Controlled initiation and termination of jetting in near-field electrospinning through voltage-driven surface charge manipulation

Herein, we present a simple and repeatable method of controlling the initiation and termination in near-field electrospinning (NFES) by manipulating local surface charges at the air-to-polymer liquid interface. A series of experiments involving electrical current and voltage measurements, as well as optical/scanning electron microscopy images, suggest that the jetting in NFES can be effectively terminated while keeping microscale cones on the surface of the droplet for reinitiating when a low-level electrical field is maintained. When the applied voltage is increased to the jetting voltage, the sharp-tip geometry of the microcone focuses a sufficient electric field to reinitiate jetting. It has been effectively demonstrated on two-and three-dimensional surfaces that nanofiber patterns can be generated using the presented technology. The capacity to deposit nanofibers on de-mand is a significant advancement for NFES and will promote the use of NFES in a broader range of applications, including printed electronics, nanofiber-based sensors, and biological applications.