INGENIEUR
on the one hand the envisioned use of nano-
particles inside the body and the blood stream
(for diagnostic and therapeutic purposes), and
on the other hand – potential development of
new weapons of mass destruction enabled by
nanotechnology.
Current products of nanotechnology are much
more ordinary – reinforced plastics for the bicycle
frames, stain-resistant clothes, better cosmetics
and healthcare products, and tennis rackets
reinforced with carbon nanotubes.
An emerging field within nanotechnology is
known as bionanotechnology, which is a synthetic
technology based on the principles and chemical
pathways of living organisms. Bionanotechnology
looks for connections between molecular biology
and nanotechnology – guiding the development of
machinery at the nano-scale by the structure and
function of natural nano-machines found in living
cells.
As was the case with many new technologies,
solid predictions of their course of developments
are difficult to make. If nanotechnology were to
follow the paths of other new technologies (digital
communications, the Internet, etc.) the early
predictions – for the first ten years – would tend to
overestimate the impact of the technology (much
less is achieved compared with predictions).
However, the long-term prediction – for the first
50-75 years – would tend to underestimate that
impact (much more is achieved compared with
predictions).
Micro –Electro-Mechanical Systems
- MEMSnet
Micro-Electro-Mechanical Systems, or MEMS,
is a technology that in its most general form
can be defined as miniaturised mechanical and
electro-mechanical elements (i.e. devices and
structures) that are made using the techniques of
microfabrication. The critical physical dimensions
of MEMS devices can vary from well below one
micron on the lower end of the dimensional
spectrum, all the way up to several millimetres. The
types of MEMS devices can vary from relatively
simple structures having no moving elements, to
extremely complex electromechanical systems
with multiple moving elements under the control
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of integrated microelectronics. The one main
criterion of MEMS is that there are at least
some elements having some sort of mechanical
functionality whether or not these elements can
move. The term used to define MEMS varies in
different parts of the world. In the United States
they are predominantly called MEMS, while in
some other parts of the world they are called
“Microsystems Technology” or “micromachined
devices”.
While the functional elements of MEMS are
miniaturised structures, sensors, actuators, and
microelectronics, the most notable (and perhaps
most interesting) elements are the microsensors
and micro-actuators. Microsensors and micro-
actuators are appropriately categorised as
“transducers”, which are defined as devices that
convert energy from one form to another. In the
case of microsensors, the device typically converts
a measured mechanical signal into an electrical
signal.
More recently, the MEMS research and
development community has demonstrated a
number of micro-actuators including: microvalves
for control of gas and liquid flows; optical switches
and mirrors to redirect or modulate light beams;
independently controlled micromirror arrays
for displays, micro-resonators for a number of
different applications, micropumps to develop
positive fluid pressures, micro-flaps to modulate
airstreams on air foils, as well as many others.
Surprisingly, even though these micro-actuators
are extremely small, they frequently can cause
effects at the macroscale level; that is, these tiny
actuators can perform mechanical feats far larger
than their size would imply.
The real potential of MEMS would be fulfilled
when these miniaturised sensors, actuators, and
structures are merged onto a common silicon
substrate along with integrated circuits (i.e.,
microelectronics).
Although MEMS and Nanotechnology are
sometimes cited as separate and distinct
technologies, in reality the distinction between
the two is not so clear-cut. In fact, these two
technologies are highly dependent on one another.
The well-known scanning tunnelling-tip microscope
(STM) which is used to detect individual atoms
and molecules on the nanometre scale is a MEMS
device. Similarly, the atomic force microscope