Bootstrapping atomic precision
There actually is a way to place atoms to positional atomic precision
without achieving positional atomic precision in positional assembly.
- The level of precision in the product can be higher higher than
- the level of precision in the positional placement mechanism
by employing last stretch self centering of blocks.
(which basically is self-assembly with only one spot of attraction available)
The blocks need to come with an internal latent precision (sufficient stiffness) that is higher that the precision of the placement mechanism.
Assuming blocks that are notably bigger than single atoms:
For blocks which may be positionally-, or only topologically atomically precise,
in order to achieve sub-block sized precision in the placement mechanism
the critical parameter to meet is only lattice scaled stiffness.
Given larger pre-built blocks lower stiffness is tolerable.
Even deliberate usage of short tethers (as available in SDN) may be an option.
See semi-positional assembly on page: mechanosynthesis
More concretely that means:
Crude low stiffness assembly nano-mechanisms can in principle assemble
parts for next gen assembly robotics that is stiffer and thus capable of higher precision.
Eventually crossing the threshold from topological to positional atomic precision.
The ultimately achievable level of precision depends on the level of precision present in the placed blocks.
Concrete examples:
- semi-positionally pacing SPN with SDN mechanisms
=> in product: usually topological- perhaps very limited positional- atomic precision - positionally placing spiroligomers with an SPN tooltip
=> in product: usually positional atomic precision
Note though that
- placement mechanisms resolution must me high enough and
- stiffness must be low enough (yes you've read right)
such that
- there are no gaps in the mechanisms virtual placement lattice
Side-note: Also virtual placement lattice resolution of the placement mechanism must exceed resolution of the block-lattice in the product.
