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September 15, 2009
Introduction toNanotechnology
Meyya Meyyappan
Developed exclusively for IEEE Expert Now
Sponsored by: IEEE Educational Activities
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Course Presenter’s Biography
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Meyya Meyyappan is Chief Scientist for Exploration Technology at the Center for
Nanotechnology, NASA Ames Research Center in Moffett Field, CA. Until June 2006, he
served as the Director of the Center for Nanotechnology as well as Senior Scientist. He is a
founding member of the Interagency Working Group on Nanotechnology (IWGN) established
by the Office of Science and Technology Policy (OSTP). The IWGN is responsible for putting
together the National Nanotechnology Initiative.
Dr. Meyyappan has authored or co-authored over 175 articles in peer reviewed journals and
made over 200 Invited/Keynote/Plenary Talks in nanotechnology subjects across the world.
His research interests include carbon nanotubes and various inorganic nanowires, their
growth and characterization, and application development in chemical and biosensors,
instrumentation, electronics and optoelectronics.
Dr. Meyyappan is a Fellow of the Institute of Electrical and Electronics Engineers (IEEE), the
Electrochemical Society (ECS), AVS, and the California Council of Science and Technology.
In addition, he is a member of the American Society of Mechanical Engineers (ASME),
Materials Research Society, and American Institute of Chemical Engineers. He is the IEEE
Nanotechnology Council Distinguished Lecturer on Nanotechnology, IEEE Electron Devices
Society Distinguished Lecturer, and ASME's Distinguished Lecturer on Nanotechnology
(2004-2006). He served as the President of the IEEE's Nanotechnology Council in 2006-
2007.
For his contributions and leadership in nanotechnology, he has received numerous awards
including: a Presidential Meritorious Award; NASA's Outstanding Leadership Medal; Arthur
Flemming Award given by the Arthur Flemming Foundation and the George WashingtonUniversity; 2008 IEEE Judith Resnick Award; IEEE-USA Harry Diamond Award; AIChE
Nanoscale Science and Engineering Forum Award. He was inducted into the Silicon
Valley Engineering Council Hall of Fame in 2008 for his sustained contributions to
nanotechnology. For his educational contributions, he has received: Outstanding
Recognition Award from the NASA Office of Education; the Engineer of the Year Award
(2004) by the San Francisco Section of the American Institute of Aeronautics and
Astronautics (AIAA); IEEE-EDS Education Award.
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Course Outline
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This course is designed to give a brief introduction to nanotechnology. This course begins byintroducing the subject of nanotechnology to the beginner including a definition of
nanotechnology, different nanomaterials, what is special about nano, why are nanoproperties
different from bulk properties and several examples, and the impact of nano on each
economic sector with examples.
After completing this course you should be able to develop an understanding of:
The definition of nanotechnology which comes from the US National Nanotechnology
Initiative.
How nanoscale properties are different from bulk material properties and what the
reasons are for this change in properties.
Near term and long term opportunities.
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Course Summary / Key Points
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Course Summary / Key Points
Defined nanotechnology
Examined why and how properties are different
Discussed the impact of nanotechnology in various sectors
Provided a clear assessment of opportunities
Related IEEE Expert Now Titles Include:
Nanotechnology 101 Part 1 by H.-S. Philip Wong
Nanotechnology 101 Part 2 by H.-S. Philip Wong
Nanomaterials and their Applications by Meyya Meyyappan
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Course Transcript
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Outline
This lecture is designed to give a brief introduction to nanotechnology. There are four topics
which will be covered in this lecture. First I will provide a definition of nanotechnology. For
this I will use the definition that came from the US National Nanotechnology Initiative.
Then I will discuss how nanoscale properties are different from bulk material properties and
what the reasons are for this change in properties.
Every application picks out a material based on a particular property. If most of the
properties are going to change at the nanoscale, then you can expect an impact on variousapplications across all sectors. This will be discussed.
