Biomedical Engineering Reference
In-Depth Information
CHAPTER 6
Biomaterials
6.1 Overview
Various materials are utilized in a wide spectrum of medical applications (Figure
6.1)
.
Biomaterials form the critical components of every biomedical application.
Cotton pads are used to stop bleeding of minor cuts within a few minutes, poly-
meric catheters are used to feed nutrients or therapeutic molecules, stainless steel
surgical tools are used to operate on a person, and composite total hip replacement
devices are used with the intention of lasting for 10 to 15 years or the lifetime of
the patient. The extent of material interaction with the body varies with the type of
application, either with different cells, tissues, or extracellular fluids in addition to
the duration. Apart from understanding the mechanical property requirements (dis-
cussed in Chapter 5), the design of many biomedical devices requires the processing
of materials to the required dimensions and the global acceptance of the material by
the surrounding tissues and fluids of the body and by the body as a whole. Process-
ing and fabrication of components could affect the dimensional stability, surface
characteristics, and surface chemistry/physics. In many cases, the blood interactions
required within a device create fluid eddies and tissue damage that are favorable to
blood clotting with grave clinical consequences in the absence of an anticoagulant.
Advancements in material and manufacturing technologies have endowed
products with much greater reliability and reproducibility. Polymeric materials are
used as contact lenses and biodegradable sutures; contact lenses are designed to
interact with tissues minimally for a few hours to weeks, whereas sutures are de-
signed to slowly resorb over a few weeks to months and continuously exposed to
the wound healing process. As the basis for biomaterials selection design advances,
tailoring biomaterial properties for individual applications becomes a practical
means of improving implant safety and efficacy. This chapter aims to establish a
fundamental understanding of and appreciation for the selection, development,
and performance of the many types of biomaterials used in medicine and medical
devices. First, different types of biomaterials utilized in medical applications and
their material characteristics with the focus on common problems and importance
of surface topographies are discussed. Next, the basic biological interactions such
as blood protein adsorption, inflammatory reaction, and infection are discussed.
Finally, the use of biomaterials in the context of tissue engineering is discussed.
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