A sandwiched piezoelectric transducer with flex end-caps for energy harvesting in large force environments
Journal of Physics D: Applied Physics
Open access under a CC BY 3.0 licence: https://creativecommons.org/licences/by/3.0
This paper presents a sandwiched piezoelectric transducer (SPT) for energy harvesting in large force environments with increased load capacity and electric power output. The SPT uses (1) flex end-caps to amplify the applied load force so as to increase its power output and (2) a sandwiched piezoelectric-substrate structure to reduce the stress concentration in the piezoelectric material so as to increase the load capacity. A coupled piezoelectric-circuit finite element model (CPC-FEM) was developed, which is able to directly predict the electric power output of the SPT connected to a load resistor. The CPC-FEM was used to study the effects of various parameters of the SPT on the performance to obtain an optimal design. These parameters included the substrate thickness, the end-cap material and thickness, the electrode length, the joint length, the end-cap internal angle and the PZT thickness. A prototype with optimised parameters was tested on a loading machine, and the experimental results were compared with simulation. A good agreement was observed between simulation and experiment. When subjected to a 1-kN 2-Hz sinusoidal force applied by the loading machine, the SPT produced an average power of 4.68 mW. The application of the SPT as a footwear energy harvester was demonstrated by fitting the SPT into a boot and performing the tests on a treadmill, and the SPT generated an average power of 2.5 mW at a walking speed of 4.8 km per hour.
The authors gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) in the UK through funding of the research into ‘En-ComE-Energy Harvesting Powered Wireless Monitoring Systems Based on Integrated Smart Composite Structures and Energy-aware Architecture’ (EP/K020331/1).
This is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.
Published online 22 June 2017