Electrospinning is a nanofiber fabrication technique that uses electrostatic forces to produce fibers with diameters as small as 1 nanometer. The process involves applying a high voltage to a polymer solution or melt, which is extruded through a spinneret to form fibers that are deposited onto a grounded collector. Key parameters that affect fiber morphology include solution properties like concentration and viscosity, as well as process parameters like voltage, flow rate, and working distance. Electrospinning can be used to produce a variety of nanofibers from polymers, ceramics, and composites for applications like filtration, energy storage, and tissue engineering. Scale-up methods involve using multiple spinnerets or continuous systems like rotating drums to produce

1. Electrospinning: A nanofiber
Fabrication Technique
Ali Abbasi
R&D Manager
ProgeneLink Sdn. Bhd.
ali.abbasi@progenelink.com

2. Nanotechnology
 NANO: is derived from Greek
Meaning “DWARF”
 In 1960, it was officially confirmed
as scale standard meaning 10−9 .
 1 nm means 1 billionth of a meter.

3. Definition
 NNI defines Nanotechnology as:
“science, engineering, and
technology conducted at the nanoscale,
which is about 1 to 100 nanometers”

4. Scale Comparison

5. Nanostructures
Dimension
s
Criteria Examples
0D all dimensions in the scale.
Nanoparticles,
quantum dots,
1D
1 dimension outside the
nanoscale.
Nanofibers,
Nanowires, nanorods,
nanotubes
2D
2 dimensions outside the
nanoscale.
Coatings, thin-film-
multilayers
3D
3 dimensions outside the
nanoscale.
Bulk nanoporous
materials

6. Nanoparticles
60 nm standard Gold Nanoperticles

7. Quantum Dots
semiconductors that are small enough to exhibit quantum mechanical
properties.

8. Nanowires

9. Nanotubes
Specific strength: 48000 kN.m/kg
more than 300 times higher than that of
high-carbon steel (154 kN.m/kg)

11. Nanocoating

12. fibers with diameter between 1 and 100 nm.
12
Nanofibers (250 nm)
Human Hair (75000 nm)
diameter of grass: 0.5 cm
diameter of trees: 30 cm
Nanofibers

13. Length
(mm)
Diameter
(roughly)
Volume
(mm3)
Surface area
(mm2)
A Human Hair 1000 75000 nm 1.4 235
A nanofiber 1000 250 nm 1.5×10-5 0.78
1 hair can produce about 100000 nanofibers with 250 nm in diameters
100000 nanofibers have 78000 mm2 surface area (333 times higher).
A comparison
13

14. 14
Nanofibers
Dependence of
Specific Surface
Area on fiber
diameter

15. Nanofibers
•Polymer nanofibers: including synthetic
polymer (PAs, PS,…) natural polymer (silk,
peptides, proteins, polysaccharides, …)
•Carbon nanofibers: produced by thermal
treatments of polymeric nanofibers
•Ceramic Nanofibers: produced by calcination
of polymeric nanofibers having ceramic
precursors
For all, we need polymeric nanofibers,
first.
15

16. Main Methods of nanofibers production
Template Synthesis
Phase Separation
Self-Assembly
Melt blown
Force-spinning
Electrospinning (Melt and solution)
16

17. Electrospinning

18. Electrospinning Jet
polyvinyl alcohol fiber being electrospun from a
Taylor cone

19. Electrospraying & Electrospinning

20. Reneker et al Polymer 2008
Electrospinning Jet
20

21. Jet Instability (Bending)
An image of
electrospinning jet with
camera exposure time of
16.7 ms.
An image of
electrospinning jet with
camera exposure time of
1ms

22. Jet Instability (Bending)

23. Synthetic polymers

24. Biopolymers

25. Electrospinning Parameters
There are 3 kinds of parameters
affecting electrospun nanofibers
properties:
1. Solution Parameters
2. Process parameters
3. Ambient Parameters

26. Different structural regimes during bead-fiber transition of polystyrene
electrospun from DMF. (a) beads only, (b) beads with incipient fibers, (c) bead-
on-string, and (d) bead-freefibers.
A thesis by Eda WORCESTER POLYTECHNIC INSTITUTE 2006
26
Solution Parameters
Concentration

27. SEM photographs of electrospun nanofibers from different
polymer concentration solutions.
Viscosity
27
Solution Parameters

28. SEM photographs of 5 wt. % chitosan nanofiber in acetic acid
solution mat with different molecular weight: (a) low molecular
weight (b) high molecular weight
molecular weight
28

29. Surface tension
In a fixed concentration, with reducing the surface
tension of the solution, beaded fibers can be
converted into smooth fibers.

