Biomedical Engineering Reference
In-Depth Information
hydrophilic surfaces have also been proven not to affect the antibacterial property. Besides
surface energetics and its interaction with proteins and microbes, surface topography can
play an important role as well. Generally, an ultrasmooth and ultralow porosity film is
desired. Doping with known antibacteria elements can drastically improve bactericidal
activity. This is one good example of the amorphous nature of the material where tuning
and moderation is flexible.
There are already a number of application-specific studies. Coronary stents and other
vascular stents have received great attention. Commercial products incorporating propri-
etary amorphous carbon coatings have been available for many years. Another promising
application is orthopedic implants, where the biocompatibility and mechanical proper-
ties, such as high hardness and low friction, come together to reduce wear and failure.
However, results have been contradicting. The conflicting results may be caused by dif-
ferent regimes used in the tests and simulation of actual physiological conditions. Human
inner space is a harsh and unforgiving environment with a condition difficult to replicate
in vitro.
Although much attention has been received and many studies have been done, the actual
numbers of commercially available products that are useful in improving human life still
only number a handful. Even so, these are good indicators of the potential amorphous car-
bons have. More work with good results, especially clinically, needs to be achieved before
the material can be widely recognized and live up to its potential for widespread use.
References
[1] S. Aisenberg, R. Chabot: Ion-beam deposition of thin films of diamond-like carbon.
J. Appl.
Phys.
42 (1971) 2953.
[2] G. Galli, R.A. Martin, R. Car, M. Parrinello: Structural and electronic properties of amorphous
carbon.
Phys. Rev. Lett.
62 (1989) 555.
[3] N.A. Marks, D.R. McKenzie, B.A. Pailthorpe, M. Parrinello: Microscopic structure of tetrahe-
dral amorphous carbon.
Phys. Rev. Lett.
76 (1996) 768.
[4] Y. Lifshitz, S.R. Kasi, J.W. Rabalais: Subplantation model for film growth from hyperthermal
species: Application to diamond.
Phys. Rev. Lett.
62 (1989) 1290.
[5] Y. Lifshitz, S.R. Kasi, J.W. Rabalais, W. Eckstein: Subplantation model for film growth from
hyperthermal species.
Phys. Rev. B
41 (1990) 10468.
[6] W. Moller: Modeling of the
sp
3
/
sp
2
ratio in ion beam and plasma-deposited carbon films.
Appl.
Phys. Lett.
59 (1991) 2391.
[7] H.J. Steffen, S. Marton, J.W. Rabalais: Displacement energy threshold for Ne
+
irradiation of
graphite.
Phys. Rev. Lett.
68 (1992) 1726.
[8] J. Koike, D.M. Parkin, T.E. Mitchell: Displacement threshold energy for type IIa diamond.
Appl.
Phys. Lett.
60 (1992) 1450.
[9] D.R. McKenzie, D. Muller, B.A. Pailthorpe: Compressive-stress-induced formation of thin-film
tetrahedral amorphous carbon.
Phys. Rev. Lett.
67 (1991) 773.
[10] J. Robertson: Deposition mechanisms for promoting sp
3
bonding in diamond-like carbon.
Diamond Rel. Mater.
2 (1993) 984.
[11] J. Robertson: The deposition mechanism of diamond-like a-C and a-C:H.
Diamond Rel. Mater.
3
(1994) 361.
[12] S. Uhlmann, T. Frauenheim, Y. Lifshitz: Molecular-dynamics study of the fundamental pro-
cesses involved in subplantation of diamondlike carbon.
Phys. Rev. Lett.
81 (1998) 641.
