Radical nanotechnology has taken a big step closer to the lab.
One kind of molecular manufacturing uses mechanosynthesis: transferring a few atoms at a time from a mechanically positioned "tool tip" to a growing workpiece. The idea is to build programmable shapes by doing a few reactions many times in programmable positions. This way, just a few reactions can be used to build an almost unlimited range of shapes.
Robert Freitas, the nanomedicine expert, has been working on how to build diamond using mechanosynthesis. He has previously posted a proposal to find a comprehensive set of diamond-building reactions that could be used to build arbitrary shapes; he thinks this may need as few as six to ten tool tips. And he thinks these tips can be found in as little as five years and $5 million.
The talk covers a lot of ground in detail. First, he overviews his previously published work (with collaborators at Zyvex) simulating a two-atom transfer from a tool tip to a diamond surface ("dimer deposition"). Then, he goes through four steps that could be used to build a diamond mechanosynthesis tool. The idea is to synthesize a tool tip molecule, deposit it on a surface to orient it, add a large "handle," and end up with a tool tip molecule attached to a nanopositioner, having a reactive dimer that will bond to a diamond surface when positioned correctly.
Step 1: Synthesis of Capped Tooltip Molecule
Step 2: Attach Tooltip Molecule to Deposition Surface in Preferred Orientation
Step 3: Attach Handle Structure to Tooltip Molecule
Step 4: Separate Finished Tool from Deposition Surface
He doesn't say a lot about step 1, other than that they're working on it and similar molecules have been synthesized as well as found in nature. Sounds to me like they're waiting till they write a patent.
He presents at least two alternate pathways for steps 2 and 3. One way to attach a multi-micron "handle" to the molecule is simply to use a CVD diamond-growing process; this has already been experimentally demonstrated on other molecules. Very clever! Step 4 should be accomplished simply by pulling.
Once the tip is free of the surface and held by the manipulator, it can be used to test dimer-deposition reactions.
This all looks doable today. It's only a fraction of the way to diamondoid molecular manufacturing. But it's a very important fraction. If it works, it will demonstrate once and for all that mechanically guided diamond-building vacuum chemistry is feasible. The recipe is detailed enough that it's already hard to argue it can't work. The claim that diamond-building can't be used to build machine parts seems likely to lose most of its remaining credibility.