07x04 - Forces at the Nanoscale

[bunniefuu]

This time on Dragonfly TV Nano, we're

climbing the walls with geckos. Like he's

dancing. Getting all wet with

nasturtiums. It does not get wet. And

creating a nano traffic jam.

Major funding for Dragonfly TV is

provided by

the National Science Foundation,

supporting education and research across

all fields of science and engineering.

The National Science Foundation, where

discoveries begin.

Dragonfly TV. Dragonfly

TV.

This is Dragonfly TV Nano, and I'm Eric.

Every time I jump up, the force that

brings me back down is gravity.

Otherwise, each bounce would send me

flying.

Without gravity, a lot of fun things

wouldn't work the same way. But what if I

were smaller?

We experience gravity all the time, but

at the nano scale,It's barely

noticeable. See what I mean?

At the nanoscale, other forces are more

important. The world is very different in

Nanoland. Scientists say it's sticky,

bumpy and shaky. That doesn't sound like

science, right?Sounds more like a new

hip hop dance.

Actually, sticky, bumpy, and shaky

explain the way some things work at the

nano scale. Let's take sticky.

Meet Jasper. Hey

Jasper, this is your big break, so just

stay cool and be yourself.

This is Jasper. He's a crested

gecko who is a great climber,

and he uses nano every time he

climbs. Sounds mysterious, right?

Well, sit tight, because Jennifer and

Nushin are after his secret. Go,

buddy, go.

I'm Jennifer, and this is Nushin. We love

to climb rocks, but we're not the only

ones up here. Lissas love climbing, too,

and they're really good at it. We're

going to go try to find some.

Did

you find any yet?Nope,

not yet. I

couldn't

find anything. Maybe my guide bro custom

tips. Yeah.

Cool. Where'd you get this?I got thorny

here at the museum store, and I know

where we can find some lizards for sure.

We headed to the Lawrence Hall of

Science, where they've got lots of

lizards and other cool stuff. Cool, the

nano zone.

You are five foot three. You are



nanometers. At the Lawrence Hall of

Science, we can get our hands on real

live lizards. We need to take a closer

look to figure out how they can climb so

well. Hi. HiI'm Nation. I'm Alondra.

Would you guys like to check out some

lizards?Yeah. Check this out.

We have leopard geckos and a

Uromastyx. Oh, cool.

They're crested geckos. This is a bearded

dragon. We were looking for some lizards

at our favorite climbing rocks, but

couldn't find any today. Can you tell us

if any of these lizards are good climbers?

You can test them and find out.

Let's make a chart of which lizards are

the best climbers. Well, what do we need

on the chart?Well, one can be for what

kind of lizard they are. Two can be for

what kind of feet they have. And three

can be how well they climb.

Can we test the desert iguana first?Sure.

Let me show you how to hold it. You just

want to pick it up very gently and

support its entire body, OK?Nice. Real

nice. Let's put this little guy in our

test tank and see how well he can climb.

Yeah. Wow, wow, wow,

wowI think he likes the rock better.

Yeah. It was fun to hang around, but I

really must be going. It's like he's

dancing. Let me out of here. He's not

sticking too well to the glass. I don't

think he's a great climber. So Jen, what

do his feet look like?He has pretty long

toes, and his nails are pretty sharp at

the end of it.

I've got the crusted gecko. Cool. Put him

in.

He's sticking to it. He's got his really

sticky feet. His feet kind of look like

he have lines on him, and he has really

short claws. Wanna be a tree climber?

Wanna be a tree

climber?Next up, the gargoyle

gecko. Looks like he sticks pretty

well. This guy can climb right up the

glass. Oh, look, he's climbing the log.

This guy's a good climber. This is the

fat tail. Look how

small his little hands are. They're

really, really tiny, and they're not

webbed at all. He's slow.

Not a climber. Oh, I'm having too much

fun! I'm very busy. Please,

go away. We ranked our lizards and put

pictures of the worst climbers at the

bottom and the best climbers at the top.

So the desert iguana could climb on

rocks, but not the glass. The fat-tailed

gecko is not a climber. The crested gecko

sticks really well. The gargoyle gecko

also sticks and climbs. The two best

climbers are both geckos. Maybe it has

something to do with their feet. Yeah.