And then finally, I will provide an assessment of near term and long term opportunities.
What is Nanotechnology?
A nanometer is a billionth of a meter. To put this in context, a hydrogen atom is .04
nanometer. You would need to arrange ten hydrogen atoms end-to-end in a row to cover
one nanometer.
Proteins are about one to 20 nanometers. The critical dimensions of the source during
separation in a silicone CMOS in 2007 was 60 nanometers. The diameter of a human hair is
approximately ten microns.
So nanotechnology deals with the creation of useful or functional materials, devices and
systems of any useful size through control and manipulation of matter on the nanometer
length scale.
So I need to provide a few clarifications. First, what we mean by nanoscale here is one to
100 nanometer and, at least, in one principle in direction.
Second, the device or system or the final object we are trying to make that can be of any
size. Now remember, nanoscale is not a human scale. So a useful object can be of any
size. The key is to assemble that final object from nanoscale materials.
And the next clarification I want to provide is that I deliberately highlighted several items on
this screen. The reason I did that was to distinguish what serious scientists and engineers
are doing across the world as defined by the US National Nanotechnology Initiative, as well
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as similar national initiatives in other countries to distinguish this from science fiction typenanobars and other fantasies.
So now, moving beyond the length scale, the nanometer length scale requirement that I just
talked about is just a necessary condition but not a sufficient condition.
The more important condition or the sufficient condition is to take advantage of the change in
properties that happen just because we are going to the nanoscale.
So if you ask, do properties change at nanoscale? Absolutely. Physical, chemical, electrical,
mechanical, optical, magnetic and all these properties change when you go from bulk scale
to nanoscale. So nanotechnology is about taking advantage of these novel properties and
doing something useful with it.
What is Special about Nanoscale?
A natural question would be what is special about nanoscale? All matter is made up of atoms
and molecules. And they are less than a nanometer. And that is what we study in chemistry.
Then you take solids, they consist of an infinite array of atoms bound to each other and that
is what we study in condensed matter physics.
There is an in between meso-world and that is what nanoscience deals with. In the
nanoscale, things are so small that you cannot apply classical laws of physics. For example,
like Ohms law.
Once you reach nanoscale, properties also become size dependent. I will talk about that in a
few minutes.
For nano materials, the surface to volume ratio is very high. To understand this, let’s just
take a cube. We know the surface area is six times A squared, where A is the dimension of
the cube and then the volume is A cubed.
Now cut this cube into two halves. You add two more exposed areas, adding to the surface
area. But the volume remains the same. Now you keep on repeating this a billion times.
Then you understand what I am talking about in terms of increased surface area for
nanoscale materials.
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What is new about Nanoscience?
When the US national nanotechnology initiative was started in 2000, it was common to hear a
few people saying, oh I have been doing nanotechnology for X number of years, where X is
an attractively large number in someone’s career.
The truth is, yes, a lot of things we know work by the same principles of nanoscience. For
example, photography and catalysis were developed empirically decades ago.
You can think of many, many examples like that. In some of these examples, the role of
nanoscale phenomena was not understood until recently.
Powerful techniques to visualize things at the atomic scale, like the atomic force microscope
and scanning tunneling microscope came into the labs only within the last two decades.
Once you can see materials at the nanoscale and you can characterize them, then you gain
some understanding. With understanding come opportunities to improve things further. Also
getting a handle on material properties and their relation to the structure, that can perhaps
help to design complex systems. Think of a design and material with desirable properties.
Some 'Nano' Definitions
Next I want to provide some nano definitions. The first one is a cluster. A cluster is a
collection of units and a unit could be an atom or a reactive molecule. So a cluster is a
collection of units of up to about 50 units. A colloid is a stable liquid phase which contains
particles in the one to thousand nanometer range. So a colloid particle is one such, one to
thousand nanometer particle.
