Functional Microstructures by Self-Assembly - Molecular Self-Assembly: Advances and Applications - page 384

key strength of self-assembly is its ability to integrate different
types of components into one unit. In this area, it can outperform
conventional assembly technologies and may represent an avenue
to affordable fabrication of hybrid microstructures.
Self-assembly processes can be divided into two broad categories,
based on the scale of the components that are being assembled.
Microscale self-assembly operates with component dimensions of
1 m, whereas in nanoscale self-assembly the dimensions

lie in the 1

−

1000

µ

−

1000 nm range. Owing to the difference in component
size, the two processes utilize different phenomena to manipulate
components.
Microscale processes typically rely on shape recognition as a
means of homing, and capillary or gravitational forces for docking
and securing the assembled parts in place. Such a principle works
well for geometric microscale components, typically prepared by
microfabrication techniques. Nanoscale processes are quite different,
as they handle components of molecular dimensions and rely on
electrostatic interactions, molecular affinity, or covalent chemical
reactions both for component homing and securing.
Molecular assembly on the nanoscale has been studied and
utilized by surface scientists for over a century. A good example of
“classical” nanoscale self-assembly is the automatic organization
of detergent molecules at an oil

water interface. Microscale self-
assembly, however, is a much more recent concept. This is because
modern-day fabrication methods are required to produce microscale
components, as well as microscale assembly templates.
Despite the differences in their component attachment
mechanisms and dimensions, microscale and nanoscale self-
assembly share a common operational principle: Both processes can
generate functional units from a diverse collection of nonfunctional
components. In addition, the two scale domains are quite often
utilized in the same process, with nanoscale techniques providing
ways to attach and functionalize microscale components. This review
has been written to illustrate this interconnectivity and synergy by
describing several different self-assembly processes on different
size scales.
The review first introduces the fundamentals of nanoscale
assembly, by discussing the mechanism of protein binding on metal
substrates. This chapter illustrates how nanoscale self-assembly
can be controlled by experimental variables, and how a functional

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