Advanced electrospinning using circle electrodes for freestanding PVDF nanofiber film fabrication

Here, we investigate a circle electrode in the electrospinning process for the fabrication of substrate-free, freestanding nanofiber films. Circle electrode-based electrospinning is controlled by varying the applied voltage and the metal needle tip-to-collector distance. The equipment used for the voltage source and syringe pump is the same as those in traditional electrospinning. A hollow cylinder is used as the circle electrode to ensure stable electrostatic conditions on the top surface of the cylinder collector. Many studies of electrospinning have presented parameters for optimal film fabrication that are inadequate for film fabrication on wire electrode-based electrospinning. To overcome obstacles inherent to substrate-free film fabrication, the voltage and tip-to-collector distance are controlled in the circle electrode-based electrospinning process. Numerical simulation is used to determine the electric field in the electrospinning process for quantitative analysis. Under voltages of 6–18 kV and tip-to-collector distances of 30–100 mm, a freestanding film is successfully fabricated on a circle electrode with 20-mm inner diameter. The freestanding electrospun film can be transferred as a coating to a non-planar surface without using additional processes. Thus, the electrospinning process using the circle electrode collector was successfully optimized for freestanding film fabrication. Substrate-free electrospun films can be applied to multifunctional filters for dust filtration with humidity blocking. Regarding future applications, the circle electrode-based electrospinning process verified the potential for integrating freestanding electrospun films into organs-on-chip, biochemical sensors, and microfluidic analysis systems.