A nanoparticle can be a solid particle with the dimensions in the one 200 nanometer range
and the particle could be non-crystalline or a single crystalline manmade material or an
aggregate of crystallites.
And finally, a nano crystal is a solid particle which is a single crystal and it is also in the
nanometer range. So these are just a few definitions.
Percentage of Surface Atoms
Earlier we discussed the large surface to volume ratio for nanoscale materials. We can also
look at the same thing from the atomic arrangement for nanoscale materials.
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An atom in the bulk is surrounded by neighboring atoms and all its bonds is satisfied bysharing with the neighbor atoms.
On the other hand, the surface atoms do not have neighbors on the exposed side and so
they are left with unsatisfied bonds. That is why surface atoms are more reactive. Now the
smaller the size, there will be more surface atoms.
Let us look at close packed, full shell clusters. For a large shell cluster, only a small
percentage of the atoms are on the surface. For example, the seven shell cluster, it has only
about 35% of the atoms on the surface. The total number of atoms are 1,415. Out of these
35% of the atoms are on the surface.
But when you get down to a single shell cluster, a whopping 92% of the atoms are on the
surface. There are only a total number of atoms at 13 but 92% of the atoms are on the
surface.
The plot shown here gives similar information, differently as a function of particle size. This
particular data is specific to iron particles.
When the particle size is about 30 nanometers, the surface atoms constitute only about five
percent. But when you go down to one to two nanometer particle size, now we are looking at
90% of the atoms on the surface.
Size Dependence of Properties
In materials where chemical bonding is strong the valence electrons delocalize extensively.
How much this happens can depend on the size. Of course, a structure also changes with
size. These two things together can lead to change in physical and chemical properties,
which will depend on size. Some examples include optical properties, bandgap, melting point,
specific heat. I will talk about some of these things in detail in a few moments.
If you are wondering, when we put all these nanoparticles together—when we consolidate
them into a macroscale solid--would the properties still change? Yes, in some cases new
properties are still possible. One example is enhanced plasticity.
Size-Dependent Properties: Examples
Next we’ll discuss the size dependence of various properties. I will begin with bandgap.
For some interconnecting materials, such as silicone, cadmium sulfide and zinc oxide, the
bandgap changes with size. First, what is bandgap? It is the energy needed to promote an
electron from the valence band to the conduction band.
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For silicone, the bandgap is 1.1 EV. When you mix silicone as a three nanometer nanowire,
then the bandgap becomes pretty high--pretty close to three electron volts.
Interestingly, when the bandgap lies in the visible spectrum, then when the bandgap changes
with size, it also means that the color will change.
Next I will talk about magnetic field. The strength of a particles internal magnetic field is size
dependent. For magnetic materials such as nickel, cobalt, and iron, that is true.
The magnetic memory is the force needed to reverse that internal magnetic field I just
mentioned. So if the strength of the internal magnetic field is going to be size dependent,
then the course, the force, the magnetic memory is also in response going to be size
dependent.
Color
For small particles, color becomes size dependent. Light is partially absorbed by electrons in
matter. The complimentary part of the light is visible as color. Perfectly smooth, polished
metal surfaces essentially reflect all the light thanks to their high density of electrons. So in
those cases we see no color but just a mirror like surface.
On the other hand, tiny particles absorb light which leads to some color. Then there
becomes size dependent. For example, gold, it readily forms nanoparticles. It doesn’t get
very easily oxidized. It exhibits different colors depending on the particle size.
Interestingly, thousands of years ago, the Chinese pottery makers used gold colloids to add
color to the pottery they were making. The ruby glass that they made, contain very finely
dispersed gold particles.
Likewise, silver and copper also, in small scale particles give out very attractive colors.
Specific Heat
The next property we’ll address is specific heat. What is specific heat?
If you take a very small sample of mass M, specific heat is the amount of heat delta Q
required to raise the temperature of that mass by a small delta T. The common unit that we
use is joules per kilogram degree Kelvin, are accurately calories per gram degree Kelvin.
