intro nano

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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

IEEE Expert Now Introduction to Nanotechnology Transcript pg. 2 / 21

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


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


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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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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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?

8/3/2019 Intro Nano


Glossary


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.

8/3/2019 Intro Nano


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).

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