**2.4. Spinning distance**

Spinning distance was defined as the distance between the spinning tip and the collector. This distance is exactly the route that the electrospun jet experiences. Changing the spinning distance may cause a change in solvent evaporating velocity, the electrical field intensity, and the solidifying state, and thus affect the fiber properties indirectly. When the spinning distance is too short, the fiber will not be thinned enough because of a lack of the whipping process and inadequate solvent evaporation, as a result, the beads may accrue and even prepared fabrics may dissolve back into concentrated solution at this stage [33]. On the contrary, if there is an increase in the spinning distance, and a fixed electric field intensity, smaller fiber can be produced, and naturally, a larger area of deposited non-woven fabrics is prepared [34]. The spinning distance in most cases was set at 7-15 cm.

It should be noticed that near-field electrospinning has been developed for a patterned deposition of nanofiber, in which the spinning distance was set smaller than 1 mm and jet whipping was almost eliminated [35].
