In addition, the uniaxially stretched PVDF film also shows the potential to produce electricity from renewable energy sources such as water.
Mechanical stretching and energy harvesting of PVDF Film
· PVDF films with an average thickness of 50 μm (40 mm × 40 mm) that were not pre-stretched were used in the study. Using a material-testing apparatus with circulating hot air to maintain a temperature of 110°C, the films were uniaxially stretched. The stretching process involved increasing the length of each film to 4.5 times its initial length at stretching-ratio rates ranging from 0.025 to 25/min.
· For the purpose of harvesting energy from falling water drops, poled PVDF film strips with a metallized area of approximately 16 mm × 4 mm (with vacuum deposited Al as electrode and a thickness of around 0.02 mm) were affixed to a polyester plate to form a structurally stable setup. This piezoelectric structure was securely attached on one end to a stiff support, with the other end left free to receive impacts from water drops weighing 8 or 50 mg, released from different heights. Impact pressure was adjusted by releasing water drops from various heights above the samples to observe the impact on voltage generation.
