but complete digestion and excretion of the bugs remains can
take an hour or longer.
But the first thing a microbivore has to do is reliably acquire
a pathogen to be digested. If the correct bacterium bumps
into the nanorobot surface, reversible binding sites on the
microbivore hull can recognize and weakly bind to the bacte-
rium. A set of 9 different antigenic markers should be specific
enough, since all 9 must register a positive binding event to
confirm that a targeted microbe has been caught. There are
20,000 copies of these 9-marker receptor sets, distributed
in 275 disk-shaped regions across the microbivore surface.
Inside the receptor ring are more rotors to absorb glucose and
oxygen from the bloodstream for nanorobot power. At the
center of each receptor disk is a grapple silo; each disk is 150
nanometers in diameter.
Once a bacterium has been captured by the reversible
receptors, telescoping grapples rise up out of the microbivore
surface and attach to the trapped bacterium. The microbi-
vore grapples are modeled after a watertight manipulator arm
originally designed by Drexler  for nanoscale manufactur-
ing. This arm is about 100 nanometers long and has various
rotating and telescoping joints that allow it to change its posi-
tion, angle, and length. But the microbivore grapples need
a greater reach and range of motion, so they are longer and
more complex, with many additional joints. After rising out of
its silo, a grapple arm can execute complex twisting motions,
and adjacent grapple arms can physically reach each other,
allowing them to hand off bound objects as small as a virus
particle. Grapple handoff motions can transport a large rod-
shaped bacterium from its original capture site forward into
the mouth of the microbivore device. The bug is rotated into
the proper orientation as it approaches the open mouth.