ABSTRACT
The process of electrospinning has been shown to be effi cient for the fabrication of polymer fi bres ranging in diameter from micrometres down to nanometres. In the electrospinning process, a polymer solution is pumped at a fl ow rate (usually below 1ml/h) through a syringe (spinneret), thereby forming a drop at the tip of the needle. Using a high voltage connected to the syringe, a strong electric fi eld is created between the spinneret and the grounded collectors (target). When the electrical potential is increased beyond a critical value, electric repulsion overcomes the surface tension of the polymer drop, and a jet of polymer is ejected. The movement of charged molecules in the electromagnetic fi eld results in a spiralling trajectory towards the collectors, whereby the solvent evaporates and thin, stretched polymer fi bres are formed on the target. The basic collector, a single metal plate, renders non orientated, mesh like fi bres (Fig 3A). However, the collection of fi bres can be manipulated to achieve orientation (Fig. 3B-H). A routine method for orientated fi bre collection is
to electrospin onto a rotating drum collector (Matthews et al. 2002; Kim et al. 2008; Fig. 3B, H). An alternative approach is to generate suspended mats of orientated fi bres between two parallel collectors, known as the gap method of alignment (Dalton et al. 2005; Gerarado-Nava et al. 2009; Fig. 3 D, E, F and G). Others have constructed hollow conduits from microand nanofi bres by electrospinning onto a rotating copper wire which was removed at the end of the spinning process (Panseri et al. 2008).
