[MUSIC]
Hi, welcome to lecture 2 of week 1 in
Coursera's nanotechnology the basics.
I'm Vicki Colvin.
What we're going to be doing in the second
lecture is talking about the definition of
nanotechnology.
There are a lot of diverse perspectives on
nanotechnology as we'll briefly discuss.
And the actual definition of
nanotechnology will
vary from country to country and agency
to agency, but there's some common
elements
that are pretty much always present when
people define nanotechnology.
And finally, I want to just clarify some
of the terms like
nanomaterial and how nanotechnology may
relate
to nanoscale device structures as well.
So I want you to take a moment to look at
this slide.
On the left are some quotes from people
about what they think nanotechnology is.
And on the right, are the identities of
the
people who said them, except they don't
match up.
So as you peruse the, the definitions and
concepts, I want you to guess who said
what.
So for example, what do you think the
entrepreneur said about nanotechnology.
What do you think the older professor
said?
So, what this really represents is kind of
the diversity
of viewpoints about what nanotechnology
means to different kinds of people.
So when you say definition of a subject,
there's of
course the formal definition, which we'll
get to in a moment.
But there's also the informal ways that
people understand
the term and what it may mean to them.
So just to not leave you hanging, here's
the identities.
So, these really interesting and unique
perspectives are
ones that may be held by you the viewer.
So go ahead and take our provocative
survey this week.
On to more formal definitions.
So ASTM is in an international standards
organization, and in 2006 I
worked with them and about a 150 people on
a committee to
define nanotechnology, which was an
interesting process in and of itself.
But ,t we came up with is shown here and
this
is pretty much, got the basic elements of
the definitions of nanotechnology.
You'll see from the international
standards organization, many EU countries
as
well as, as you'll see in a moment, the US
government.
So let's sort of dissect this definition
into its unique parts.
First of all,
the most important thing is that
nanotechnology refers to technologies that
incorporate materials.
Nanotechnology is a materials based
technology.
It's all about the stuff that's in
something that makes it nanotechnology.
Second most important thing is the length
scale.
I love this, approximately, about on the
order of.
You'll see those caveats in a lot of
definitions.
So you get the 1 to 100 nanometers
for a critical dimension.
But you also get the about the
approximately the hedging modifiers.
So, we don't really want to pin down a
specific length scale, but we want to
provide loose boundaries, which are 1 to
100
nanometers, for where most nanoscale
materials will fall.
And finally, a unique feature of the ASTM
definition, that actually
you'll find in many others, including the
ISO definition, is the observation
that on this length scale, materials act
differently.
So if you just randomly ground up a bunch
of sand to be a 100 nanometers, and
incorporated it
for no actual purpose and didn't take
advantage of
that small scale size, it may not be
considered nanotechnology.
They're sort of this issue of intent,
present in this definition.
But the reality is, that nanomaterials
often
behave very differently than their bulk
counterparts.
And some of the most powerful
nanotechnologies exploit
that fact directly.
If you want to boil down this definition,
I say nanotechnology contains stuff that's
small and strange.
Let's turn to the U.S. definition.
So, the National Nanotechnology Initiative
also defines nanotechnology.
I'll let you read this and think about the
last definition.
What you'll notice is some similarities,
the 1 to
100 nanometer length scale, and that ever
present hedging word,
in this case about.
But what you'll notice is the absence in
specifying that nanotechnology must
exploit materials with unique properties.
That's one of the ways this definition is
a little bit different than the last one.
But the reality is if something is on this
length
scale of 1 to 100 nanometers, it often is
very different.
So whether you specify that or don't, may
be a moot point.
Nevertheless, you can see some of the
similarities.
And also in both definitions,
the recognition that it's a very, very
broad area, touching, touching a lot if
industries.
A couple of other points to make.
Because nanotechnology can be embedded in
a
lot of different kinds of devices, I want
to just make clear the difference between
materials, device and the technology at
the end.
So, silicon for example, can be used to
be, make microprocessors,
which show up in your cell phone or your
iPad, the technology.
In the same
way, a nanomaterial.
In the same way a nonomaterial could
exhibit a lot of different properties,
being incorporated into a device or not,
and then show up in a
final product as shown here in a light
emitting diode where it makes
the color of the diode much warmer than
the typical blue LED color.
So in that sense the nonmaterial is
material side.
And the nanotechnology is after you've
incorporated it into,
usually a larger system of some sort.
The next important thing I want to point
out in
this definitions lecture is that
nanomaterials is a broad term.
There's a lot of different kinds
of materials that can be considered
nanomaterials.
So you can have iron oxide
that's nanoscale, that has unique magnetic
properties.
You can even have cadmium selenide, which
is a quantum dot.
Shown here is a blow-out of lots of little
quantum dots, so you're looking at lots of
individual particles.
These materials have size-dependent color
and that can be utilized
for example, in the last example of the
light-emitting diode.
And you can even have nanoscale carbons.
So unlike the Iron Age or the Bronze Age,
where we
learned about a specific type of material
and then we used that.
Nanotechnology is going to utilize our
understanding
of almost every material, but our
understanding specifically
of what happens to it on the nanometer
scale.
So it's extremely broad in the types of
materials you'll learn about.
So those are some of the points I wanted
to make in this definition lecture.
Really it's this concept that
nanotechnology is really
unique whatever the definitions say,
because for the first
time perhaps in human history, we're not
really
concerned with the composition of the
materials that we're
going to use.
We're concerned with the size of
the materials, the dimensions that we've
constructed.
Gold will behave completely differently on
the nanoscale, so will many other
materials.
So composition becomes secondary to the
dimensions of the solid.
And that's one of the things about
nanotechnology that is truly different.
It isn't necessarily captured in the
definitions, but I want to have in your
head when you think about it relative to
some of these other technology areas.
So some of your points from this lecture I
want you to take away.
There are formal definitions of
nanotechnology, they all specify 1
to 100 nanometers with the qualification
of about or approximately.
They all talk about how it's a materials
technology and
some of them point out there could be
unique features.
Finally the term nanomaterials refers to a
very broad class of materials.
And it doesn't tell you that it's about
carbon or about gold
but more about the size of the material.
Thanks so much, and I'll see you next
time.