Biomedical Engineering Reference
In-Depth Information
16
Electroactive Polymers as
Smart Materials with Intrinsic
Actuation Properties: New
Functionalities for Biomaterials
Federico Carpi and Danilo De Rossi
CONTENTS
16.1 Introduction .........................................................................................................................
483
16.2 Electroactive Polymers........................................................................................................
485
16.3 Polymer Gels .......................................................................................................................
486
16.4 Ionic Polymer-Metal Composites .......................................................................................
489
16.5 Conducting Polymers ..........................................................................................................
490
16.6 Dielectric Elastomers ..........................................................................................................
496
16.7 Conclusions..........................................................................................................................
498
References ......................................................................................................................................
498
16.1 INTRODUCTION
The i eld of biomaterials is very broad. As largely discussed in this topic, a biomaterial is typically
conceived as a biocompatible and bioapplicable synthetic material, which is employed either to
replace a part of a living tissue or to function in intimate contact with it. Accordingly, biomaterials
are intended to interface with biological systems in order to evaluate, treat, augment, or replace bio-
logical functions of tissues or organs of the body. The rapidly growing basic science of biomaterials,
along with continuous improvements on their fabrication and processing, provides fundamental
benefi ts for medical devices that already use biomaterials in clinical practice, such as artifi cial hips,
oral implants, vascular stents, drug delivery systems, etc.
The functional properties of each biomaterial are, of course, the key elements that determine
its suitability for a specifi c application. As an example, both the structural support function and
the interface properties with living bone offered by calcium hydroxylapatite coatings are vital for
bone replacement implants. Likewise, surface functionalization (e.g., by plasma processing) is used
to graft surface functional groups, so as to transform a bioinert material into a bioactive structure.
Nowadays, such types of functional properties are largely studied and represent one of the biggest
areas of investigation of the biomaterials science. On the contrary, another class of functional proper-
ties, the actuation properties that are potentially useful for several applications, are considerably less
studied. Accordingly, this chapter intends to provide a brief survey on the classes of materials that
could be employed for this purpose, along with the applications that could benefi t from their use.
Actuation can be defi ned as a property shown by a material or a mechanism by which it is able
to act upon its external environment by transducing a certain form of input energy into an external
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