Biomedical Engineering Reference
In-Depth Information
Polymer solution
Polymer solution
(a)
(b)
Polymer solution
Polymer solution
(c)
(d)
Figure 14.4
Cartoon.representations.of.four.techniques.to.align.nanoibers.during.electrospinning:.(a).cylinder.collectors,.(b).
auxiliary.electrodes/electric.ields,.(c).thin.wheels,.and.(d).frame.collectors.
Huang. et. al.. 2003).. Another. advantage. of. this. technique. is. that. individual. nanoibers.
can. be. obtained. with. a. distance. between. two. ibers. being. 1-2.μm.. This. phenomenon. is.
explained.by.the.fact.that.the.nanoibers.retain.suficient.residual.charges.before.reaching.
the.electrically.ground.target.(Theron.et.al..2001,.Huang.et.al..2003)..Thus,.once.a.nanoiber.
adheres.to.the.edge.of.the.wheel.it.will.repel.the.next.nanoiber.that.has.an.attraction.to.
this. edge,. resulting. in. suficient. spacing. between. subsequent. nanoibers.. A. more. recent.
technique.to.align.ibers.is.the.use.of.a.frame.collector.(Huang.et.al..2003,.Tan.et.al..2005)..
Basically,.a.frame.is.placed.under.the.spinning.jet..Huang.et.al..determined.that.the.material.
of.the.frame.affected.the.alignment.of.the.nanoibers.by.testing.an.aluminum.frame.with.a.
wooden.frame..They.determined.that.the.aluminum.frame.resulted.in.preferable.nanoiber.
alignment.when.compared.with.the.wooden.frame..Another.approach.that.builds.off.of.
this. concept. is. the. use. of. parallel-grounded. plates. to. form. aligned. nanoibers. (Li. et. al..
2003)..This.is.a.very.simple.method.where.strips.of.electrical.conductors.are.placed.apart.
from.each.other.under.the.spinning.jet.(Li.et.al..2003)..Due.to.electrostatic.interactions,.the.
ibers.will.be.stretched.across.the.gap.to.form.a.parallel.array.
14.3 Characterization of Electrospun Nanofibers
14.3.1 Morphology and Diameters of Nanofibers
Analysis. of. the. morphology. and. diameters. of. nanoibers. can. be. performed. using. scan-
ning. electron. microscopy. (SEM),. transmission. electron. microscopy. (TEM),. and. atomic.
force.microscopy.(AFM).
