Overview

Molecular Manufacturing is the construction of atomically-precise macroscale products. It does not require the manufacturing process to be computer-controlled at every step or to handle atoms individually, nor does it require the chemical processes to be limited to mechanosynthesis; only the finished product must be machine-phase.

Molecular Manufacturing is often used a synonym of 'Molecular Nanotechnology', the vision of nanotechnology started by Eric Drexler and further explored by Ralph Merkle, Robert Freitas and Zyvex.. While Molecular Nanotechnology is centered around a variety of (Diamond-based) molecular machines, from the Drexler Arm (A setting in which one of these builds a copy of itself is pictured below) to the Respirocyte to the Neon Pump, manufacturing is a more global process, that concerns itself with such machines and with more global objectives, such as cheap, distributed manufacturing technologies, which is why 'molecular manufacturing' is the preferred name for this article.

Nanotechnology, in general, is the art of building practical, complex machinery with sizes varying from 100 to 1 nanometers. Nanoscience and nanotechnology are new names for the gradually, naturally extended discipline of chemistry; and so nanoscience should not be confused with the much more specific field of Molecular Nanotechnology. The machines and processes shown in this article are not filling journals or being made daily in laboratories.

How small are atoms really? Kenneth Ford says,

''"To arrive at the number of atoms in a cubic centimeter of water (a few drops), first cover the earth with airports, one against the other. Then go up a mile or so and build another solid layer of airports. Do this 100 million times. The last layer will have reached out to the sun and will contain some 1016 airports (ten million billion). The number of atoms in a few drops of water will be the number of airports filling up this substantial part of the solar system. If the airport construction rate were one million each second, the job could just have been finished in the known lifetime of the universe (something over ten billion years)."^1

History

The origins of nanotechnology, whether 'normal nanotechnology' or Molecular Nanotechnology, are often linked to Richard Feynman's historic 1959 lecture, There's Plenty of Room at the Bottom, but the origins can be traced further back. Colin Milburn in his book Nanovision, for example, correctly argues that Feynman 'merely' articulated existing ideas in the science fiction of the time.

Feynman's path to nanotechnology consisted on having remotely controlled arms building smaller ones, successively until the nanoscale. The closest parallel to this idea is Robert Heinlein's 1942 Waldo, in which a homonymous robot does this until its copies are small enough to perform sub-cellular surgery^2. A coworker at Caltech's JPL, Al Hibbs, had read the story and even filed a patent application for the use of waldoes in space exploration. He talked it over with Feynman and 'delighted' him with the notion of miniature surgical robots.^3

Mechanosynthesis of Diamondoid

Mechanosynthesis is the synthesis of chemical structures catalyzed by mechanical pressure and constraints, or, simply, the use of mechanical force to direct and alter the course of chemical reactions. For example, the animations to the left show a reversible mechanosynthethic reaction in which an acetylene dimer is placed on a diamond C(100) surface and then removed, using an atomic force microscope with a special tip geometry.

Mechanosynthesis of diamond, specifically, is the synthesis through this mechanical chemistry of diamond, a stiff polycyclic structure.

The evidence for mechanosynthesis can be traced back to the historic 1989 spelling of the IBM logo using 35 Xenon atoms in a surface of Nickel by Don Eigler and Erhard K. Schweizer. However, this experiment took place a few degrees above absolute zero, and no covalent bonds were formed.

In 2003, Oyabu et al.^4 first demonstrated mechanosynthesis on a Silicon surface using an atomic force microscope to remove an atom from the surface, then place it again on the same position, again at liquid helium temperatures.

Minimal Toolset for Positional Diamond Mechanosynthesis

The landmark paper by Ralph Merkle and Robert Freitas, published in 2008 by the Journal of Computational and Theoretical Nanoscience, shows a minimal set of tools that can be used to synthesize unstrained diamond of arbitrary size, and also synthesize copies of itself. Each tooltip is designed to work on a flat surface of (Initially) Hydrogen-terminated diamond and can be moved attached to a scanning probe microscope to control their motion. Bootstrap strategies -- Through which ordinary tools are used to produce the simplest tips, which are then used to produce the rest of the set -- are provided, along with reaction sequences for the construction of diamond and fullerene.