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By the way, one calorie is the heat needed to raise the temperature of one gram of water justby one degree.
Specific Heat (cont.)
In the case of many nanocrystalline materials, experimental measurements have been made
for establishing the values of a specific heat as a function of size.
One example is palladium nanocrystalline particles. For a six nanometer particle, the specific
heat is close to 50 percent higher compared to the bulk value. Likewise, for copper, for an
eight nanometer particle, it is close to about eight percent higher compared to the bulk value.
So uniformly in all these cases, the specific heat of nanocrystalline materials is higher
compared to the bulk property.
Melting Point
For metals, semiconductors and other materials, the melting point is also size dependent in
the nanoscale. For example, gold melts at 1,064 degrees centigrade. But nanoparticles of
gold melt much sooner or quicker. This plot shows melting point of gold particles as a
function of particle radius.
If you look at something such as a five nanometer particle, it melts approximately a couple
hundred degrees quicker or sooner than bulk gold.
Melting Point Dependence on Particle Size: Analytical Derivation
It is possible to derive an analytical expression for the deviation in melting point from the bulk
value T naught. That deviation is delta theta which is shown in the expression here.
So here, this deviation of melting point from the bulk value, which is delta theta, has an
inverse dependence on particle radius that is a one over R dependence--that is the important
point.
The other parameters here are L, which is a latent heat of fusion; rho which is a particle
density and sigma which is a surface extension co-efficient for a liquid/solid interface.
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Melting Point Dependence on Particle Size
From the analytical expression we saw previously, a couple of things are clear. The first is
that a lowering of the melting point is proportional to one over particle size. The second is
that the deviation in melting point, delta theta, can be as large as a couple of hundred
degrees when the particle size gets below ten nanometer.
One important point is how this applies to isolated particles. That is how the measurements
were made and even the analytical expression was derived for isolated particles. On the
other hand, if these nanoparticles are embedded in a matrix, then the melting point
dependence could be higher, or it could be lower. The melting point deviation from the bulk
melting poin may be lower or higher. All of those things are going to depend on the strength
of the interaction between the particle and the surrounding matrix.
Electrical Conductivity
Next we’ll discuss electrical conductivity. Take metals for example. Their conductivity is
based on their advanced structured. If the conduction band is only partially occupied by
electrons, then the electrons can move in all directions without getting scattered. As long as
the crystal lattice is perfect.
The electron mobility is given by this formula shown here. The electron mobility is
proportionate to lambda, where lambda is a mean free path between collisions. The electron
mobility is inversely proportional to the mass. The smaller the mass, the higher the mobility
is.
Other parameters here include V which is the electron speed and epsilon naught, which is the
dielectric constant in vacuum.
Electrical Conductivity (cont.)
So far, what we have been discussing is for an ideal case where electrons do not get
scattered and the crystal lattice is perfect. But in reality, the electrons always get scatteredby the defects in the semiconductor.
For example, these defects include vacancies and foreign atoms and dislocations, et cetera.
In a bulk metal, the collective motion of electrons is described by Ohm’s law. But on the
other hand, when particles become small, the band structure begins to change. So now the
band structure consists of discreet levels and the Ohm’s law is no longer going to be valid.
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I-V of a Single Nanoparticle
Suppose we have a single nanoparticle. What does the I-V characteristics of this single
nanoparticle look like? Ohm’s law is not going to be valid, as I noted. By the way, Ohm’s
law represents a linear current voltage relationship.In this case, Ohm’s law is not going to
hold. So what is the law that holds for a single nanoparticle?
First, how do you even measure current voltage relationships for such a small system? After
all, you cannot directly contact the particle because the contact characteristics may very well
over run the transport through the particle.
So what we do is to first, cushion the particle on either side with a capacitance. And then we
use a pair of electrodes on either side. So the current voltage relationship measured this way
is what is shown here. And for a single quantum dot particle, it is not linear; instead it is
rather like a staircase.
