A Polymer-based Piezoelectric Vibration Energy Harvester with a 3D Meshed-Core Structure

Abstract

In this study, we fabricated a flexible 3D mesh structure with periodic voids by using a 3D lithography method and applying it to a vibration energy harvester to lower resonance frequency and increase output power. The fabrication process is mainly divided into two parts: three-dimensional photolithography for processing a 3D mesh structure, and a bonding process of piezoelectric films and the mesh structure. With the fabricated flexible mesh structure, we achieved the reduction of resonance frequency and improvement of output power, simultaneously. From the results of the vibration tests, the meshed-core-type vibration energy harvester (VEH) exhibited 42.6% higher output voltage than the solid-core-type VEH. In addition, the meshed-core-type VEH yielded 18.7 Hz of resonance frequency, 15.8% lower than the solid-core-type VEH, and 24.6 μW of output power, 68.5% higher than the solid-core-type VEH. The advantage of the proposed method is that a complex and flexible structure with voids in three dimensions can be relatively easily fabricated in a short time by the inclined exposure method. As it is possible to lower the resonance frequency of the VEH by the mesh structure, use in low-frequency applications, such as wearable devices and house appliances, can be expected in the future.

Recent advances and future prospects in energy harvesting technologies

“…[34][35][36] Moreover, piezoelectric vibrational energy harvesters with a flexible 3D structure fabricated by a microfabrication process are expected to cover low frequencies and achieve a large strain, and are attracting attention for use in wearable devices. 37,38) Ionic liquids, 39) fluorine-containing polymers, 40,41) parylene C 42) and hydroxyapatite 43) have been intensively developed as materials for use in electrostatic electret-type energy harvesters.…”

Fabrication of Solidified Ionic Liquid with 3D Microstructures and Its Application to Vibration Energy Harvester

“…The sample with nanosized unevenness was prepared by oxygen ashing (16) and the samples with a microsized 3D structure were formed by 3D lithography. (13)(14)(15) In the 3D lithography method, both a photoresist-coated substrate and a photomask are fixed to an adjustable table that controls the table angle and rotation speed. The substrate is exposed from an inclination direction while rotating at a constant speed.…”

“…We propose a novel forming method to simultaneously perform the solidification, polarization, and microstructure transfer of the solidified ionic liquid using a mold with 3D micropatterns fabricated by 3D lithography. (13)(14)(15) The power generation performance characteristics of the fabricated VEHs were evaluated by vibration tests.…”