Electrospinning is a method of using high voltage electric fields to transform polymer solutions into nanofibre. The process involves applying... » More

Electrospinning is a method of using high voltage electric fields to transform polymer solutions into nanofibre. The process involves applying high voltage (~10 kV) to a droplet of solution at the end of a capillary (which is visible on the left in the video). The surface charge on the droplet distorts the shape from that adopted by surface tension into what is known as the Taylor cone. From the tip of this cone a jet is ejected in response to the electric stresses on the fluid at that point. This jet travels towards a grounded collector while thinning rapidly and is eventually collected. This video shows electrospinning in real time followed by high speed video captured at 10000 frames per second and slowed down to a level where we can see what is happening. In real time the jet appears to reach a point where it becomes unstable and starts to bifurcate into many strands, each thin enough to interact with light giving a characteristic rainbow pattern. However when one slows down the action its possible to see a single jet emerge from the droplet and become unstable, settling into a chaotic ring pattern reminiscent of hypocycloid or spirograph. The rings initially form perfectly but likely due to small off axis electric repulsion begin to uncurl and eventually become chaotic. This effect appears to be intrinsic to the process as it is established well before the jet has even reached the opposite electrode. Although literature published by other authors proposes formation mechanisms for the instability the video shown suggests that we might not yet have the full picture as to what drives the production of nanoscale material from this process.

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