Table 1.

Parameters affecting nanofiber geometry in the electrospinning process

S. No	Parameter	Remarks
1	Solution Parameters
i	Surface Tension	Due to the possible difference, the charges on the polymer must be high enough to tolerate any surface tension of the solute in the jet to be removed. However, no conclusive correlation with fiber morphology was discovered [23].
ii	Polymer Solubility	The higher the molecular weight, the less soluble it is and the longer it takes to dissolve. The enthalpy of a solute-solvent mixture is equal to the square of the difference in solubility parameters [24]. Polymer solubility affects fiber morphology.
iii	Viscosity	Low viscosity leads to the formation of smooth but beaded fibers. Good solvents have high intrinsic viscosity [25]. Fiber diameter increases with increased viscosity.
iv	Volatility	High volatility leads to solvent evaporating even before the jet reaches the collector, forming porous fibers [23].
v	Conductivity of Solution	Conductivity helps to overcome surface tension. Reagents are added to improve conductivity. Higher conductivity helps to form finer fibers [23].
vi	Molecular weight	The polymer chain size and viscosity are also affected. The greater the molecular weight, the smaller the entanglements [26]. The diameter of the fiber increases as the polymer's molecular weight rises.
vii	Dielectric effect of solvent	The greater the dielectric property, the fewer beads shape and the smaller the diameter of the fabric. The electrospinning jet's bending volatility also rises [27].
2	Process Parameters
i	Voltage	Higher voltages initiate the electrospinning process [28]. At even higher voltages, thick fibers are formed. Lower voltages favor the formation of finer nanofibers [23].
ii	Feed rate	The feed rate is proportional to the fiber diameter and the scale of the beads. A slower feed rate is preferred so that the solvent will evaporate [23].
iii	Effect of collector	The collector plate is electrically grounded to ensure a safe potential difference between the source and the collector. Nonconductors can collect charges on the plane, resulting in fewer fiber deposits [29, 30].
iv	Diameter of Pipette Orifice/ Needle	Clogging and the number of beads in electrospun fibers is reduced by having a limited internal diameter [31].
v	Distance between tip and collector	Lesser distance implies that the jet has to travel lesser to reach the collector plate, not giving it sufficient time to evaporate, forming intra-bonding layers and beads [28, 32]. Larger distances allow more stretching of fibers which decreases the fiber diameter [33].
3	Ambient Parameters
i	Humidity	High humidity affects fiber morphology when water condenses on the fiber surface, increasing the size and depth of the shaped circular pores [23].
ii	Type of atmosphere	Under strong electrostatic fields, different gasses behave differently [23].
iii	Pressure	Lower pressures (below ambient pressure) cause erratic jet formation and solution bubbling at the needle tip. Electrospinning is impractical at extremely low pressures due to the direct discharge of electrical charges [23].
iv	Temperature	Higher temperature helps decrease the diameter of fibers but may not be suitable for proteins and enzymes-based fiber [23].