Development of low-profile piezoelectric energy harvester for high load application

This paper examines the feasibility of a low-profile piezoelectric energy harvester that is particularly useful in application where it is used as power source from high mechanical load and imbedding it in the limited space. Two low-profile energy harvesting devices - a piezoelectric ring transducer and set of PZT stacks are designed and tested. The first proposed energy harvester is composed of a ring transducer, metal outer ring, and cymbal metal end caps. The top and bottom cymbal metal end caps are placed inside the ring and transfer the applied mechanical load on the apex to the inner circumference of the piezoelectric ring transducer by compressing it. The new design is beneficial because applied load gives rise to compressive stress in the piezoelectric layer. A second design is introduced using an array of piezoelectric stacks arranged around cymbal shaped springs. By using compressive stress to the PZT, energy generating performance of the proposed design can be significantly improved comparing to the previous cymbal design using either PZT mono-layer or unimorph PZT. In addition, for the new design high shear strength of the bonding layer is not required to resist amplified radial stress through metal end caps comparing to the previous design.