Hollow cylindrical near-field electrospining high β-phase crystallisation of large PVDF nanofiber array for flexible energy conversion

This study used near-field electrospining (NFES) on hollow cylindrical process to fabricate permanent piezoelectricity of polyvinylidene fluoride (PVDF)/multi-walled carbon nanotube (MWCNT) piezoelectric nanofibers. Under in-situ electric poling and mechanical stretching during NFES process (X-Y stage 50 mm/sec, rotating velocity 1300 r.p.m, electric field 1×10⁷ V/m, PVDF solution concentration 16 wt%, and 0.03 wt% MWCNT), high β-phase crystallization of large PVDF nanofiber array were demonstrated. From the observation of actuation property, a fixed-fixed single nanofiber was tested under different DC voltage supply. Moreover, flexible nano-harvesters based on the integration of large numbers of nanofibers in series were mounted in a circular rubber band structure to generate high electric potential. Thus, the improvement of NFES process shows interesting potentials in various applications including power scavenge, sensing and actuation.