First there is no current at all until we reach a threshold voltage given by plus or minus E over
2C, where C is the particle capacitance and E is the electronic charge. This is called the
Coulomb blockade.
Once you reach this value, then one electron is transferred. The equivalent current now is E
over RC, where R is the channeling resistance.
So now with every additional or incremental voltage of the size, E over 2C, when we add that
to the particle, then the current will go up by E over RC. So that is why this staircase like
behavior is seen for a single nanoparticle.
I-V of a Single Nanoparticle
This screen describes in a written form what we have just discussed.
Impact of Nanotechnology
So far we have talked about various properties that change when you go from bulk scale to
nanoscale. So the logical question is, so what? Every application starts with the material
selection. And we make this choice because that material happens to provide the very
property that we are looking for.
Now if most or all properties are going to change because of going to the nanoscale, then
you can imagine pretty much all applications will have an impact from nanotechnology. So
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that impact is expected to be on pretty much everything: electronics, computing,communications, materials, manufacturing, health, medicine, energy, environment,
transportation, national security, so on and so forth.
So then nanotechnology is not any single technology. In fact, we must use the plural
nanotechnologies. But it is better to use the singular nanotechnology but rather think of it as
an enabling technology. In other words, nanotechnology is not the end in itself, it is just a
means.
Expected Nanotechnology Benefits in Electronics and Computing
Next we’re going to talk about the expected impact of nanotechnology on electronics andcomputing. On the logic side, the possibility is processes which require much lower energy
while maintaining performance improvements that we have been used to so far.
One of the biggest problems today is power dissipation. Look at the graphic shown here,
which came from Intel. This plots power dissipation in watts per centimeter square through
various generations of Intel chips. They have also plotted a few things, like, a hot plate and a
nuclear reactor, rocket nozzle and eventually the surface. So if you look somewhere around
2010 or in the vicinity, the power dissipation is expected to be pretty close to one kilowatt per
centimeter squared, which is comparable to the nuclear reactor or rocket nozzle.
So that gives you an idea what kind of problems that we are anticipating when it comes to
power dissipation while continuing to enjoy the levels of performance improvement.
So what nanotechnology is hoping to do is to continue to give us this performance
improvement but at the same time reducing this energy consumption, and also, providing
better solutions for heat dissipation.
On the memory side, multi-terabyte levels of storage is what nanotechnology is hoping to
provide. And beyond these, there is also the concept of more and more, which means more
than what Morse law has been giving us so far, just increased performance. This idea talks
about integrating logic and memory without a functional component.
Say for example, the integration of logic, memory and sensors. You can say the impetus is
the inspiration for this comes from our own head where we combine the ability to do logic and
memory, along with a few sensors. Also, there are currently efforts to double up intelligent
appliances by integrating the advances in IT network and communications, along with new
sensors. Here the bottleneck is the sensor. The sensor has to be very small. It has to be
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relayable and more importantly, there has got to be very low power consuming. So this is anarea where nanotechnology can help.
Health and Medicine
In the area of health and medicine, it is well known that the human genome has been
successfully sequenced. But we have not seen the pervasive impact of this yet.
One of the current research efforts involves speeding up this gene sequencing, say within a
couple of hours. One approach involves using a tiny nanopore, maybe one or two nanometer
in diameter in a membrane. This membrane is inside a cell containing DNA in a buffer
solution. Under an applied electric field the DNA will migrate. When it goes through the pore,the DNA will block and suppress the background current, which is already there because of
the ionic movement within the electrolyte.
What people are trying to do is to correlate the reduction in current, and determine how long
the reduction lasts until the DNA gets out of the pore. So trying to correlate these two things,
the reduction in current and how long this translocation happens—correlating these two thing
to the individual nucleotypes. When this effort is successful, it is possible that the
intergenetic makeup of someone can be sequenced with a couple of hours. This then would
lead to the possibility of individualized medicine. Currently, diagnostics and therapeutics are
based on statistics. In the future, these can be based on one’s own genetic makeup.
