Information Technology Reference
In-Depth Information
12.1. INTRODUCTION
12.1.1. Molecules: Nanoscale and Computing
Living organisms can be considered as information processing entities designed
on the base of molecules (among other views). Taking a closer look at the
information processing capacities of living beings, it becomes clear that their
performances are (still) superior to that of silicon-based devices. This advantage
is basically founded on design principles involving, in particular, massive
parallelism, high integration depth, and network-like organization (e.g., brain,
nerve cells, receptors, recognition schemes); all implicating molecules. However,
the difficulties in mastering the built-in complexity set the main obstacle for in the
emergence of purely molecularly and biologically based computing devices. First,
rational steps moving along this tempting road map have raised considerable
interest, mainly using DNA molecules as structural and functional base (see also
Chapter 13) [1]. At this point, it has to be mentioned that the herein reviewed field
of molecular computing is still in its early infancy and so marked by several
teething problems, e.g., the need for a complete redesign of the communication
interface with the environment and the still widely unexplored integration of
molecules into electrical circuits. In addition, the use of basic building blocks of
living systems in technological devices raises moral and ethical questions, which
have to be addressed in parallel with the progressing scientific development of
the field.
The use of molecular concepts is not only restricted to biological material.
Beyond this scope, the introduction of simpler, organic molecules into already
established information processing paradigms of silicon technology seems to be an
attractive trade off. Driven by the recent emergence and massive application of
new technologies working at the lower nano-regime, a length scale which matches
perfectly with the intrinsic size of organic molecules, is a concept that seems to be a
possible shortcut for the device development of the nearer future.
Throughout this chapter, the term ''biologically inspired'' will be used in the
sense that it stands for the involvement of molecules in both conventional and
advanced information processing schemes (e.g., storage, logic operations, bist-
ability). The use of molecular units within information processing algorithms and
devices represents herein the introduction of molecules into the nanoworld; these
units can be addressed selectively by applying suitable techniques and methods
exhibiting nanometer resolution (e.g., scanning probe techniques). For this to
occur, several premises have to be fulfilled on the molecule side: The (i) molecular
components have to possess a physical switching property (e.g., redox, magnetic,
and/or spin state transitions), and (ii) their geometry should enable a smooth
arrangement in two-dimensions (2D) in order to warrant (iii) precise addressing of
the single molecule components. The degree of fulfilment of these premises will set
the stage for the successful integration and implementation of molecular switching
units into nanostructured or even nanoscaled devices. Thus, device architectures
possessing addressable nanopatterned switching units promise to serve as
 
Search WWH ::




Custom Search