Biomedical Engineering Reference
In-Depth Information
1.3
Nanotechnology on a large scale and volume
Nanotechnology is being researched extensively internationally, and governments and research
organizations are spending large amounts of money and human resources on nanotechnology. This
has generated interesting scientific output and potential commercial applications, some of which
have been translated into products produced on a large scale. However, in order to realize commer-
cial benefits far more from lab-scale applications need to be commercialized, and for that to happen
nanotechnology needs to enter the realm of nanomanufacturing. This involves using the technolo-
gies available to produce products on a large scale, which is economically viable. A nanomanufac-
turing technology should be:
capable of producing components with nanometer precision,
able to create systems from these components,
able to produce many systems simultaneously,
able to structure in three dimensions,
cost-effective.
1.3.1
Top-down approach
The most successful industry utilizing the top-down approach is the electronics industry. This
industry is utilizing techniques involving a range of technologies such as chemical vapor deposition
(CVD), physical vapor deposition (PVD), lithography (photolithography, electron beam, and X-ray
lithography), wet and plasma etching to generate functional structures at the micro- and nanoscale
(
Figure 1.1
). Evolution and development of these technologies have allowed the emergence of
numerous electronic products and devices that have enhanced the quality of life throughout the
world. The feature sizes have shrunk continuously from about 75
m to below 100 nm. This has
been achieved by improvements in deposition technology and more importantly due to the develop-
ment of lithographic techniques and equipment such as X-ray lithography and electron beam
lithography.
Techniques such as electron beam lithography, X-ray lithography, and ion beam lithography,
all have advantages in terms of resolution achieved; however, there are disadvantages associ-
ated with cost, “optics,” and detrimental effects on the substrate. These methods are currently
under investigation to improve upon current lithographic processes used in the integrated
circuits (IC) industry. With continuous developments in these technologies, it is highly likely
that the transition from microtechnology to nanotechnology will generate a whole new genera-
tion of exciting products and features.
A demonstration of how several techniques can be combined together to form a “nano” wine
glass (
Figure 1.2
). In this example, a focused ion beam and CVD have been employed to produce
this striking nanostructure.
The top-down approach is being used to coat various coatings to give improved functionality.
For example, vascular stents are being coated using CVD technology with ultrathin diamond-like
carbon coatings in order to improve biocompatibility and blood flow (
Figure 1.3
). Graded a-SixCy:
H interfacial layers results in greatly reduced cracking and enhanced adhesion.
µ