Concluding our five-part series...
CRN's research is concentrated on what might be called the middle period of nanotechnology development, the point between today's nanoscale technologies and the fantastic possibilities of the further future (again, the recurring theme of CRN being in the middle).
In response to the negative associations of 'molecular nanotechnology' and 'MNT' with visionary universal assemblers, we made an attempt in the latter half of 2003 to distinguish this middle period as dealing with a limited version of molecular nanotechnology, or LMNT. This was characterized as implementing just a tiny fraction of possible chemistry, aimed at achieving a limited molecular manufacturing capability based only on carbon lattice configurations — diamond, graphite, and fullerenes — known collectively as diamondoid. We found, however, that although this is a useful and important distinction for technical writing, the meaning is too arcane and derivative for general usage.
Near the end of 2003, CRN decided to replace most usages of 'molecular nanotechnology' in our writing with 'molecular manufacturing'. This was thought wise not only to avoid the baggage associated with MNT but also to more specifically identify the period when large-scale manufacturing of products at the molecular level has become possible. To be more descriptive, we sometimes will use the fuller phrase exponential general-purpose molecular manufacturing. Exponential refers to the capability of the technology to reproduce its own means of manufacturing (self-copying). General-purpose suggests that the technology has application across a broad spectrum of industries and hence will affect many segments of society.
CRN Research Director Chris Phoenix has suggested a precise definition for molecular manufacturing as: "Any technology that implements digital operations, nanoscale construction, self-manufacture, programmable properties, and low error rates." Note that this definition could apply to any technology — diamondoid or not — that meets all five criteria.
Digital operations means that each manufacturing process has a well-defined discontinuity between success and error. If a certain design is constructed multiple times, the products that do not contain definite errors will be identical. This implies high reliability and predictability for the error-free copies.
Nanoscale construction means that the chemical building blocks can form, either singly or in combination, features in the 1-100 nanometer size range. Since no molecule is perfectly stiff, the physical arrangement of the features will not be perfectly precise. The permissible degree of uncertainty will depend on the application, but at least some physical coherence will be necessary for self-manufacture.
Self-manufacture means that the chemical system's range of designs must include devices that can contribute to the manufacture of other designs in the range. The functionality may range from flexible templating to nano-robotics doing pick-and-place operations. Self-manufacture may significantly lower the cost and increase the complexity of products, especially if it can be automated—which is made easier by digital operations and low error rates.
Programmable properties means that low-level designs can be specified or computed by describing higher-level features. Within a certain range, the design space will accommodate any specified feature without additional research. Essentially, this means that design rules and levels of abstraction can be used in the design process. A wide variety of features can be successfully specified without chemical research.
Low error rates means that the manufacturing process, and the subsequent operation of the products, has a usefully high success rate. Error rates may vary by many orders of magnitude. For example, a rate of 10-12 would be very poor for digital transistor logic, but a rate of 10-3 would be excellent for organic chemical synthesis. In general, an error rate per operation (e.g. per atom added to a product) of 10-9 to 10-12 may be adequate, though better rates may be achievable (Merkle 1997).
Although no technology today qualifies as molecular manufacturing, each of the specified requirements is implemented in some currently existing technology, and at least two nanotechnologies are developing rapidly toward a convergence of all five criteria. This definitional framework will serve in evaluating these and other new approaches that may be developed.
This five-part series has explained CRN's ongoing process of understanding and defining our work. By carefully and repeatedly examining our practices, we hope to succeed in walking the narrow middle line between dispassionate observation and zealous activism; between being boosters for nanotechnology and being sentinels. We aim to avoid being marginalized as irrelevant fanatics, and instead fulfill our chosen function as informed, principled, interested analysts and effective advocates for responsible use of advanced nanotechnology.
Mike Treder, CRN Executive Director