Study On The Low-frequency Energy Harvester Based On PVDF Piezoelectric Fibers

Nowadays,the advancement of microelectronic devices have been fully promoted and the applications have been expanded into various fields.With the development of technology,the microelectronic devices for business should be produced without pollution and the endurance and reliability need to be further strengthened.With regards to the wearable microelectronics,it is necessary for them to be more flexible while avoiding physical harm.It is effective for microelectronic devices to improve the performance and meet the functional requirements above by optimizing the power supply mode.For the purpose of providing reproducible energy for electronic devices sustainably,the researchers devote themselves to study how to harvest energy from the environment.According to previous studies,the piezoelectric energy-enabling devices are suitable for extracting energy generated by human motion.Due to the advantages of easy processing,simple structure,strong flexibility and humanity-friendly,it is particularly suitable to prepare energy harvesters and power wearable devices based on PVDF.In this paper,a low-frequency piezoelectric energy harvester based on PVDF piezoelectric fibers is presented.The key points to improve the piezoelectric performance of PVDF are summed up in this paper.The electrostatic spinning method is chosen to prepare the PVDF nanofibers and TiO₂ nanoparticles are added in the nanofibers for the increase of ? phase.After that,the performance improvement of PVDF piezoelectric performance is verified by means of scanning electron microscopy?SEM??transmission electron microscopy?TEM?,infrared spectrum and X-ray diffraction.According to the materials science,structural mechanics and other knowledge,the mathematical model of the corrugated cantilever beam is established for the research of the structure.The relationship between the natural frequency of the corrugated cantilever beam and the thickness of the cantilever beam,the amplitude of the corrugation and the number of corrugations in cantilever beam is analyzed based on the mathematical model.For the further verification of the theoretical analysis,the finite element model of corrugated cantilever beam was established with ANSYS and the effects of structure parameters of cantilever beam on the output characteristics of the piezoelectric energy harvester was obtained.Then,the frequency response of the low-frequency energy harvester based on the corrugated curved cantilever beam is discussed through simulated analysis.Existing power management circuits are summarizes in this paper.Due to the low trigger voltage of ADP5091 chip,the chip is adopted to improve the traditional rectifier filter circuit on account of on the properties of energy harvester and the characteristics of applications.Except for the improvement of energy conversion efficiency,the energy storage component is integrated and the functions of the circuit is expanded.In this study,the piezoelectric energy harvester was made based on the PVDF/TiO₂ nanofibers and the ultra-low frequency vibration test and calibration system was used as the test platform to conduct experiments on the characteristics of the energy harvester.The best matching resistance and the maximum output power of the low-frequency energy harvester are obtained according to the experiments of the device working with different loads.In this study,a shoe is fabricated integrated with the low-frequency energy harvester and the energy management circuit.The shoe can be used as the power supply device of the low-power pedometer,which verifies the effectiveness of the energy management circuit and the low-frequency working ability of the PVDF piezoelectric energy harvester based on PVDF/TiO₂ nanofibers.