Molecular Manufacturing Concepts

CRN Director of Research Chris Phoenix was asked by the U.S. National Academy of Sciences to prepare one-page briefing papers for each of their recent committee sessions investigating molecular manufacturing. Over the next several days, we will reprint those papers here.

The first is titled "Concepts of Molecular Manufacturing":

The fundamental concept of molecular manufacturing is the manufacture of precise molecular structures using reactions under direct mechanical control. There are several associated concepts and approaches that extend the utility of molecular manufacturing and/or are enhanced by it. Concepts related to nanoscale molecular manufacturing operations include nanoscale mechanical engineering, direct delivery of blueprints, and manufacture of manufacturing systems.

Self-assembly may play an important role in early molecular manufacturing. Feedstock molecules may self-assemble to the manufacturing tool tip. In some schemes, molecular building blocks may be joined into structures by a non-covalent process similar to self-assembly. In contrast to molecular manufacturing, the components in self-assembly must contain all the information required to make the final structure.

The theory of chemistry, especially computational chemistry, will be quite useful in developing synthetic reactions. Biochemistry and protein engineering may be useful in some approaches. However, synthetic chemistry uses self-assembly to bring molecules together, so it is less controlled than are mechanically guided reactions.

Mechanical engineering is not a requirement, but may be a useful approach for the design of mechanical operations to build predesigned structures—which may themselves be mechanical manufacturing systems. Direct delivery of blueprints—the ability to specify and control each detail of structure—will allow small intricate structures to be built more readily than bulk or imprecise technologies like chemistry and lithography. Nanoscale fabrication systems exist today (e.g. Seeman's DNA builder), and systems capable of building duplicate systems may be developed soon. (The digital nature of covalent reactions will retain precision in multi-generation copies.)

Taken together, these approaches promise to enable rapid exponential scaleup of manufacturing capacity. Unlike large tools, nanoscale tools may fabricate their own mass in minutes. The time to fabricate the tool's mass, relative throughput, decreases as the fourth power of the tool size. Though exponential manufacturing is not part of the definition of molecular manufacturing, it is an early consequence.

Beyond exponential manufacturing, molecular manufacturing recognizes the goal of combining many nanoscale manufacturing tools into integrated manufacturing systems ("nanofactories"), and combining their outputs into large integrated products. Preliminary nanofactory architectures indicate that the relative throughput for the entire system may be measured in mere hours. The ability to build kilogram-scale products with nanoscale features appears plausible.

Developing molecular manufacturing is a practical problem requiring a systems engineering approach. Although many details and capabilities remain to be worked out, molecular manufacturing is based on existing physical law and works toward a known goal. Development efforts can be divided into small research projects, producing advances across a range of disciplines.

NOTE: For a more detailed explanation, see "What Is Molecular Manufacturing?"

Comments

[Tom Craver]

A possible crude assembly technique based on electroplating:

If an atom-sharp needle were given a charge and brought close enough to a neutral-charge but conductive flat surface, it should draw a local induced charge to the surface below, sufficient to draw metal or other conductive material out of solution near the needle and deposit it on the surface below.

Keep the needle in place and a peak of material should build up beneath it. If the needle is close enough to the surface, the width of the peak should only be a few atoms wide - perhaps 1nm.

Moving the needle slowly away (and perhaps in a circular pattern around the peak) should build up a nm wide metal "pillar", as the only charged area on the growing pillar would be near the needle. Angle the needle in horizontally toward the top of a pillar to grow a horizontal bar.

Probably one would want to use many such needles closely spaced and operating in parallel, and build up layers of pattern about 1nm at a time.

It's not atom-precise, and it's certainly not diamond - but maybe it's something that could be done now (AFM, nanotube tips) to start making complex structures close to the scale that would be useful for bootstrapping MM.

awesome