Other applications for nanotechnology in health and medicine efforts include effective and
targeted drug delivery. Also, the use of nano materials and composites to double up rejection
proof, more durable artificial body parts, such as organs and tissues, muscles, bones, et
cetera. And finally, early warning sensors for diagnostics of infectious diseases and other
illnesses--this is an area that is receiving a lot of attention from the nano/bio community.
Materials and Manufacturing
Next let’s look at the f ield of materials and manufacturing. Until now if you want to reach a
net shape of a given material, we start with a bulk sample and then machine it until we get achip.
In the future, we are hoping to reach the same net shape by starting from bottom up and
assembling it. Hopefully, when we are successful in doing that, it should help us to produce
lighter, stronger materials with programmable properties, possibly reducing failure rates and
thus reducing life cycle costs.
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There is also a lot of work going on, on bio inspired materials for which the original concept isfrom nature and all we are trying to do is to mimic it. For example, self-cleaning glass
modeled after the lotus leaves, which are always clean from dirt and other things. There has
been work on developing this synthetic coating using polymeric materials or carbon
nanotubes.
Another area of active research is multi-functional materials. As the name implies, it is more
than one function. But the basic function is always load-bearing. That is to support a load.
And then on top of that load bearing structure, you can add additional functions. For example,
terminally insulating or terminally conducting, electrically insulating or electrically conducting,
sensing physical chemical variables, physical variables, such as stress, strain, pressure, and
chemical variables as contamination.
So that idea is called multi-functional material development.
Finally, self healing materials is also an area of interest. Here the inspiration, again, comes
from nature.
For example, if you get a paper cut, it heals by itself. So the idea here is to develop a
material or a composite where when some fracture or some breakdown occurs, right away it
gets healed before you apply more and more stress on that material, making the breakage
larger and larger and then eventually leading to catastrophic failure. So healing it right away.
So that concept is called self healing.
At this point, the preliminary idea of self healing has been demonstrated in a simple polymer
composite.
Energy Production and Utilization
On the energy production and storage side, nanomaterials are being investigated to improve
the efficiency of solar power cells, fuel cells, super capacitors, batteries, et cetera.
On the energy utilization side, the biggest effort is on solid state lighting. If every home and
industry in the United States replaces conventional bulbs with solid state lighting, we can cut
then annual electricity consumption of the nation by about ten percent. But at this point, solidstate lighting costs are very high. Nanomaterials and processes are being investigated to
increase the efficiency and reduce the cost.
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Benefits of Nano in the Environment Sector
I mentioned previously that nanomaterials have a very large surface area for a given volume.
For example, if you take single wall carbon nanotubes, they have approximately a surface
area of 1600 square meters per gram.
What that means is it only takes four grams of carbon nanotubes to cover an area equivalent
to the size of an American football field. So what does large surface area mean for large
absorption rates for various gases and vapors?
This large absorption possibility leads to applications using nanomaterials for separating
pollutants, to be able to support catalysts for conversion reactions, such as converting nasty
gases, like, nitric oxide to benign gases, like, nitrogen and oxygen.
Other applications include waste remediation, developing fi lters and membranes for water
filtration. And also to convert sea water to drinking water known as desalination.
Another area, this is particularly, the catalytic converters that we use in automobiles, they use
expensive platinum. That platinum is the material of choice because of its efficiency in the
catalytic converters.
Currently, there are efforts going on that use nanoparticles of other materials just to replace
the expensive platinum. So this will reduce the auto emission while using much less
expensive materials. This area is called rational design of catalyst.