The paper is: Robert A. Freitas Jr., Ralph C. Merkle, "A Minimal Toolset for Positional Diamond Mechanosynthesis," J. Comput. Theor. Nanosci. 5(May 2008):760-861; and is available here.

The rapid, atomically-precise construction of macroscale objects of varied molecular structures is the eventual goal of molecular nanotechnology. The paper presents the more modest and specific objective of ultra-high-vacuum-based diamondoid mechanosynthesis using the positional control granted by an scanning probe.

Following the 1992 publication of Drexler's Nanosystems, in which some basic mechanosynthethic reaction pathways and sketches of possible tooltips, in 1997 Merkle outlined the "hydrocarbon metabolism", a set of reaction pathways for DMS, which used nine different tooltips and several intermediate tooltips, some of which were not defined entirely, and used at least six different elements and one unspecified transition metal, and yet another unspecified "vitamin molecule" possibly requiring additional elements. Moreover, most reaction sequences were not completely specified and reaction closure was not 100%. It did not specify how the toolset may be constructed or what handle structures may have been required.

The Minimal Toolset paper proposes a 100% process closure which can be achieved using a minimal set of tools for mechanosynthesis, consisting of three primary tools: Hydrogen Abstraction (HAbst), Hydrogen Donation (HDon), and Dimer Placement (DimerP). These are assisted by six auxiliary tools, the discharged versions of Hydrogen Abstraction (AdamRad) and Hydrogen Donation (GeRad), and intermediate structures: Methylene (Meth), Germylmethylene (GM), and Germylene (Germ). And finally, a Hydrogen Transfer tool that is a compound form of the HAbst and GeRad tools.

Patterned Atomic Layer Epitaxy

Patterned Atomic Layer Epitaxy (PALE) consists of using a scanning tunneling microscope on a Hydrogen-terminated Silicon surface to remove individual Hydroge atoms. A variety of cases can be injected into the chamber, where they deposit on the depassivated area of the surface. Silylene (SiH2), in particular, will deposit and add a new layer to the crystal on the depassivated site.

Vertical growth is simple to achieve, but 3D, moving objects can be built using the same method: Grow a bed of Germanium, then grow the Silicon structures on top, and etch away the Ge to remove the structures and machines.

Books

General Audience

Engines of Creation: The Coming Era of Nanotechnology

Eric Drexler, 1986.

By the 'father' of nanotechnology, this book describes nanotechnology as a kind of radical biology, greatly extended in its capabilities, efficiency and the range of products it can produce, and most importantly, being computer-controlled. This brilliant work heralds the new age of nanotechnology, which will give us thorough and inexpensive control of the structure of matter. Drexler examines the enormous implications of these developments for medicine, the economy, and the environment, and makes astounding yet well-founded projections for the future.

Nanotechnology: Molecular Speculations on Global Abundance

Edited by BC Crandall, 1996.

The introductory chapter on molecular engineering, written by Crandall, covers an impressive range of ideas and facts and introduces some novel perspectives. He begins by explaining measurement systems and physical scales, and then introduces atoms and molecules, giving both scientific basics and historical perspective, and segueing into the most relevant facts from biochemistry and molecular biology.

Buy]

Technical

Nanosystems: Molecular Machinery, Manufacturing and Computation

Eric Drexler, 1992.

Stepping down from the radical vision of nanotechnology in Engines of Creation, Drexler began to formalize his ideas and detail them into something falsifiable. Along with Ralph Merkle, they designed molecular machinery and mechanochemical processes through which those machines could be built, basing their work on the application of the principles of mechanical engineering to the nanoscale (With considerations, of course) and mechanosynthesis, the synthesis of chemicals by mechanical constraints. The properties of diamond and diamond derivatives allow it to be a very useful and familiar building material in the otherwise largely unfamiliar environment of the very small.

Kinematic Self-Replicating Machines

Ralph Merkle, Robert Freitas, 2004.

With over 3,000 references, the book is an encyclopedic reference of all the work done on the field of physical, self-replicating machines, by Merkle and Freitas -- The latter is also the father of the Self-Replicating Lunar Factory.