Hey, Alondra, our experiment showed that

the geckos were the best climbers. Is

there anything special about geckos?Yeah,

it involves forces on the nanoscale.

You should check out the Gecko Tech

exhibit. Cool, let's go.

Hey, let's look over here. This is making

the gecko move. So awesome.

The exhibit showed us why some geckos are

such good climbers. By peeling toe hairs,

starting from one end of each toe, geckos

gradually reduce their strong clinging

force. Uh-huh

We just learned a bunch of cool stuff,

but we want to know more about the nano

hairs on gecko feet. You should visit Bob

Kool at UC Berkeley. OK, thanks.

So Nooshin and Jennifer just found out

that millions of microscopic hairs, or

setae, on gecko feet make them sticky,

but not sticky like glue. The force that

holds the gecko toe hairs to the wall

is not that strong, but there is power

in numbers, which means sticky

wins out over gravity. In fact,

geckos can hang upside down on polished

glass by a single toe. Now

that sounds hard.

OK, you special effects

guys are really funny. Ha

ha. I'm not a gecko.

Even though I know a lot about them. For

instance, did you know that most geckos

don't have eyelids?They just lick their

eye membranes instead.

OK, can I get down now,

please?

Thank you. You're welcome.

Now, today's nano challenge is.

If a gecko could use every one of its

setae or tiny hairs on all four

feet, how much weight could it hold and

still stay stuck to the ceiling?

Could it hold A a

teddy bear, BA watermelon, CA



panda?I want you to think seriously

hard about this, and I'll be back with a

clue later on. Now back to Jennifer and

Nushin and Bob's crested geckos.

I like lizards and geckos because they're

just so cool and I think they're really

cute. So. I'm not scared of them at all.

You can, you know, put a bunch on me in

the middle. I'll be like, OK. I'll be

like, yeah. Geckos rule.

Salon just sent us to see Bob Full at UC

Berkeley. I'm Misha. Nice to meet you. We

work on geckos. One of them is running on

the ground and one of them is running up

a wall. The question is, how do they do

it?What they do is they use bizarre toes.

Let's look at the toes more carefully to

see how they stick. So they have these

leaf-like structures and we can zoom in

on them. And what you see is they look

like this. It looks like a rug, doesn't

it?It's really strange. And then we can

zoom in and look at the individual hairs.

And then we can even zoom in further and

look at the tips of the hairs. We find

the secret of how they're sticky. And

that is, they have the worst case of

split ends possible, about 100 to 1,000

split ends. And they're really small.

They're nano-sized, and a gecko has about

a billion of those nano-sized tips. What

I'd like to do today is take you

downstairs and show you on some real live

geckos.

Here's one of our subjects. This is a

crested gecko. We're going to put the

gecko on glass and we're going to use the

high speed camera that can capture up to



goes. OK, record it.

There's the animal's toes. So how do

their feet stick and unstick so quickly?

It does it in milliseconds and

thousandths of a second, and it kind of

uses its toes like a party favor, like a

New Year's when you blow it out, it

uncurls and then it peels up. But it does

it really quickly. So how come when I

walk, I pick up my heels first, but they

go toes first?Well, they have these

sticky hairs and what they need to do is

to change the angle of the hair so they

peel off. And they do that with their

toes and they curl them back like that,

but that allows them to peel off. and run

up a wall or a tree really fast.

Bob introduced us to Ron Fearing, who has

developed a special kind of tape that

mimics the nanohairs in gecko feet. So

we've been taking the knowledge that

Bob's generated from studying the geckos,

and we've been building a synthetic gecko

tape. Why don't you feel it?Tell me what

you feel. It's very soft. It's soft, but

does it feel sticky?No. So one of the

interesting things is it's not sticky

unless you actually apply it to a surface

and pull it. So how does your

gecko tape differ from regular tape?This

is 1000 times scale model. If I press

into the surface, the fibers just kind of

press off so it's not sticky at all. But

if I slide it like this, what what

happens?It bends. It bends and now the

fibers have a lot of contact and so we

actually get adhesion. Cool. Where can we

get some gecko tape?Well, it's not in the

storage yet, but I've made you some gecko

tape. Oh, cool. Thanks. Thanks. You're

welcome. Come on, Nishan. Let's go back

to the rocks and show those listeners our

gecko tape.

