Development and Optimization of an Alternative Electrospinning Process for High Throughput

Abstract

In this work, we investigate the prospect of electrospinning from the simplest aperture-free system, a flat plate on which polymer solution is placed as droplets or undergoes a gravity-assisted flow. We fabricated nanofibers with a similar fiber diameter and diameter distribution at similar voltages and working distance as that in an aperture-based system, however with much more flexibility to scale up the process, and with no openings or nozzles that can clog. We verify that the field gradient at the site of jet formation is important. In particular we show that the relatively homogeneous electric field on the plate surface does not promote electrospinning as compared with the significantly more inhomogeneous field at the needle tip in the needle-plate configuration. However, the strong field gradient at the plate edge, allows electrospinning from unconfined droplets of the polymer solution and formation of fibers with very similar diameters and diameter distributions as those fabricated by traditional needle electrospinning for the same polymer solution. Further we show that this edge-plate methodology can be extended to systems with many “edges†and curved edges (such as those from a hollow cylinder) for massively-parallel electrospinning (that is, higher throughput). We report a detailed examination of the changes in fiber diameter, diameter distribution, and mat porosity as a function of the electric field magnitude and geometry, and conclude that the process is quite stable over a range of experimental conditions. The connection between fiber properties and spinning conditions via changes in the length and duration of the linear region and the degree of whipping is discussed in the context of comparing edge-plate and needle-plate electrospinning. Not only do these results address issues specific to such a surface-based, parallel aperture-less electrospinning approach, they also continue to expand understanding of electrospinning in more general terms.