If this seems futuristic, keep in mind that intelligent machines are already making their way into our bloodstream.
There are dozens of projects under way to create bloodstream-based BioMEMS for a wide range of diagnostic and
therapeutic applications.
4
As mentioned, there are several major conferences devoted to these projects.
5
BioMEMS
devices are being designed to intelligently scout out pathogens and deliver medications in very precise ways.
For example, nanoengineered blood-borne devices that deliver hormones such as insulin have
been demonstrated
in animals.
6
Similar systems could precisely deliver dopamine to the brain for Parkinson's patients, provide blood-
clotting factors for patients with hemophilia, and deliver cancer drugs directly to tumor sites. One new design provides
up to twenty substance-containing reservoirs that can release their cargo at programmed times and locations in the
body.
7
Kensall Wise, a professor of electrical engineering at the University of Michigan, has developed a tiny neural
probe that can provide precise monitoring of the electrical activity of patients with neural diseases.
8
Future
designs are
also expected to deliver drugs to precise locations in the brain. Kazushi Ishiyama at Tohoku University in Japan has
developed micromachines that use microscopic spinning screws to deliver drugs to small cancer tumors.
9
A particularly innovative micromachine developed by Sandia National Laboratories has microteeth with a jaw that
opens and closes to trap individual cells and then implant them with substances such as DNA, proteins, or drugs.
10
Many approaches are being developed for micro- and nanoscale machines to go into the body and bloodstream.
Ultimately we will be able to determine the precise nutrients (including all the hundreds of phytochemicals)
necessary for the optimal health of each individual. These will be freely and inexpensively available, so we won't need
to bother with extracting nutrients from food at all.
Nutrients will be introduced directly into the bloodstream by special metabolic nanobots, while sensors in our
bloodstream and body, using wireless communication, will provide dynamic information on the nutrients needed at
each point in time. This technology should be reasonably mature by the late 2020s.
A key question in designing
such systems will be, How will nanobots be introduced into and removed from the
body? The technologies we have today, such as intravenous catheters, leave much to be desired. Unlike drugs and
nutritional supplements, however, nanobots have a measure of intelligence and can keep track of their own inventories
and intelligently slip in and out of our bodies in clever ways. One scenario is that we would wear a special nutrient
device in a belt or undershirt, which would be loaded with nutrient-bearing nanobots that could enter the body through
the skin or other body cavities.
At that stage
of technological development, we will be able to eat whatever we want, whatever gives us pleasure
and gastronomic fulfillment, exploring the culinary arts for their tastes, textures, and aromas while having an optimal
flow of nutrients to our bloodstream. One possibility to achieve this would be to have all the
food we eat pass through
a modified digestive tract that doesn't allow absorption into the bloodstream. But this would place a burden on our
colon and bowel functions, so a more refined approach would be to dispense with the conventional function of
elimination. We could accomplish that by using special elimination nanobots that act like tiny garbage compactors. As
the nutrient nanobots make their way into our bodies, the elimination nanobots go the other way. Such an innovation
would also enable us to out grow the need for the organs that filter the blood for impurities, such as the kidneys.
Ultimately we won't need to bother with special garments or explicit nutritional resources.
Just as computation
will be ubiquitous, the basic metabolic nanobot resources we need will be embedded throughout our environment. But
it will also be important to maintain ample reserves of all needed resources
inside
the body. Our version 1.0 bodies do
this to only a very limited extent—for example, storing a few minutes' worth of oxygen in our blood and a few days'
worth of caloric energy in glycogen and other reserves. Version 2.0 will provide substantially greater reserves,
enabling us to be separated from metabolic resources for greatly extended periods of time.
Of course, most of us won't do away with our old-fashioned digestive process when these technologies are first
introduced. After all, people didn't throw away their typewriters when the first generation of word processors was
introduced. However, these new technologies will in due course dominate. Few people today still use a typewriter, a
horse
and buggy, a wood-burning stove, or other displaced technologies (other than as deliberate experiences in
antiquity). The same phenomenon will happen with our reengineered bodies. Once we've worked out the inevitable
