Influence of electrospinning parameters and post-treatment on the structural alignment and electrical properties for...

Electrospun polyvinylidene fluoride (PVDF) membranes possess exceptional piezoelectricity and mechanical flexibility, holding significant potential for diverse applications such as wearable electronics and biomedical scaffolds that mimic the extracellular matrix. However, integrating these electrospun membranes into practical piezoelectric devices necessitates electrical interconnections with conductors, a process that frequently demands post-treatments such as compression or thermal compression depending on the device specifications. These post-treatments induce not only superficial mechanical deformations on the fibers but also profound alterations in internal properties, including the crystalline phase and electrical resistance of the PVDF. In this study, we optimized the effects of various electrospinning parameters on PVDF fiber formation and systematically investigated the multidimensional changes in morphology, electrical impedance, and piezoelectric behaviors under compression and thermal compression. The experimental results revealed that post-treatment altered the fiber networks in a sophisticated manner; while it effectively enhanced electrical conductivity by eliminating internal pores and stabilizing the polar β-phase crystallinity during thermal compression, it concurrently constrained the device's relative resonance energy conservation and frequency sensitivity due to localized overdensification. As these post-treatment processes induce an intrinsic trade-off between structural configuration and electrical conversion efficiency, rather than a simplistic improvement or degradation, the necessity and specific conditions of post-treatment must be strategically determined based on the targeted application. Consequently, the comprehensive metrics and mechanisms elucidated in this study are expected to serve as a pivotal physical and electrical framework for optimizing and tailored-designing electrospun PVDF membranes for advanced piezoelectric devices and biomedical systems.