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[[Category:Technology]]
Nanotechnology is a broad range of technologies and
products whose characteristic dimensions are less than
about 1,000 nanometers. In short, nanotechnology is the
engineering of individual molecules and atoms.
How small is nano? A dime is 1,000 microns thick,
a human egg cell about 100 microns, a red blood cell
about 5 microns, a nerve axon about 1 micron, and a
virus about 0.1 micron, or 100 nanometers. DNA molecules
are less than 3 nanometers in diameter. Many common
proteins are only a few nanometers across. An atom
is about 0.1 nanometer.

==Nanofabrication==
This is the ultimate version of 3D printing (see
Minifacturing, p. 69). Atomic force microscopes
(AFMs) dip tiny probes with tips a few atoms wide into
wells of organic molecules (including carbon and
DNA). The probes can “engrave” or “write” on a
scale of a few nanometers.

Nanofabricators use robot-controlled
arrays of thousands or millions of parallel
probes to build components for larger microelectro-mechanical
systems, and to create complex nanostructures
consisting of a different type of molecules. These include
molecular computers, self-assembling “smart ink” used by
3D printers, and various types of nanomachines.

==Nanomachines==
Molecule-sized assembler robots, made of diamond,
that rearrange atoms to build just about anything are still
a holy grail, but smart pseudobiological nanomachines
exist. These devices are a fusion of microelectromechanics
and biomechanics. For example, light-harvesting
mechanisms derived from photosynthesis can create the
cellular fuel ATP (adenosine triphosphate), the same molecule
that powers our own cells. ATP powers various
types of nanomachines optimized for different activities.
A simple example is a rotor formed out of proteins and
metals nestled in a ring of ATPase proteins (an enzyme
used to assemble ATP-based nanomachines). These tiny
nanomotors perform various tasks, such as powering
tiny pharmaceutical factories that manufacture drugs
and pump them to tissues requiring them.

Tiny mobile nanobots perform cellular surgery or
protect the body against toxins, disease, and other conditions.
They recognize cells via their distinct antigens, much
the way the immune system does. Their tasks include cell
repair, waste product removal, toxin neutralization, and
chemical delivery. A patient is injected with a few cubic
centimeters of fluid containing millions of nanobots. Those
designed to travel the blood are small (2-3 microns), while
those intended to traverse tissue, or intestinal or air passages,
are several times larger. A typical device has a protein-
based frame and is propelled by bacteria-like cilia or
flagella. It possesses tiny rotors for molecular sorting and,
in some cases, miniature gas or chemical transport vessels.
Depending on its designed function, it will use these
nanoscale tools to scrub arteries clear of plaque, eradicate
cancers or perform on-site repairs to fix cellular damage, or
deliver chemical signals. Nanobots designed to operate in
the body are usually configured to a particular patient to
avoid triggering the body’s immune system. Other models
are either small or fast-acting enough to be ignored, or have
“stealth” coatings that can reconfigure their surface texture
to pass as the body’s native cells. Nanobots are mostly
powered by ATP metabolized from local oxygen and glucose,
and do not replicate.