This gecko tape is some cool stuff.

Imagine the possibilities. Yeah, if we

had it all over our hands, we would go

out straight up the rocks. Everything

possible in here We were

just bloody Then we can

succeed

Those girls are on to something. Nature's

inventions are endless. Now you'd

think that sticky gecko feet would get

dirty fast. But guess what?Gecko feet

are self-cleaning. But that's a story for

another time. Next up, we'll meet Jason,

who deals with the world of sticky and

shaky when he designs nano-sized cars.

For example, does a nano car stick so

much that it can't move?Or does it

shake a lot when you drive it?Check this

out.

Let's go. Hi, I'm Jason and I'm a nano

car engineer. Now, the cars that I make

are about a billion times smaller than

this one. That means that I take tiny

molecules and I make them into cars at

the nano scale. These nano machines, they

actually have pieces that behave a

lot like a regular car would. This is

actually a toy model of a nano car. So

just like a real car, it has four wheels,

axles, and a middle chassis portion. When

we put it on the surface, the nano car

actually rolls along just like a real

car. The way I put

my nano cars togetheris with chemistry.

It's called chemistry.

This is chemistry. But unlike big cars

that are put together with nuts and

bolts, I put my nano cars together by

doing chemical reactions.

So the reason that I work on nano cars is

because hopefully one day, we'll be able

to make nano machines. What we're trying

to learn is how we can controlSingle

molecules to get them to perform a

certain function. So we're at the very

low levels and very fundamental research

right now. Maybe one day there can even

be nano machines that you can put in your

body so that when you're sick, it can

help get you better. There are more nano

cars in this little bottle than there

have ever been real cars on the roads

ever. Believe it or not, there are

actually 1 billion billion

nano cars in this bottle.

Oh no, I think I just created the

world's. Worst traffic jam ever.

This is our glove box we can. All the

chemicals that we need together and run

the reaction inside the box.

It's really nice being able to have

friends in the lab that you can share

ideas with and you have those friends to

pick you up and tell you hey. Try again,

and eventually it it will all work out.

My wife and I have been married for

about three and a half years now.

Thankfully, she also shares some of the

passions that I do, like working out and

play Rock Band and Guitar Hero.

Jason has a pretty cool job. And who

knows, maybe someday there will be nano

video games where players move real

nanoparticles around. Nano Sims,

anyone?For now, check out the cool

Nanobots game on the Dragonfly TV

website. And in the meantime, here's

another way to get a nano-sized view of

the world. Taxi!

All right, Zoomer, you ready to go?

What's that toothpaste smell?You're

right, Zoomer. This is a mint leaf,

and those veins right there bring SAP up

into the leaf. And you see those hairs?

They help the leaf hold on to its water.

And what is with all these bubbles?

Well, those are where the mint smell

comes from. Whenever a bubble breaks,

minty fresh. Let's zoom in a little

closer.

You remember sticky, bumpy, shaky?Well,

it is really bumpy here on the leaf's

surface, even though to us it looks and

feels pretty smooth. Now let's zoom a

little closer, shall we?

Now we're magnified 8000

times, and inside here we

find the chlorophyll, which makes the

leaf green. It's stored in those egg

shapes right there. But let's zoom in

even closer.

Wow. WowIt looks

like a cave painting down here at the

nanoscale. See those striped

bands?They are one nanometer

wide. And this. Is the heart of the

operation where carbon dioxide is

converted into oxygen. Oh,

I know, Zoomer. You can't go past the

nano-size. Let's get on out of here.

Yeah! Watch out behind!

Now, from the mint leaf to the garden.

Next up, Jasmine and Melinda find out

which leaves make the best umbrella.

I don't think it's this leaf.

I fell asleep and made the flowers

For a couple of hours

Hi, my name is Jasmine, and I'm a

volunteer here at the Botanical Gardens.

