Electrical properties of PVDF films fabricated by direct ink writing

In this study, direct ink writing (DIW) was applied to preparing polyvinylidene fluoride (PVDF) film. The rheological properties of inks were studied, and the influence of process parameters on material properties was systematically investigated by SEM, FTIR, DSC, dielectric, ferroelectric and piezoelectric properties testing. The results show that effective β -phase content of PVDF film prepared by printing parameters with printing needle size of 27G and printing speed of 20 mm/s was 52.38%, which was improved by 51.47% compared with the film prepared by solution casting. The high β -phase content improved the electrical properties of film. This is attributed to the orientation of PVDF molecular chains by the drawing force generated at printing needle and the shear force generated during extrusion. The piezoelectric output voltage increases approximately linearly with increasing finger height from the sensor. The sensitivity of the sensor is 78 mV/N, which is comparable to the performance of one prepared by solution casting and treated with electric polarization. The excellent piezoelectric performance of PVDF film demonstrates application potential in small deformation monitoring.