A Cavity Structure based Flexible Piezoelectric for Low-Frequency Vibration Energy Harvesting

Abstract

Piezoelectric energy harvesters (PEH) can be used in many areas of application, including human walking, railways, pavements and bridges. Piezoelectric energy harvesters are currently based on two types of external forces, namely pressure load and mechanical oscillation or vibration. A vibration energy harvesting (VEH) is a mechanical oscillation in a piezoelectric energy harvester that harvested electric energy. In the market, there is available energy harvesting device in good electric energy harvesting and very sensitivity. However, the price is too high and the fabrication process is too complex. Furthermore, one of the aimed of the research is to install the energy harvesting device at rotary compressor machine which has noise vibration frequency at 1 kHz to 10 kHz. This paper presented a cavity structure-based flexible piezoelectric vibration energy harvester (FPVEH) based on an IDE circuit for low-frequency vibration applications. A cavity structure (IDE circuity) combine with the flexible circuit (polyimide) and flexible membrane (polyvinylidene fluoride, PVDF) will increase the electric energy harvesting and sensitivity of the device. Therefore, the four designs (Design A to D) are used to investigate the effect of the electrode finger width and the gap between the electrode fingers (to investigate the cavity structure applying in the design). All designs have been characterized by FEA simulation using COMSOL Multiphysics 5.0 and experimental work using a sieve shaker vibration machine. A sieve shaker machine is worked as vibration frequency calibrator. However, the sieve machine can operate at 5 kHz and 7 kHz. Since these two vibration frequencies are in targeted vibration frequency. It is used as vibration frequency calibrator in this experimental work. The results from the FEA simulation and experimental work show the Design D has the highest electric energy harvesting compare to other designs. It has electric energy harvesting at 27.3 V for 1 minutes period. Design D has a wide electrode finger width and the wide gap between electrodes compare to other designs. The vibration frequency was also given the impact to energy harvesting whereby the vibration frequency at 5 kHz has the highest electric energy harvesting compare to vibration frequency at 7 kHz.