Design and development of vibrational mechanoelectrical MEMS transducer for micropower generation

The paper is devoted to design, numerical modeling and analysis of vibration-driven mechanoelectrical MEMS transducer based on piezoelectric cantilever-type microstructure, which function is to act as a micropower generator in wireless sensor networks. This study also deals with fabrication and experimental investigation of piezoelectric PVDF thin films intended for energy harvesting applications. The first part of the paper presents finite element model of the transducer, which is a multiphysics one, combining mechanics, piezoelectricity and fluid-structure interaction in the form of squeeze-film damping governed by nonlinear compressible isothermal Reynolds equation. Subsequently the model is subjected to modal, harmonic and transient analyses in order to determine the effect of viscous air damping and geometrical parameters on device dynamical and electrical performance. The second part of the paper considers aspects of formation of PVDF thin films. The quality of the produced thin films and their material characteristics are evaluated by means of scanning electron and atomic force microscopy as well as using X-ray diffractometry and FT-IR spectrometry techniques. Performed experiments reveal that fabricated PVDF samples possess distinct crystalline phases, with alpha-phase being predominant.