And I'm Melinda. I help her out

sometimes. One of my jobs here is to

water plants. All living plants require

water. And I've noticed that not all

leaves react to water the same way. Hey,

Jess, come check this one out. Hey,

what's up?Ooh, purple leaves. You are so

cute. Hey, look at this one. The water

beads up on it. I've noticed not all

leaves are like that. Some of them just

slip water right up. Excuse me?Yeah. Can

you tell us what plants these are and why

the water beads up like that?They're

nasturtiums. Wait, nastur-what?They're

nasturtiums. Oh, nasturtiums. We

were curious about why some leaves caused

water to beat up and some didn't. And we

knew just the place to go to find the

answer. Hey, where's everyone going?We're

at the Exploratorium. You get to answer

your science questions on your own.

These are the plants that we saw in the

park. They're the tertiums. The tertiums?

Oh, ohh right. Water doesn't even stand

there. It's waterproof, you know?It's

completely dry, not wet at all. It's not

limp or anything. Like those salads that

are overdosed with salad dressing.

This would be a good shower cap. I

wonder why the water beads up on the

leaf and then rolls off. You

know what would be really cool?What?The

nasturtium umbrella. Introducing the

nasturtium umbrella. Be the envy of all

your friends by being the first to own

this stylish nasturtium umbrella. Comes

in green, green, and green. Order now.

We love our deserts of umbrella. Offer

subject to availability. This product

does not exist. A photo of the leaf

showed that it's covered with tiny, tiny

hairs, like the hairs on our skin. They

beat up in little circles, but not nearly

as much as the plants. The hair of the

leaves are so much tinier. That's why

they act different. Another

exhibit projected images that acted just

like real water droplets. The exhibit

makes your shadow as small as you'd be

next to a real water droplet.

We wondered if we could pretend to be a

nasturtium leaf. Hey, can you guys help?

Sure. All right. So first we're gonna

kneel down and put your hands up.

Together, we made the drop roll over our

fingertips, just like nanohairs.

That's awesome. Water is so cool. Let's

find out more. Yeah, let's go. Being in

the search of leaf is fun. We met Paul, a

scientist who works at the Exploratorium.

He told us why the water droplets don't

make the leaf wet. The liquid is held

together by something called surface

tension. Water molecules love each other.

They really like water molecules more

than anything else, and they bond

together. I love you, man. I love you

too, bro. We got to stick together. But

water molecules don't like waxy things,

and so there are hairs on the surface of

this leaf. That water molecules don't

grab. I'm not grabbing you. I'm not

grabbing you. But they grab each other

and so they stay together as they roll

around. Is there a way to see the same

effect on a larger scale?I have some

coins, some metal coins, and you can

float them. Whoa, whoa. The surface

tension was so strong that it kept the

coins from sinking. I wonder if plants

deal with water the same way. We could

test them and find out. I have something

else for you to compare. Scientists have

created materials that mimic the way

plants shed water. I have cotton and

nanopants materials for you to compare

with your plants. Thanks, Paul. Let's go

wrangle some plants. Yeah. We

headed back to the botanical gardens to

gather up some plants for our test.

OK, we have everything here to compare

the plants. We found a nasturtium, a

geranium, a sunflower, a begonia,

and a lamb's ear. Let's figure out what

we need to test and keep track of. We

should start with the basics, what they

look like and what they feel like. Then

we can wet them and see how they react.

To test the leaves, first we dropped

water on each one, and then we dunked

them. We made a table on our notebook to

record the results. Let's start with a

nasturtium plant. The top feels

smooth. I don't see any hairs, not

even with the magnifying glass. The water

ba*ls up and just glides over it.

Submerge them in water, and it does

not get wet at all. The leaves,

Looks somewhat hairy. It's

soaked. It doesn't marble up like

roosterchums. It feels like fine-grain

sandpaper. It gets completely wet.

They're more oval than round.

Begonias are really hairy. It gets

really, really wet. The water droplets

flatten out. There's lots of hairs in

multiple layers. The hairiness of the

leaf captures the moisture. The

drops become round. We discovered that

more hairs closer together caused the

water to bead up, like the nasturtium and

the land's ear. But in the dunk test, the

nasturtium was the only plant that didn't

get soaked. This is the part I'm really

looking forward to. We get to compare

these nanopants and the cotton fabric

with these natural leaves. Here's the

cotton. It feels very smooth. I'm

dropping water on it, and it soaks

through, and it gets completely wet.

