Electrospun Nanofibers for Regenerative Medicine - Soft Fibrillar Materials: Fabrication and Applications - page 267

(a)

Mechanical

(b)

(c)

Electrostatic

(d)

(e)

Magnetic

S N

Figure 9.3 Controlling the alignment of
electrospun nanofibers using three different
forces: (i) mechanical forces through the use
of a rotating mandrel (a); (ii) electrostatic
forces through the use of a metallic staple
(b), a metallic ring with a metallic pin in the
center (c), and an array of metallic beads
(d); and (iii) magnetic forces through the
use of a pair of permanent magnets (e). The

SEM images in the right column show typ-
ical morphologies of the aligned nanofibers
collected using the different methods. The
yellow plates are grounded conductive elec-
trodes. Reproduced with permission: (c)
from Ref. [68], copyright 2010 American
Chemical Society; (d) from Ref. [69], copy-
right 2011 Wiley-VCH; and (e) from Ref. [70],
copyright 2010 Wiley-VCH.

A number of methods have been developed for controlling the alignment of elec-
trospun nanofibers. These methods can be categorized into three major categories
depending on the type of forces involved (Figure 9.3): mechanical, electrostatic,
and magnetic. These methods are described in the subsequent sections.

9.3.1
Alignment Caused by Mechanical Forces

In order to align nanofibers using mechanical forces, a metallic rotating mandrel
is often used as the collector (Figure 9.3a). When the electrospun nanofibers are