Biomedical Engineering Reference
In-Depth Information
21.6.1 Substrates
688
21.6.2 TiN Coating Process
688
21.7
Coating Characterization
688
21.7.1 Surface Roughness Estimation
688
21.7.2 Adhesive Wear Characteristics
689
21.7.3 Abrasive Wear Characteristics
690
21.7.4 Coating Adhesion Studies
692
21.7.5 Microhardness Measurements
693
21.7.6 Simulated Accelerated Durability Studies
695
21.8
Biological Characterization
697
21.8.1 Cytotoxicity
698
21.8.2 Hemocompatbility
698
21.8.3 Tissue Compatibility
699
21.8.4 Large Animal Experiments
700
21.9
Potential Applications
702
21.10 Future Perspective
703
Acknowledgments
703
References
704
21.1 OVERVIEW
In the current era, the management of cardiovascular diseases is substantially
infl uenced by the research and development in biomaterials. At the same time,
the choice of materials intended for this segment has been the most diffi cult
owing to the stringent requirements of blood compatibility. This has led to the
researchers look towards surface coatings., The substrate material can be chosen
to provide the required strength for structural integrity, while coatings can
be employed to enhance the blood compatibility. Titanium Nitride (TiN) and
Diamond Like Carbon (DLC) are two such ceramic coatings that seem to offer
excellent prospects.
Both DLC and TiN exhibit similar properties such as hardness, low frictional
coeffi cient, high wear and corrosion resistance, chemical inertness, and very good
processability. Both coatings can be polished to a high level of surface fi nish,
which is an important parameter in blood contacting applications. Both exhibit
very good tissue and blood compatibility and are well tolerated in biological envi-
ronments. This chapter looks at the processing, characterization, and applications
of TiN and DLC coatings, with a focus on cardiovascular applications.
21.2 CARDIOVASCULAR DEVICES
In no area of medical practice have synthetic biomaterials played a more
critical role than in the cardiovascular system [Ratner 2004]. Cardiopulmonary
bypass with the help of oxygenators and pumps have made possible open heart
surgeries. Artifi cial heart valves are used to replace damaged or diseased natural
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