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[MUSIC]

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Hi, welcome to lecture 2 of week 1 in
Coursera's nanotechnology the basics.

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I'm Vicki Colvin.

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What we're going to be doing in the second

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lecture is talking about the definition of
nanotechnology.

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There are a lot of diverse perspectives on
nanotechnology as we'll briefly discuss.

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And the actual definition of
nanotechnology will

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vary from country to country and agency

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to agency, but there's some common
elements

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that are pretty much always present when

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people define nanotechnology.

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And finally, I want to just clarify some
of the terms like

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nanomaterial and how nanotechnology may
relate

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to nanoscale device structures as well.

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So I want you to take a moment to look at
this slide.

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On the left are some quotes from people
about what they think nanotechnology is.

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And on the right, are the identities of
the

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people who said them, except they don't
match up.

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So as you peruse the, the definitions and

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concepts, I want you to guess who said
what.

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So for example, what do you think the
entrepreneur said about nanotechnology.

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What do you think the older professor
said?

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So, what this really represents is kind of
the diversity

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of viewpoints about what nanotechnology
means to different kinds of people.

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So when you say definition of a subject,
there's of

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course the formal definition, which we'll
get to in a moment.

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But there's also the informal ways that
people understand

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the term and what it may mean to them.

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So just to not leave you hanging, here's
the identities.

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So, these really interesting and unique
perspectives are

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ones that may be held by you the viewer.

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So go ahead and take our provocative
survey this week.

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On to more formal definitions.

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So ASTM is in an international standards
organization, and in 2006 I

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worked with them and about a 150 people on
a committee to

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define nanotechnology, which was an
interesting process in and of itself.

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But ,t we came up with is shown here and
this

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is pretty much, got the basic elements of
the definitions of nanotechnology.

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You'll see from the international

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standards organization, many EU countries
as

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well as, as you'll see in a moment, the US
government.

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So let's sort of dissect this definition
into its unique parts.

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First of all,

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the most important thing is that

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nanotechnology refers to technologies that
incorporate materials.

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Nanotechnology is a materials based
technology.

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It's all about the stuff that's in
something that makes it nanotechnology.

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Second most important thing is the length
scale.

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I love this, approximately, about on the
order of.

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You'll see those caveats in a lot of
definitions.

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So you get the 1 to 100 nanometers

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for a critical dimension.

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But you also get the about the
approximately the hedging modifiers.

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So, we don't really want to pin down a
specific length scale, but we want to

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provide loose boundaries, which are 1 to
100

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nanometers, for where most nanoscale
materials will fall.

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And finally, a unique feature of the ASTM
definition, that actually

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you'll find in many others, including the
ISO definition, is the observation

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that on this length scale, materials act
differently.

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So if you just randomly ground up a bunch

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of sand to be a 100 nanometers, and
incorporated it

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for no actual purpose and didn't take
advantage of

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that small scale size, it may not be
considered nanotechnology.

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They're sort of this issue of intent,
present in this definition.

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But the reality is, that nanomaterials
often

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behave very differently than their bulk
counterparts.

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And some of the most powerful
nanotechnologies exploit

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that fact directly.

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If you want to boil down this definition,

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I say nanotechnology contains stuff that's
small and strange.

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Let's turn to the U.S. definition.

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So, the National Nanotechnology Initiative
also defines nanotechnology.

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I'll let you read this and think about the
last definition.

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What you'll notice is some similarities,
the 1 to

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100 nanometer length scale, and that ever
present hedging word,

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in this case about.

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But what you'll notice is the absence in

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specifying that nanotechnology must
exploit materials with unique properties.

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That's one of the ways this definition is
a little bit different than the last one.

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But the reality is if something is on this
length

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scale of 1 to 100 nanometers, it often is
very different.

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So whether you specify that or don't, may
be a moot point.

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Nevertheless, you can see some of the
similarities.

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And also in both definitions,

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the recognition that it's a very, very

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broad area, touching, touching a lot if
industries.

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A couple of other points to make.

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Because nanotechnology can be embedded in
a

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lot of different kinds of devices, I want

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to just make clear the difference between

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materials, device and the technology at
the end.

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So, silicon for example, can be used to
be, make microprocessors,

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which show up in your cell phone or your
iPad, the technology.

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In the same

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way, a nanomaterial.

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In the same way a nonomaterial could
exhibit a lot of different properties,

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being incorporated into a device or not,
and then show up in a

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final product as shown here in a light
emitting diode where it makes

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the color of the diode much warmer than
the typical blue LED color.

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So in that sense the nonmaterial is
material side.

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And the nanotechnology is after you've
incorporated it into,

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usually a larger system of some sort.

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The next important thing I want to point
out in

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this definitions lecture is that
nanomaterials is a broad term.

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There's a lot of different kinds

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of materials that can be considered
nanomaterials.

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So you can have iron oxide

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that's nanoscale, that has unique magnetic
properties.

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You can even have cadmium selenide, which
is a quantum dot.

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Shown here is a blow-out of lots of little

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quantum dots, so you're looking at lots of
individual particles.

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These materials have size-dependent color
and that can be utilized

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for example, in the last example of the
light-emitting diode.

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And you can even have nanoscale carbons.

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So unlike the Iron Age or the Bronze Age,
where we

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learned about a specific type of material
and then we used that.

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Nanotechnology is going to utilize our
understanding

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of almost every material, but our
understanding specifically

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of what happens to it on the nanometer
scale.

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So it's extremely broad in the types of
materials you'll learn about.

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So those are some of the points I wanted
to make in this definition lecture.

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Really it's this concept that
nanotechnology is really

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unique whatever the definitions say,
because for the first

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time perhaps in human history, we're not
really

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concerned with the composition of the
materials that we're

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going to use.

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We're concerned with the size of

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the materials, the dimensions that we've
constructed.

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Gold will behave completely differently on

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the nanoscale, so will many other
materials.

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So composition becomes secondary to the
dimensions of the solid.

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And that's one of the things about
nanotechnology that is truly different.

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It isn't necessarily captured in the
definitions, but I want to have in your

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head when you think about it relative to
some of these other technology areas.

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So some of your points from this lecture I
want you to take away.

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There are formal definitions of
nanotechnology, they all specify 1

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to 100 nanometers with the qualification
of about or approximately.

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They all talk about how it's a materials
technology and

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some of them point out there could be
unique features.

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Finally the term nanomaterials refers to a
very broad class of materials.

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And it doesn't tell you that it's about
carbon or about gold

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but more about the size of the material.

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Thanks so much, and I'll see you next
time.