Electrospinning

Electrospinning is a process that allows the fabrication of nanometre-diameter fibers (so-called nanofiber) from polymer solutions. The fibers are formed by evaporating the solvent while thesolution is passing through a high electric field.

The first patent related to this methodology dates back to 1902 by J.F. Cooley and W.J. Morton, who devised a process to disperse fluids through an intense electric field.

Electrospinning allows nanofibres to be obtained from both natural and synthetic polymers. The solution in which the polymer has been dissolved is loaded into a syringe with a needle, called a spinneret, and then extruded through it at a constant flow rate by a pump. An electric field is applied between the spinneret and the collector, that is, the component in which the nanofibres are deposited: both components are therefore electrically charged.

As the solution begins to flow out of the needle, applying a high-voltage electric field induces a droplet deformation in the so-called “Taylor cone” formation. At the tip of the cone, the droplet emits a jetthat rapidly stretches, elongating and thinning itself. The free electrical charges in the starting solution interact with the applied electric field. The potential difference between the solution in the spinneret and the manifold induces the formation of the jets.

The latter are directed from the spinneret to the collector at the same time as the solvent is evaporating. By the time the jets reach the grounded collector, discharging electricity, the solvent has now evaporated and dry, solid fibers are visible.