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experimental and theoretical program to explore the feasibility of nanoscale
positional manufacturing techniques, starting with the positionally controlled
mechanosynthesis of diamondoid structures using simple molecular feedstock and
progressing to the ultimate goal of a desktop nanofactory appliance able to
manufacture macroscale quantities of molecularly precise product objects accord-
ing to digitally defined blueprints, is available at the Nanofactory Collaboration
website: http://www.MolecularAssembler.com/Nanofactory/Challenges.htm.
The purpose of this chapter is to examine the wide range of computational
tasks that might need to be performed by various representative classes of medical
nanorobots. Only a sampling of such tasks will be presented because time and
space do not permit an exhaustive survey. The discussion starts with descriptions
of several classes of medical nanorobots for which preliminary scaling studies have
already been published in the literature. Basic computational tasks are described
in each case. Following a more general discussion of the various major functions
common to many or all complex medical nanorobots, we introduce the concept of
nanorobot control protocols which are required to ensure that each nanorobot
fully completes its intended mission accurately, safely, and in a timely manner
according to plan.
15.2. EXEMPLAR MEDICAL NANOROBOT DESIGNS
Preliminary scaling studies of several classes of medical nanorobots have been
published in the literature and include respirocytes (artificial mechanical red cells)
[4], microbivores (artificial white cells) [5], clottocytes (artificial platelets) [6], and
chromallocytes (chromosome exchanging nanorobots) [7]. These studies are
summarized here, with emphasis on the computational tasks and requirements
for such devices.
15.2.1. Respirocytes
15.2.1.1. Nanorobot Description.
The first theoretical design study of a
medical nanorobot ever published in a peer-reviewed medical journal (in 1998)
described an artificial mechanical red blood cell or ''respirocyte'' [4] made of
18 billion precisely arranged atoms (Fig. 15.1)—a bloodborne, spherical 1-micron
diamondoid 1000-atmosphere pressure vessel [1e] with active pumping [1f]
powered by endogenous serum glucose [1g], able to deliver 236 times more oxygen
to the tissues per unit volume than natural red cells and to manage carbonic
acidity, controlled by gas concentration sensors [1h] and an onboard nanocom-
puter [1d, 12d].
In the exemplar design, onboard pressure tanks can hold up to three billion
oxygen (O
2
) and carbon dioxide (CO
2
) molecules. Molecular pumps are arranged
on the surface to load and unload gases from the pressurized tanks. Tens of
thousands of these individual pumps, called molecular sorting rotors [1f], cover a
large fraction of the hull surface of the respirocyte. Molecules of oxygen (O
2
)or
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