Benefits of Nanotechnology in Transportation
Next we’ll discuss nanotechnology applications in the transportation sector. I previously
mentioned the catalytic converter, and in addition, terminal barrier and wear resistant
coatings are also examples. There is also lightning protection for aircraft now that more and
more percentage of the aircraft is no longer metal, but composite--high strength, lightweight
composites for increased fuel efficiency. Also if you succeed in developing electric vehiclesin the near future, then we will need a whole host of new sensors under the hood.
National Security
In national security information takes a central role. Gathering information and transmitting
information--only to the people who need to know-- and also protecting the information from
getting into the wrong hands is key. For these reasons, the Department of Defense is the
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sponsor of nanoresearch activities in electronics, fortonics, communications and all otherrelated fields. Another key area for the military is developing reliable sensors for chemical, bio
and nuclear threats.
One of the major costs for the Army is from the logistics and fuel needs of tanks, which weigh
about 80 tons, especially when you have to transport 1,000 of them 8,000 miles away from
home. If the weight of each of these tanks can be reduced, let’s say by at least about 20 to 30
percent, through the use of better composites, compact instruments, compact sensors and
reducing the weight of all the gear, then the savings will be enormous.
The same idea applies to the soldier backpack as well, which currently weighs about 70
pounds. So in both cases, the philosophy is increase functionality per unit weight.
Assessment of Opportunities
So far we have talked about the possible impact of nanotechnology on various economic
sectors. Next I just want to talk about what is likely to happen in the near term, medium term
and long term.
So when we talk about near term, there are a lot of things that are already happening. For
example, the automotive industry is currently using nanoparticles in body moldings, timing
belts and engine covers.
Multi-wall nanotubes are being added to the fender making process. You add a very small
quantity of multi-wall nanotubes which will make the fender electrically conductive. So this
would allow an easy painting job of the fenders in big batches, in large electrochemical vats,
just as a way the metal fenders used to be painted in the old days.
Low-tech fields such as cosmetics and sporting goods, they have been active in using
nanomaterials. In fact some of the products that are available are shown here in the image.
Catalysts using nanoparticles is an area which is an extension of an existing market. So
these are all some of the near term activities which are already happening.
Assessment of Opportunities (Cont.)
In the medium term, which is five to ten years, the possibilities include higher density memory
devices, biosensors, biomedical advances, improved solid state lighting. So these are all
some applications we might see in the medium term.
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When we talk about long term, which is 15 years and beyond, we may see nanoelectronicsdevelopments beyond the silicone CMOS and nanocomposites in aerospace and automotive
industries. But this will take a long time because aerospace and automotive industries are
risk averse industries. Overall when we talk about long term, many of the applications may
very well be things that we have not even thought about yet.
This reminds me of something that I read about, Prof. Herbert Kroemer, a Nobel Laureate
from the University of California, Santa Barbara. In the early days of his career, in the 1950s
and 60s, in both the labs and then at UC Santa Barbara, he was focused on hydrojunction
theory in three/five compounds, and related topics. Those were the days of rapid silicone
technology development, along with the integrated circuit. So it was not uncommon for
colleagues to wonder at that time, what was all this hydrojunction stuff that he was working
on, what was it good for?
Interestingly, in the 50s and 60s, who would have guessed at that time applications for these
hydrojunction theory would include things like the lasers in supermarkets, supermarket
scanners to everything else, such as the CDs and DVDs and then hydrojunction devices in
mobile phones. So when it comes to real long term, realistically things are very hard to
predict.
Revolutionary Technology Waves
I previously mentioned on that nanotechnology is an enabling technology. In history, there
have been other enabling technologies. Some examples include railroad and automobiles.
Technologically, take the matter of the steam engine and internal combustion engine. From
their impact point of view, they are far more that. They brought people together. They
promoted commerce. Likewise, computers also have revolutionized the way we do things
and pretty much everything. So an analysis of these enabling technologies, it shows a
common theme. These enabling technologies first take about 25 years or so to put some
roots. Then for the next 50 to 60 years, there is a steady increase on the economical impact.
