Biomedical Engineering Reference
In-Depth Information
computer control instead of control by a human operator, in his 1986 topic
Engines of Creation: The
Coming Era of Nanotechnology
, to popularize the potential of nanotechnology.
Since then several definitions of nanotechnology have evolved. For example, the dictionary
1
def-
inition states that nanotechnology is “the art of manipulating materials on an atomic or molecular
scale especially to build microscopic devices.” Other definitions include the US government
2
which
state that “Nanotechnology is research and technology development at the atomic, molecular, or mac-
romolecular level in the length scale of approximately 1-100 nm range, to provide a fundamental
understanding of phenomena and materials at the nanoscale and to create and use structures, devices,
and systems that have novel properties and functions because of their small and/or intermediate size.”
The Japanese
3
have come up with a more focused and succinct definition. “True Nano”: as nano-
technology which is expected to cause scientific or technological quantum jumps, or to provide great
industrial applications by using phenomena and characteristics peculiar in nano-level.
Regardless of the definition that is used it is evident that the properties of matter are controlled
at a scale between 1 and 100 nm. For example, chemical properties take advantage of large surface
to volume ratio for catalysis, interfacial and surface chemistry is important in many applications.
Mechanical properties involve improved strength hardness in light-weight nanocomposites and nano-
materials, altered bending, compression properties, nanomechanics of molecular structures. Optical
properties involve absorption and fluorescence of nanocrystals, single photon phenomena, and pho-
tonic band-gap engineering. Fluidic properties give rise to enhanced flow using nanoparticles and
nanoscale adsorbed films are also important. Thermal properties give increased thermoelectric perfor-
mance of nanoscale materials, interfacial thermal resistance important.
1.2
NANOTECHNOLOGY APPROACHES
Numerous approaches have been utilized successfully in nanotechnology and as the technology
develops further approaches may emerge. The approaches employed thus far have generally been
dictated by the technology available and the background experience of the researchers involved.
Nanotechnology is a truly multidisciplinary field involving chemistry, physics, biology, engineer-
ing, electronics, social sciences, etc., which need to be integrated together in order to generate the
next level of development in nanotechnology (
Figure 1.1
). Fuel cells, mechanically stronger materi-
als, nanobiological devices, molecular electronics, quantum devices, carbon nanotubes, etc. have been
made using nanotechnology. Even social scientists are debating ethical use of nanotechnology.
The two main approaches in order to explain nanotechnology to the general public have been
oversimplified and have become known as the “top-down” approach. This involves fabrication of
device structures via monolithic processing on the nanoscale. This approach has been used with
spectacular success in the semiconductor devices used in consumer electronics. The “bottom-up”
approach involves the fabrication of device structures via systematic assembly of atoms, molecules,
or other basic units of matter. This is the approach nature uses to repair cells, tissues, and organ sys-
tems in living things and indeed for life processes such as protein synthesis. Tools are evolving which
1
Miriam Webster dictionary 2010.
2
US Government
www.nano.gov.
3
K. Shimizu, INC 2, USA (2006).
