Page 15 - Nanotechnology an introduction

Section 2.7). This is usually because, for a given probability of occurrence of defects per unit volume, a smaller volume will inevitably contain fewer
defects. This advantage may be countered if the surface itself is a source of defects because of the increased preponderance of surface (Section
2.2).
Fabrication procedures may also be enhanced by miniaturization: any moving parts involved in assembly will be able to operate at much higher
frequencies than their macroscopic counterparts. New difficulties are, however, created: noise and surfaces. The random thermal motion of atoms
plays a much more deleteriously influential role than at the macroscale, where it can normally be neglected. The concept of the eutactic environment
was introduced partly to cope with this problem. Bottom–up self-assembly, of course, requires noise to drive it; it is amplified up to constructive
macroscopic expression by virtue of special features of the components being assembled. The preponderance of surfaces at the nanoscale, which
can act as attractors for contamination and so forth, is probably best solved by appropriate energetic engineering of the surfaces (Section 3.2).

1.5.3. A Universal Fabrication Technology
Such a technology is usually considered to be based on nanoscale assemblers (i.e., personal nanofactories). They would enable most artifacts
required by humans to be made out of a simple feedstock such as acetylene together with a source of energy (see Section 8.3). Note that there is
an intermediate level of technological achievement in which objects are constructed with atomic precision, but without the need for construction
equipment to be itself in the nanoscale (e.g., using current tip-based ultramicroscope technology and its derivatives). Nanofabrication
(nanomanufacture or nanofacture) represents the ultimate in modularity. Using nanoblocks, purity, the bane of specialty chemical manufacturing,
especially pharmaceuticals, is no longer as issue—extraneous molecules are simply ignored by the fabrication system.
1.6. Summary
Nanotechnology is defined in various ways; a selection of already published definitions is given, from which it may be perceived that a reasonable
consensus already exists. A more formal concept system is developed, in which care is taken to use the terms consistently. Nanotechnology is also
defined ostensively (i.e., what objects already in existence are called “nano”?) and by its history. The role of biology is introduced as providing a
living proof-of-principle for the possibility of nanotechnology; this has been of historical importance and continues to provide inspiration. Motivations
for nanotechnology are summarized.
1.7 Further Reading
Broers, A.N., Limits of thin-film microfabrication, Proc. R. Soc. Lond. A 416 (1988) 1–142.
Drexler, K.E., Engines of Creation. (1986) Anchor Books/Doubleday, New York.
Drexler, K.E., Nanosystems: Molecular Machinery, Manufacturing, and Computation. (1992) Wiley-Interscience.
Maruyama, K.; Nori, F.; Vedral, V., The physics of Maxwell's demon and information, Rev. Mod. Phys. 81 (2009) 1–23.
Ostwald, W., Die Welt der vernachlässigten Dimensionen. (1914) Steinkopff, Dresden.
Zsigmondy, R.; Thiessen, P.A., Das kolloide Gold, Akademische Verlagsgesellschaft. (1925) Leipzig.