From the nanotechnology point of view, we are in the very, very early stages, essentially in
the exploratory mode.
Environment, Safety and Health Concerns
Finally I want to finish up with a very brief discussion on the environment safety and health
concerns.
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Course Transcript
IEEE Expert Now Introduction to Nanotechnology Transcript pg. 19 / 21
There are real concerns out there about the impact of nanomaterials on the environment,safety and health. These concerns arise because the size is much, much smaller than we
have ever known. More importantly, the properties are very different from the bulk
counterparts, which we have been using.
What is not known at this point is, at least for most of the materials, what is the effect of these
materials on skin if you come in contact? What is the effect on lungs if you inhale any of
these accidentally? What would be the environmental impact that includes air, water and
landfills? What are the worker and public safety issues?
So these things are not well known at this point. Well, our knowledge is power. We need to
put resources and develop all the knowledge. We need to have a comprehensive database.
This knowledge then will tell us if we need a new set of regulations beyond what we have
now. Because we simply cannot make rules and regulations based on speculations.
Hopefully, what I have talked about so far should give you some introduction to
nanotechnology. What nanotechnology is. Why nanomaterials are different from their bulk
counterparts, their bulk cousins.
What is the impact of nanotechnology on various economic sectors? And then finally, what is
it that we can expect in the market in the near term, medium term and long term?
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Glossary
IEEE Expert Now Introduction to Nanotechnology Transcript pg. 20 / 21
Nanometer
1 nanometer (nm) is one-billionth of a meter.
Nanoscale
Characterized by typically 1-100 nanometers at least in one of the principal directions,
according to the U.S. National Nanotechnology Initiative.
Nanoparticle
A solid particle in the 1-100 nanometer range that can be noncrystalline, single crystalline or
aggregate of crystallites.
Carbon nanotube
Tubular form of carbon with diameter as small as 0.4 nm and above, and a large aspect ratio;
can be either single wall nanotube or multiwalled tube.
Chemical vapor deposition (CVD)
Vapor phase technique commonly used in microelectronics to prepare thin films of silicon,
dielectrics and other materials on substrates; adapted to grow carbon nanotubes with the aid
of catalysts such as iron or nickel.
Plasma enhanced chemical vapor deposition (PECVD)
A variation of CVD wherein the energy for chemical reactions is supplied via energetic
electrons instead of the high thermal energy supplied in conventional CVD.
Inorganic nanowire
Cylindrical nanowire of any inorganic material: element, compound, oxide, nitride, etc.
Quantum dot
A synthetic 'cluster' or 'droplet' containing anything from a single electron to a collection of
atoms but behaves like a single huge atom; also called a zero-dimensional material.
DendrimerA tree-like polymer with a central core and branches which is characterized by large
molecular weight and investigated for gene therapy and drug delivery.
Scanning tunneling microscope
An instrument capable of directly obtaining three-dimensional images of solid surfaces with
atomic scale resolution.
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References
Nanoscale Materials in Chemistry, Editor: K.J. Klabunde, Wiley Interscience (2001).
www.nano.gov, a U.S. Government website from the U.S. National Nanotechnology
Coordination Office.
www.nclt.us, a website from the National Center for Learning and Teaching Nanotechnology
at Northwestern University, Evanston, IL.
Handbook of Nanotechnology, Editor: B. Bhushan, Springer, New York (2004).
Carbon Nanotubes: Science and Applications, Editor: M. Meyyappan, CRC Press, Boca
Raton, FL (2004).
M. Meyyappan and M. Sunkara, Inorganic Nanowires, CRC Press, Boca Raton, FL (2009).
Nanoscale Science and Engineering Education, Editors: A.E. Sweeney and S. Seal,
American Scientific Publishers (2008).
Nanoelectronics and Information Technology, Editor: R. Waser, Wiley-VCH (2003).
Biological and Biomedical Nanotechnology, Editors: A.P. Lee and L.J. Lee, Springer (2006).