5.1.9.H

Kinematic Self-Replicating Machines

Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.

5.1.9.H Replicator Kinematics

H1. Process Manipulation Autonomy.

H2. Process Manipulation Redundancy. As with G2, replicator reliability is enhanced with greater redundancy of onboard manipulator systems.

H3. Process Manipulation Centralization.

H4. Number of Manipulator Types.

H5. Replicator Manipulation Degrees of Freedom.

H6. Assembly Mechanism Style. At an operating frequency of ~1 MHz, assembly of molecular-moiety building blocks onto a workpiece across 10-nm pathlengths dissipates ~0.001 pW using mill-type mechanisms and ~0.1 pW using manipulator-type mechanisms, though for 100-atom building blocks both device classes may dissipate ~0.001 pW per atom moved (Nanosystems [208], Sections 13.3.7.a and 13.4.1.f). Similarly, mill-type mechanisms appear to be at least an order of magnitude more productive per unit mass than manipulator-type mechanisms [208] – e.g., at ~1 MHz at 10-nm pathlengths, a typical 250,000-atom mill assembler could emplace ~10⁶ feedstock atoms/sec on a workpiece giving a productivity per unit mass (kg/sec per kg/assembler) of ~4 assemblers/sec, whereas a typical 5,000,000-atom manipulator assembler could emplace 5 x 10⁵ feedstock atoms/sec on a workpiece giving a productivity per unit mass of only ~0.1 assemblers/sec, a ratio of ~40:1 in relative productivity per unit mass. However, manipulator systems are far more versatile than mill systems (Section 5.9.6). This dimension may be generalized to describe, more broadly, programmable vs. hard-coded assembly actions.

H7. Positional Accuracy. The need for manipulator positional accuracy varies as a function of the building blocks being manipulated. High accuracy is required to manipulate small parts that require precise alignment, whereas only low accuracy may be required for large parts designed to tolerate greater imprecision during assembly. This dimension could be quantified either as a relative measure of positional accuracy as against parts dimensions, or else as an absolute measure of positional accuracy in nanometers, microns, millimeters, etc. For example, diamond mechanosynthesis on the C(110) diamond surface probably requires C₂ dimer positional placement accuracies on the order of 0.2-0.5 Å [2324, 2325]. See also E2, E8, E11, and F2.

Last updated on 1 August 2005