In this study, with near-field electrospinning technique of PVDF (Polyvinylidene fluoride) piezoelectric nano-fibers and the additional multiwalled-carbon nanotubes(MWCNT), both mechanical strength and piezoelectric characteristics of a single nano-fiber were discussed. Then the behavior of piezoelectric fiber actuators was realized using inverse piezoelectric effect. Near-field electrostatic technology can be used to fabricate PVDF piezoelectric fibers with an excellent piezoelectric property compared with film structures due to a higher piezoelectric coefficient and energy conversion efficiency. It is more suitable to produce micro transducers. By adjusting velocity of a fully parametric x-y stage, DC voltage, and the distance between the needle and collection plate, the morphology and polarization intensity of piezoelectric fiber can fully be controlled. In addition, the optimal parameters of PVDF solution such as PVDF powder weight percentage and MWCNT were also discussed. From the observation of XRD (X-ray diffraction), it reveals a high diffraction peak at 2£c=20.8¢X of piezoelectric crystal £]-phase structure. Finally, the actuation property was tested using DC voltage supply, and fiber has significant deflection in the experiment. The vertical deflection can be observed and compared with model solution of piezoelectric cantilever structure. In the fiber¡¦s direct piezoelectric effect, the result shows that fiber can produce an open circuit voltage of 15mV under a low frequency vibration of 7Hz.

This study presents near-field electrospinning (NFES) on flat and hollow cylindrical process to fabricate permanent piezoelectricity of polyvinylidene fluoride (PVDF)/ multi-walled carbon nanotube (MWCNT) piezoelectric nanofibers. Then the mechanical properties of fibers were measured. PVDF is a potential piezoelectric polymer material combining desirable mechanical, thermal, electrical properties with excellent chemical resistance. The existing researches mostly focused on piezoelectric thin film process. However, the research of characteristic about piezoelectric fiber is little. The methods of measurement of the mechanical properties (Young¡¦s modulus, hardness, and tensile strength¡Belongation) of the electrospun PVDF/MWCN composite nanofiber were carried out by using nano-indention test (MTS Nanoindenter Windows XP System) and tensile test (Microforce Testing System). By setting electric field (1¡Ñ107 V/m), rotating velocity (900 rpm) of the hollow cylindrical glass tube on a motion X-Y stage (2 mm/sec) and PVDF solution concentration (16 wt%), and MWCNT (0.03 wt%), in-situ electric poling, mechanical stretching and morphology of PVDF nanofiber were demonstrated. After the experiments of nano-indention test and tensile strength test, it is suggested that the good mechanical properties in NFES on cylindrical process. The results show that the mechanical properties of composite nanofiber are better than the conventional NFES process. The Young¡¦s modulus of 16% PVDF fiber prepared by cylindrical process is 0.89 GPa and hardness is 26.5 MPa. The mechanical properties were increased 56.2% and 49.4% after adding 0.03% of MWCNT, corresponding to 1.39 GPa and 39.6 MPa. The tensile strength was increased 32.7% and elongation at breaking point was increased 35% after adding 0.03% MWCNT.