Design and analysis of vibration-based piezoelectric energy harvester [EMBARGOED]

Abstract

Despite the common use of batteries, their limitations, such as finite energy capacity and environmental concerns upon disposal, pose significant challenges. Piezoelectric energy harvesters (PEH) provide an infinite operational lifespan for low-power devices and eliminate the necessity for battery replacement. They have emerged as a crucial technology for sustainable energy solutions and a key characteristic for engineering applications, such as sensors and actuators. This study aims to design and analyse PEH devices. A PEH with various cantilever shapes, namely, rectangular, circular, and triangular edges, has been designed with varying substrate materials (rigid, such as structural steel, and flexible, such as polyethylene terephthalate (PET)) in conjunction with piezoelectric materials, namely, lead zirconate titanate (PZT) and polyvinylidene fluoride (PVDF). Finite element modelling was conducted to analyse the output voltages harvested from PEH and its resonance frequencies. Next, three different rectangular edge shapes with materials such as PZT/copper, PVDF/PET, and PVDF without a substrate were prepared, then mounted on a specially designed holder. Vibration was applied to these devices using an electromagnetic shaker, and their resonance frequencies and output voltages were monitored and observed using a digital signal analyser. Moreover, this work proposed a signal conditioning circuit design that includes the design of a charge amplifier and a precision full-wave rectifier. Additionally, the integration of this circuit with the PVDF/PET device was presented in this work. The simulation result indicated that the cantilever with rectangular edges generated the highest output voltage when combined with PZT/steel, reaching up to 1.3914V at a resonant frequency of 250 Hz. In the measurement process, PZT/copper also yielded the highest output voltage of 1.62V at a resonant frequency of 416.167 Hz. The measurement results align with the finite element simulation, where PZT exhibits the highest output voltage compared to PVDF, due to its higher piezoelectric coupling coefficient and higher relative permittivity. Lastly, The PVDF/PET device output was amplified by a charge amplifier from 2.12V peak-to-peak to 4.16V peak-to-peak and then converted to 2.08V peak-to-peak DC voltage by precision full-wave rectifier. This study represents a significant advancement in PEH efficiency enhancement and has the potential to evolve into a sustainable energy solution.