Computational and Experimental Comparison of the Effect of Porosity on the Piezoelectric Characteristics of Polyvinylidene Fluoride (PVDF) Thin Films

Abstract

Polyvinylidene Fluoride (PVDF) is a piezoelectric polymer that is uniquely suited for biosensing applications due to its biocompatibility, sensitivity to changes in pressure, and simplicity to fabricate. PVDF thin films have shown potential in the application of hemodynamic flow sensing and monitoring the effects on blood flow caused by prosthetic valve implantation via the transcatheter aortic valve replacement (TAVR) operation. The piezoelectric performance of PVDF films can be influenced by the porosity of the material. In this study, strain tracking was performed on thin film PVDF specimens with various levels of porosity and pore sizes to determine the mechanical properties of the specimens. The mechanical properties were used to model the PVDF material in COMSOL Multiphysics software, in which compression and tensile test simulations were performed to determine the piezoelectric coefficients of the PVDF. Experimental compression tests were performed so that the results could be compared with the simulated results. The simulated results were also compared with experimental results achieved from a previous study through tensile testing of PVDF. Simulated results showed that piezoelectric performance of PVDF increased as porosity increased, and specimens with the smallest pore sizes exhibited the highest performance. Piezoelectric coefficients d33 and d31 ranged from 4.8-16.9 pC/N and 16.4-47.2 pC/N, respectively, which resemble the expected values based on literature. Experimental tensile test results closely resembled the simulated results. However, experimental compression tests showed insignificant change in the piezoelectric performance of PVDF as the porosity of the material increased.