Now for the nanopants. They feel soft.

The water just glides off like the

nasturtium leaf. Whoa!

The water rolled right off the nanopants.

I think there's something special about

this and the nasturtium leaf. We wanted

to take a closer look at the nasturtium

and the nanopants, so we were off to the

university where we heard that they had a

really powerful microscope. It's actually

called a scanning electron microscope,

and it allows you to see structure at the

nanoscale. We brought a nasturtium leaf

and nanofabrics to compare it to the

leaf. Marja helped us

prepare our samples. And here's the

scanning electron microscope, the SEM

itself. All right, let's zoom in. Oh,

wow. Those little white hairs are

nano hairs, right?That's right. These

hairs look like they can send water

rolling right off. Yeah, they actually

look kind of waxy. That must be why

nasturtium sheds water so easily. Can we

see what our nano fabric looks like now?

Sure, let's give it a try. Marsha zoomed

in and showed us the fibers of the cloth.

Then she zoomed way in to the surface of

a single fiber. I don't actually see any

nanohairs. Does this mean the fabric

doesn't actually have nanohairs?It could

be just that the nanohairs are just so

small that our microscope is not powerful

enough to see them. This material might

be repelling water with a different

mechanism. Have fun, guys. Thanks for

everything.

Uh-huhWow, icy plants and it's totally

new right now. I can't wait to see what

happens when it rains.

Nasturtium hairs are a good reminder of

just how bumpy things can be on the nano

scale. But in nature there can be

both regular-sized and nano-sized bumps

in one place. Check out this

African beetle. The bumps on the

beetle's back actually snatch water out

of the bone dry desert air. The water

runs off these bumps down onto water

repellent channels and straight into the

beetle's mouth. Pretty handy system,

right?Scientists and engineers have had

good luck mimicking things in nature.

Here's a short list of things inspired by

nature. Submarines, airplanes,

Velcro, sticky notes. Wait a nanosecond.

Is it important to learn about things at

the nanoscale?Yeah,

definitely. It's a brand new thing. A

whole new world to discover. We'd be able

to do a lot of things that we haven't

done before. I don't know, I'm just a

kid. We can understand more about nature

and patterns and things like that, so we

can develop new and more interesting

technologies. Yep. I think it is

important to learn about nanotechnology

because it can help cure cancer. I'm

thinking. That's a hard question. It

concerns me that some bad things might

come out of nanotechnology. I

definitely think it's worth researching,

because if bad things do come out of it,

we have to understand what they are. It

seems like a really great thing that can

help a lot of people in the future. Well,

this just started, so... A

whole new world. Say that

again. Yes, we have a lot to learn.

Some pretty deep thinkers in that group.

So are you interested in the cool and

weird things happening on the nano scale?

We want to hear from you. Tell us what

you think. Here's how. Click on over to

the Dragonfly TV website at

pbskidsgo.org. Stream a cool

DFTV video. Try your hand at the new

Nanobots game, or tell us what you think

about nanotechnology. It's your place to

share your ideas.

So did the gecko challenge stump you?

It's time for the answer. If a gecko

could use every single one of its tiny

sticky hairs or setae, how much weight

could it hold?One more time.

A a teddy bear, BA watermelon.

CA10 year old or DA

giant panda. If you guessed

D, you're right. It's all of the above.

I'm getting to that. Using

all of its more than 6,000,000 setae or

hairs, a gecko could support anything

up to around 250 lbs.

That's 2000 times its own weight.

But. For the record, a gecko only uses a

small fraction of its setae, so don't

plan on taking a ride on one anytime

soon. Now, if only people could

climb walls like geckos, maybe someday

nanotechnology will make it happen.

See you next time on another nano-sized

edition of DFTV.

It's no mambo

It's the gecko tango

It's no ramba

It's the gecko tango Poros,

los, ohh

When you do the gecko tango

All the

Major funding for Dragonfly TV is

provided by...

The National Science Foundation.

Supporting education and research across

all fields of science and engineering.

The National Science Foundation. Where

discoveries begin.

PBS Kids!