Force induced piezoelectric effect of polyvinylidene fluoride and polyvinylidene fluoride-co-trifluoroethylene nanofibrous scaffolds.

Polyvinylidene fluoride and its co-polymer with trifluoroethylene are promising biomaterials for supporting nerve regeneration processes because of their proven biocompatibility and piezoelectric properties that could stimulate cell ingrowth due to electrical activity upon mechanical deformation. This study reports the piezoelectric effect of electrospun polyvinylidene fluoride scaffolds in response to mechanical loading. An impact test machine was used to evaluate the generation of electrical voltage upon application of an impact load. Scaffolds were produced via electrospinning from polyvinylidene fluoride and polyvinylidene fluoride-co-trifluoroethylene with concentrations of 10-20 wt% dissolved in N,N-dimethylformamide (DMF) and acetone (6:4). The structural and thermal properties of scaffolds were analyzed using Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry, respectively. The piezoelectric response of the scaffolds was induced using a custom-made manual impact press machine. Impact forces between 0.4 and 14 N were applied. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry results demonstrated the piezoelectric effect of the electrospun polyvinylidene fluoride and polyvinylidene fluoride-co-trifluoroethylene scaffolds. All the scaffolds exhibited a piezoelectric polar beta-phase formation. Their thermal enthalpies were higher than the value of the initial materials and exhibited a better tendency of crystallization. The electrospun scaffolds exhibited piezoelectric responses in form of voltage by applying impact load. Polyvinylidene fluoride-co-trifluoroethylene scaffolds showed higher values in the range of 6-30 V as compared to pure polyvinylidene fluoride. Here, the mechanically induced electrical impulses measured were between 2.5 and 8 V. Increasing the impact forces did not increase the piezoelectric effect. The results demonstrate the possibility of producing electrospun polyvinylidene fluoride and polyvinylidene fluoride-co-trifluoroethylene scaffolds as nerve guidance with piezoelectric response. Further experiments must be carried out to analyze the piezoelectricity at dynamic conditions.