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Jiajun Lin1 Henry Sodano1

1, University of Michigan-Ann Arbor, Ann Arbor, Michigan, United States

As piezoelectric polymers, Poly (vinylidene fluoride) (PVDF) and its copolymers are attractive in energy conversion applications because of their highly efficient electromechanical interaction as well as their flexibility and biocompatibility. Such unique properties have been widely utilized in various applications such as sensors, actuators and energy harvesters. However, in order to achieve high piezoelectric phase in PVDF, traditional manufacturing methods (i.e. mechanical drawing and electrical poling) restricted the form of PVDF based devices within two-dimensional films. Additive manufacturing techniques of PVDF have been investigated in the past years to achieve three dimensional structured devices, yet challenges still exist in obtaining piezoelectric active phase in 3D printed PVDF and applying electrical poling on complicated structures. Here, we introduce a novel additive manufacturing method to fabricate high piezoelectric 3D structures of PVDF. The developed method utilized a setup combining electrospinning and 3D printing, where PVDF are first electrospun into nanofibers and then accurately deposited on a grounded substrate using an automated stage. During the electrospinning process, mechanical stretching and electrical poling take place simultaneously on the spun PVDF nanofibers through the electric field applied between the printing head and substrate. This allows the printed PVDF forms in high quality β-phase which is most preferred in piezoelectric application because of their plannar chain conformation, meanwhile aligns the dipoles in one direction. In this wat, sufficiently poled PVDF-based piezoelectric devices can be fabricated in only one step. This novel electrospun 3D printing method is expected to break the restrictions in PVDF fabrication and extract more potentials of PVDF as soft piezoelectric materials in advanced applications such as smart skins and artificial muscles.

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