This book offers a general review of the voluminous theoretical and experimental literature pertaining to physical self-replicating systems and self-replication. The principal focus here is on self-replicating machine systems. Most importantly, we are concerned with kinematic self-replicating machines: systems in which actual physical objects, not mere patterns of information, undertake their own replication. Following a brief burst of activity in the 1950s and 1980s, the field of kinematic replicating systems design received new interest in the 1990s with the emerging recognition of the feasibility of molecular nanotechnology. The field has experienced a renaissance of research activity since 1999 as researchers have come to recognize that replicating systems are simple enough to permit experimental laboratory demonstrations of working devices.

"THE standard reference in the field." - Mark Bedau, Editor, Artificial Life

Diamond Surfaces and Diamond Mechanosynthesis

Robert Freitas, Ralph Merkle, in preparation.

A full analysis of how to use programmable positional assembly to synthesize most arrangements of atoms permitted by physical law would be, at present, prohibitively complex. A more manageable project is to analyze a significant class of stiff hydrocarbons – in particular, diamond – that could potentially be synthesized by the use of a small set of positionally controlled mechanosynthetic tool tips. There is already widespread interest in the exceptional properties of diamond such as extreme hardness, high strength and stiffness, high thermal conductivity, low frictional coefficient, chemical inertness, and a wide bandgap. The molecular surface characteristics of diamond were extensively investigated both theoretically and experimentally in the 1990s, and many practical questions about the molecular structure of diamond surfaces have now been resolved. The fields of diamond CVD and adamantane chemistry provide additional understanding, both experimental and theoretical, of the myriad reaction mechanisms which can contribute to the growth of diamond.

Fundamentals of Nanomechanical Engineering

Robert Freitas, J. Storrs Hall, in preparation.

This course textbook, intended for use by 2nd or 3rd year college students in advanced engineering programs, will provide a solid grounding in the practical design of molecular scale machines composed of rigid covalent solids, with a strong emphasis on diamond and diamondoid materials. After an introduction to the unique aspects of nanoscale machinery and a review of the computational tools currently available to assist such designs, the mechanical characteristics of key materials and the fundamentals of load, stress, stiffness, and mechanical failure in nanoscale machinery will be explored in detail. This will be followed by discussions and examples of specific nanomechanical components and compound machines including bearings, fasteners, gears, linkages, drive mechanisms, motors and pumps, mechanical energy controllers, sensors, and programmable materials.

Nanotechnology: Research and Perspectives

Edited by BC Crandall and James Lewis, 1992.

This book contains the proceedings from the First Foresight Conference on Nanotechnology, held in October, 1989. The heavily illustrated volume of gives a good overview of the various fields contributing to molecular nanotechnology development. In addition to 18 chapters representing the talks and panel discussions from the conference, there are two appendices, which reprint "Machines of Inner Space", an article written by K. Eric Drexler for the 1990 Yearbook of Science and the Future, published by Encyclopedia Britannica, Inc, and "There's Plenty of Room at the Bottom: An Invitation to Enter a New Field of Physics", a prescient talk given by Richard Feynman in 1959 and published by California Institute of Technology in Engineering and Science magazine in 1960.

Prospects in Nanotechnology: Toward Molecular Manufacturing

Edited by Markus Krummenacker and James Lewis, 1995.

This book contains the proceedings from the First General Conference on Nanotechnology: Development, Applications, and Opportunities; held in November, 1992. It provides an accessible introduction to nanotechnology, and to applications and progress in related fields. There is also discussion of the funding situation, technology policy, and hypertext as a facilitating system for social problem solving and public debate.

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References

World Treasury of Physics, Astronomy, and Mathematics (Boston: Little, Brown
and Company, 1991), 22. First published in *Kenneth W. Ford, The World of
Elementary Particles* (Cambridge: Cambridge University Press, 1958).

[Link](http://en.wikipedia.org/wiki/Waldo_(short_story)#The_waldo).

1995.

Morita, “Mechanical vertical manipulation of selected single atoms
by soft nanoindentation using near contact atomic force microscopy,”
Phys. Rev. Lett. 90(2 May 2003):176102;
[abstract](http://prl.aps.org/abstract/PRL/v90/i17/e176102), [APS
story](http://physics.aps.org/story/v11/st19).