Direct fabrication of polymer nanofiber membrane for piezoelectric vibration sensor

A modified electrospinning method was introduced to fabricate high-performance piezoelectric membranes directly, where a copper sheet was fixed at the end of the needle and a rotating collector was used. This electrospinnig process provides a uniform parallel electric field with a combined action of strong electric field strength and high stretch ratio to orient poly (vinylidene fluoride) (PVDF) molecular chain, and promote polymorphic change from α-phase to β-phase, which enhances its piezoelectric performance. PVDF samples in different forms were prepared and evaluated by testing their respective piezoelectric performance. The results show that maximal piezoelectric response of the untreated PVDF nanofiber membrane (259 mV) is much better than that of electric poling spin coating film (123 mV) at an excitation voltage of 1.2 V and frequency of 15 Hz. The piezoelectric performance of the untreated membrane shows linearity with excitation voltage and can be further enhanced by electric poling.