Biomedical Engineering Reference
In-Depth Information
integrating thin-film sensors with today's microelectronics. This can be
realized by depositing thin films of this material onto suitable substrates.
This not only allows miniaturization of the sensor elements, as dictated by
technological demands for smaller and smaller electrical components, but
also enables the same microfabrication technologies to be used in
production of both electronic and magnetic devices especially for applica-
tions like MEMS, NEMS, etc. This makes it commercially more attractive
because of the reduced costs and the applicability to a wider range of
systems.
2.9
Applications: assembly of magnetic
nanostructures
Arrays of magnetic nanostructures can find applications in high-density
recording media and magnetic random access memory (MRAM). An
important challenge is to assemble these magnetic nanostructures in an
effective and controllable way. Several strategies have been developed for
the growth of nanostructured magnetic materials, including nanolithogra-
phy-based methods, solution-based approaches and template-based meth-
ods. Some of these methods, however, require high temperatures and special
conditions, while in other cases they demand complex and time-consuming
procedures. For instance, in template-assisted growth of nanostructures, the
selection of suitable catalysts and templates is not straightforward, and the
removal of templates and the stabilization of unsupported nanostructures
are crucial issues that may compromise the structural and physical
properties. The ability to create ordered arrays of well-defined and periodic
nanostructures in an accurate, fast and inexpensive fashion would be of
great interest for future applications.
The hierarchical self-assembly of nanoscale building blocks (nanoclusters,
nanowires, nanobelts and nanotubes) is a technique for building functional
electronic and photonic nanodevices. Fractal structures are common in
nature across all length scales - from self-assembled molecules, to the shapes
of coastlines, to the distribution of galaxies and even to the 3D shapes of
clouds. On the nanoscale, dendritic fractals are one type of hyperbranched
structure that are generally formed by hierarchical self-assembly under non-
equilibrium conditions. Investigation of hierarchically self-assembled fractal
patterns in chemical systems has shown that the distinct size, shape and
chemical functionality of such structures make them promising candidates
for the design and fabrication of new functional nanomaterials, but it is
challenging to develop simple and novel synthetic approaches for building
hierarchically self-assembled fractal architectures of various systems (see
Fig. 2.9 and Fig. 2.10).
