Energy harvesting is one of the most promising research areas to produce sustainable power sources from the ambient environment. Which found applications to attain the extensive lifetime self-powered operations of various devices such as MEMS wireless sensors, medical implants and wearable electronic devices. Piezoelectric nanogenerators can efficiently convert the vastly available mechanical energy into electrical energy to meet the requirements of low-powered electronic devices. Among the piezoelectric materials, poly (vinylidene fluoride) (PVDF) and its copolymers are extensively studied for the development of energy harvesting devices. Due to the outstanding properties such as high flexibility, ease of processing, long-term stability, biocompatibility makes them a promising candidate for piezoelectric generators. Nevertheless, compared to piezoceramic materials, PVDF based generators produce lower piezoresponse. Over the last decades, tremendous research activities have been reported to endorse the performance of PVDF based energy harvesters. This review article mainly focused on the recent progress in the performance improvement with processing methods, piezoelectric materials, different filler loading. The new developments and design structures will lead to an increase in piezoelectricity, alignment of dipoles, dielectric properties and subsequently enhance the output performance of the device. Electronic circuits play a vital role in energy harvesting to efficiently collect the developed charge from the device. Here, we have proposed a detailed description of the electronic circuits. Also, in the application part deals with the recent progress in flexible, biomedical and hybrid generators based on PVDF polymers.

This paper focuses on the numerical simulation of the polypropylene / multi-walled carbon nanotubes (PP/MW CNT) flow into a twin screw mixer, during the mixing phase. The PP/MW CNT behavior obeys an innovating Carreau law enriched temperature built on the rheological properties carried out previously. The polypropylene was mixed with different MW CNTs contents (1, 2, 4 and 8 wt% of MW CNT content) and the rheological tests were performed at shear rate ranges from 10-1 to 2 10 4 s-1 at four temperatures (180, 200, 220 and 240°C). Thus the effects of the temperature and the MW CNTs content on the rheological properties of the PP/MW CNT composites were investigated. The finite element (FEM) analysis of the PP/MW CNT flow allows to compute the velocity, the shear rate and the temperature during the mixing phase period. A good agreement between the experimental measured torque on the screw and the calculated one is shown. Therefore, one can consider that the physical flow is generally well described, awaiting a numerical simulation of the PP/MW CNT mixing phase.