30. Conductivity
when a small amount of salt or polyelectrolyte is added to the solution, the
increased charges carried by the solution will increase the stretching of
the solution.
As a result, smooth fibers are formed which may otherwise yield beaded
fibers. The increased in the stretching of the solution also will tend to yield
fibers of smaller diameter.
30

31. the affection of the applied voltages on the diameter of electrospun
fibers is a little controversial.
Effect of voltage on
morphology and fiber
diameter distribution
from a 7.4 wt. %
PVA/water solution (DH =
98 %, tip–target distance
= 15 cm, flow rate = 0.2
ml/h). Voltages a) 5; b )
8; c )10; and d ) 13 kV.
31
Voltage

32. 32
Voltage

33. SEM images of the electrospun PSF fibers from 20 wt. %
PSF/DMAC solution at 10 kV with different distances. The
distances of A and B are 10 and 15 cm, respectively.
33
Working distance
Minimum distance is required for electrospinning

34. Types of collector
 Shape and movement of collector affects
fiber morphology
Feeding or flow rate
 Increase in fiber D with increase in flow
rate
 Too high flow rates: Bead generation
Humidity
 High: formation of circular pores on the
fibers
Temperature
 Decrease in fiber D with increasing T

35. Electrospinning Parameters
The effect of electrospinning parameters on fiber diameter and morphology
Solution parameters
parameter effect
Viscosity Low: Bead formation; high: Increasing fiber diameter, disappearance of beads
Solution concentration increasing fiber diameter with increasing concentration
Molecular weight decrease in the number of beads and droplets with increasing molecular weight
Conductivity conductivity increase leads to a decline in fiber diameter
Surface tension
No inclusive correlation with fiber morphology; instability of jets with surface tension
increase
Process Parameters
Applied voltage fiber diameter reduction with voltage increment
Tip-to-collector distance
formation of beads with very small and very large distances; minimal spacing is
necessary for uniform fibers
Flow rate smaller fibers for lower flow rates; bead formation for very high flow rates
Ambient Parameters
Temperature Temperature increase leads to smaller fibers
Humidity Formation of circular pores in very high humidity

37. Apparatus used in electrospinning technique:
1. Syringe, containing polymer or
composite solution
2. Injection Pump (syringe pump)
3. High voltage power supply
4. Metallic needle with an orifice at the
tip
5. Collector electrode

38. Injection Systems &
Needles
38

39. 39

40. 40

41. EFFECTS OF NOZZLE DIAMETER

42. Core Shell Fibers
Core:
non-biocompatible materials
Non-electrospinnable materials
Core-shell fibers typically are bi-component fibers consisting of a
core of one material and an encapsulating shell of another material.
Coaxial Electrospinning

44. Multicomponent Electrospun Fibers

45. Collectors
45

46. PLATE COLLECTOR
Useful for optimization of spinning
conditions and creation of a small
amount of sample

47. There are two circles of nanofiber mats.
Form center to outside of the circle the
content of nanofibers is reduced so non-
homogen mats will be formed in this type
of collector.

50. Edge type collector
Grid type collector

51. Roll to Roll COLLECTOR
It is a collector who can make the
Nano fiber sheet of 10 m×20 cm
with the LAB machine.

52. Parallel collector
The positioning of the collector
affects fiber deposition.

53. 53
Fabrication of Aligned Fibrous
Arrays by Magnetic
Electrospinning

54. Continuous Electrospinning of Aligned Polymer
Nanofibers onto a Wire Drum Collector
Nano Letters, 2004, 4 (11), pp 2215–2218

55. disc collector

56. MANDREL COLLECTOR
For tubular nanofiber assembly
Mandrel diameter, width of fiber collecting
Attachable mandrel diameter: 0.5 to 10mm

57. 57
Template-assisted assembly
of electrospun fibers

58. 58

59. Scale-up electrospinning
59

60. Multi-needle electrospinning

61. multineedle electrospinning
schematic and photograph of a multi-nozzle spinning head that being
commercialized. The device uses upwards direction of electrospinning in
order to eliminate polymer droplets eventually falling on the substrate.

64. Needleless
Electrospinning
Recently, needleless electrospinning appeared as an
alternative electrospinning technology with the aim of producing
nanofibers on a large scale from a compact space.

65. Schematic summary
of needleless rotating
spinnerets
(electrospinning
direction along the
red arrow).

66. electrospinning setup using a
rotating roller

67. a needleless electrospinning
system
using a rotary cone

69. Needleless Electrospinning

72. coil spinneret

74. Wire spinneret

75. Wire spinneret