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256 13. MULTIDIMENSIONAL BIOMECHANICS APPROACHES

FIG. 13.1 Schematic representation of the (A) mechanoelectric properties of a scaffold upon the application of mechanical stimuli. (B) and
(C) magnetoelectric properties of scaffolds upon the application of magnetic stimulus.

Therefore materials able to induce a surface electrical charge are able to stimulate the growth of cells and tissues in
culture constituting a suitable approach for tissue engineering applications. Examples of such materials are the mate-
rials possessing mechanoelectric, magnetic, and magnetoelectric properties. Mechanoelectric materials are mostly con-
stituted by piezoelectric materials that respond to mechanical stimuli, inducing an electrical potential variation
(Fig. 13.1A). Magnetic and magnetoelectric materials used for tissue engineering applications are mainly composites
comprising magnetic or magnetostrictive particles and a piezoelectric polymer. Due to their magnetic component, they
sense a magnetic field that induces a mechanical stimulation on the scaffold due to the incorporated magnetic or mag-
netostrictive properties, which further induce an electrical polarization variation due to the piezoelectric phase present
in the same scaffold (Fig. 13.1B and C).

13.3 ELECTRIC AND ELECTROMECHANICAL CLUES

New advances in tissue engineering have been carried out based on the application of different kind of stimuli (elec-
tric and/or mechanical) to influence cell response and fate [62]. Table 13.1 summarizes relevant experimental works
where electrical and/or mechanical stimuli were used.
Some studies rely on the application of electrical or mechanical stimuli without the use of active polymers (such
as conductive or piezoelectric). However, in the previous years, active polymers have been used for different tis-
sue engineering areas (such as bone, muscle, and nerve) to induce these stimuli more naturally, resembling and
taking advantage of the presence of electrical or mechanical signals within the body. For example, neurite out-
growth was significantly improved when conductive polymer was electrically stimulated (Fig. 13.2). Also, there
are tissues that improve differentiation with the combination of electrical and mechanical stimuli, as in the case of
the muscle.
Piezoelectric polymers such as poly(vinylidene fluoride) (PVDF) and vinylidene fluoride (VDF) copolymers are the
most widely researched polymers to develop scaffolds with mechanoelectric properties [63]. These polymers possess

II. MECHANOBIOLOGY AND TISSUE REGENERATION