Factors that affect the electrospinning process

The distance between the tip and the collector is a factor easily neglected. The distance is related to the solvent evaporation and the electrostatic force. Thus, with the increasing distance, the solvent can evaporate completely and the fiber diameter becomes smaller. 

However, if the distance is too great, this causes failure of the fiber formation. If the distance is too short, the solvent may not be completely evaporated, resulting in a larger fiber diameter. Reducing the distance also can increase fiber fusion and adherence to the collector surface [15]. 

The tip diameter is closely related to the formation of a stable Taylor cone, but it does not have an obvious relationship to the fiber diameter. In general, the tip inner diameter is smaller than 2 mm. The typical size of the syringe needle is 16G to 23G. 

Besides the above-noted parameters, there exist some other factors affecting electrospinning, such as the surrounding environment (e.g., humidity [20]). However, all these parameters interact and cannot be individually considered to achieve a perfect fibrous scaffold. All parameters must be comprehensively studied and optimized for electrospinning control. 

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In theory, any factor that affects the electrospinning process also provides a means to control the fibre morphology. In practice, however, only factors with a noticeable and reliable influence on fibre morphology can be employed for this purpose. Methods of controlling the fibre morphology have been reported based on either the operating parameters or the material properties. 

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