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grapples until sensor readings reveal that passage through the slit has been
achieved, after which the grapples are retracted.
15.2.3. Clottocytes
15.2.3.1. Nanorobot Description.
Another theoretical design study de-
scribes an artificial mechanical platelet [6] or ''clottocyte'' that would allow
complete hemostasis in as little as
1 second, even in moderately large wounds.
This response time is on the order of 100-1000 times faster than the natural
hemostatic system. The baseline clottocyte is conceived as a serum oxyglucose-
powered spherical nanorobot
B
4 micron
3
volume)
containing a fiber mesh that is compactly folded onboard. Upon command from
its control computer, the device promptly unfurls its mesh packet in the immediate
vicinity of an injured blood vessel—following, say, a cut through the skin. Soluble
thin films coating certain parts of the mesh dissolve upon contact with plasma
water, revealing sticky sections (e.g., complementary to blood group antigens
unique to red cell surfaces [1ag]) in desired patterns. Blood cells are immediately
trapped in the overlapping artificial nettings released by multiple neighboring
activated clottocytes, and bleeding halts at once.
The required blood concentration n
bot
of clottocyte nanorobots required to
stop capillary flow at velocity v
cap
B
2 microns in diameter (
B
B
1mm/sec [1ah] in a response time t
stop
=1 sec,
assuming n
overlap
=2 fully overlapped nets each of area A
net
=0.1mm
2
,isn
bot
B
n
overlap
/(A
net
t
stop
v
cap
)=20mm
3
, or just
110 million clottocytes in the entire
5.4-liter human body blood volume possessing
B
11 m
2
of total deployable mesh
B
0.4mm
3
of clottocytes, which produces a negligible
serum nanocrit [1ai] or ''Nct'' of
surface. This total dose is
B
0.00001% (nanorobot/blood volume ratio).
During the 1 second hemostasis time, an incision wound measuring 1 cm long and
3mm deep would lose only
B
6mm
3
of blood, less than one-tenth of a single
droplet. There are 2-3 red cells per deployed 1 micron
2
mesh square, more than
enough to ensure that the meshwork will be completely filled, allowing complete
blockage of a breach.
Total natural bleeding time, as experimentally measured from initial time
of injury to cessation of blood flow, may range from 2-5 minutes [53] up to
9-10 minutes [54, 55] if even small doses of anticoagulant aspirin are present [56],
with 2-8 minutes being typical
B
1 sec response
time, artificial mechanical platelets appear to permit the halting of bleeding
100-1000 times faster than natural hemostasis. While 1-300 platelets might be
broken and still be insufficient to initiate a self-perpetuating clotting cascade, even
a single clottocyte, upon reliably detecting a blood vessel break, can rapidly
communicate this fact to its neighboring devices, immediately triggering a
progressive controlled mesh-release cascade. Clottocytes may perform a clotting
function that is equivalent in its essentials to that performed by biological
platelets—but at only
in clinical practice. With a
B
0.01% of the bloodstream concentration of those cells.
Hence clottocytes appear to be
B
10,000 times more effective as clotting agents
than an equal volume of natural platelets.
B
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