Introduction to Nanotechnology: Looking At Nanoparticles
Scientists have been studying and working with
nanoparticles for centuries, but the effectiveness of their work has been
hampered by their inability to see the structure of nanoparticles. In recent
decades the development of microscopes capable of displaying particles as small
as atoms has allowed scientists to see what they are working with.
The following illustration titled “The Scale of
Things”, created by the U. S. Department of Energy, provides a comparison of
various objects to help you begin to envision exactly how small a nanometer is.
The chart starts with
objects that can be seen by the unaided eye, such as an ant, at the top of the
chart, and progresses to objects about a nanometer or less in size, such as the
ATP molecule used in humans to store energy from food.
Now that you have an idea of how small a scale nanotechnologists work
with, consider the challenge they face. Think about how difficult it is
for many of us to insert thread through the eye of a needle. Such an
image helps you imagine the problem scientists have working with
nanoparticles that can be as much as one millionth the size of the
thread. Only through the use of powerful microscopes can they hope to
‘see’ and manipulate these nano-sized particles.
Introduction to Nanotechnology Applications
The ability to see nano-sized materials has opened up a world of
possibilities in a variety of industries and scientific endeavors.
Because nanotechnology is essentially a set of techniques that allow
manipulation of properties at a very small scale, it can have many
applications, such as the ones listed below.
Drug delivery.
Today, most harmful side effects of treatments such as chemotherapy are
a result of drug delivery methods that don't pinpoint their intended
target cells accurately.
Researchers at Harvard and MIT have been able to attach special RNA
strands, measuring about 10 nm in diameter, to nanoparticles and fill
the nanoparticles with a chemotherapy drug. These RNA strands are
attracted to cancer cells. When the nanoparticle encounters a cancer
cell it adheres to it and releases the drug into the cancer cell. This
directed method of drug delivery has great potential for treating cancer
patients while producing less side harmful affects than those produced
by conventional chemotherapy.
Fabrics.
The properties of familiar materials are being changed by manufacturers
who are adding nano-sized components to conventional materials to
improve performance. For example, some clothing manufacturers are making
water and stain repellent clothing using
nano-sized whiskers in the fabric that cause water to bead up on the
surface.
Reactivity of
Materials.
The properties of many conventional materials change when formed as nano-sized
particles (nanoparticles). This is generally because nanoparticles have
a greater surface area per weight than larger particles; they are
therefore more reactive to some other molecules. For example studies
have show that
nanoparticles
of iron can be effective in the cleanup of chemicals in groundwater
because they react more efficiently to those chemicals than larger iron
particles.
Strength of Materials.
Nano-sized particles of carbon, (for example nanotubes and bucky balls)
are extremely strong. Nanotubes and bucky balls are composed of only
carbon and their strength comes from special characteristics of the
bonds between carbon atoms. One proposed application that illustrates
the strength of nanosized particles of carbon is the manufacture of
t-shirt weight
bullet proof
vests made out of carbon nanotubes.
Micro/Nano ElectroMechanical Systems.
The ability to create gears, mirrors, sensor elements, as well as
electronic circuitry in silicon surfaces allows the manufacture of
miniature sensors such as those used to
activate the airbags in your car. This technique is called MEMS
(Micro-ElectroMechanical Systems). The MEMS technique results in close
integration of the mechanical mechanism with the necessary electronic
circuit on a single silicon chip, similar to the method used to produce
computer chips. Using MEMS to produce a device reduces both the cost and
size of the product, compared to similar devices made with conventional
methods. MEMS is a stepping stone to NEMS or Nano-ElectroMechanical
Systems. NEMS products are being made by a few companies, and will take
over as the standard once manufacturers make the investment in the
equipment needed to produce nano-sized features.
Molecular Manufacturing.
If you're a Star Trek fan, you remember the replicator, a device that
could produce anything from a space age guitar to a cup of Earl Grey
tea. Your favorite character just programmed the replicator, and
whatever he or she wanted appeared. Researchers are working on
developing a method called molecular
manufacturing that may someday make the Star Trek replicator a
reality. The gadget these folks envision is called a molecular
fabricator; this device would use tiny manipulators to position atoms
and molecules to build an object as complex as a desktop computer.
Researchers believe that raw materials can be used to reproduce almost
any inanimate object using this method.
UNIT TEST OF NENO TECHNOLOGY
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