A Lambda-shaped piezoelectric energy harvester for highly efficient vibration energy harvesting

Abstract

Recently, due to the rapid development of portable electronic devices and wireless sensor networks, longer battery life is required to achieve better device performance. Piezoelectric energy harvesters effectively convert mechanical energy into electrical energy. Due to the advantage, several researchers have actively conducted research on piezoelectric energy harvesters. The conventional cantilever piezoelectric energy harvester (CPEH), however, has a disadvantage that strain distribution is not uniform along the length of the beam to which piezoelectric material is attached to produce electrical energy. In order to alleviate the disadvantage of CPEH, we propose a new Lambda-shaped piezoelectric energy harvester (LPEH) which can improve power performance. Both piezoelectric energy harvesters use bimorph cantilever configurations with the parallel connection of piezoelectric layers. Using finite element models, we could find that the LPEH induced higher and more evenly distributed stress than the CPEH under the same test conditions. For the modeling of the harvesters, the Euler-Bernoulli beam theory and Kane's method were used. For the comparison study, design optimizations were conducted for both PEHs. Compared to the CPEH using the same limits for total mass and volume of the piezoelectric materials, we could find that the LPEH was capable of generating more power