Co-axially electrospun PVDF fibers with hollow wall to enhance potential output

In this study, a CNFES (cylindrical near-field electrospinning) process and a metallic coaxial needle injector were used to fabricate piezoelectric PVDF (polyvinylidene fluoride) hollow-walled fibers. Piezoelectric fibers devices with interdigitated electrode were fabricated to capture potential signal. First, the PVDF powder was mixed in the acetone solution and the fluorosurfactant was dissolved with the dimethyl sulfoxide to prepare PVDF macromolecular solution. Second, PVDF macromolecular solution was filled in the outer needle, air was filled in the syringe of inner needle and the metal needle coaxial injector contacted a high power supply. When the PVDF droplet in the coaxial needle was subjected to high electric field, the droplet overcame surface tension of the solution and became a Taylor cone, extremely fine hollow-walled PVDF fibers was spun out on collectors. The hollow-walled PVDF fibers were collected by a cylindrical device on the XY-axis digital platform. The diameter of hollow-walled PVDF fibers could be controlled by adjusting the electric field and the rotating speed of the cylindrical collector. The experimental images reveal structures of the hollow-walled PVDF fibers. In comparison of the solid PVDF and the hollow-walled PVDF fibers, the solid PVDF fibers with IDT (interdigitated electrode) could generate maximum peak voltage of 35.731-213.827 mV at frequencies of 2-9 Hz, whereas the hollow-walled PVDF fibers with IDT electrode could generate maximum peak voltage of 44.092-246.088 mV. The hollow-walled fibers with higher area/volume ratio and mechanical stiffness can produce more potential voltage.