(light music) - Hey, smart people.
Joe here, and this is Vanilla Bean.
Vanilla Bean is a gecko.
Now, I've always wanted to do this.
Okay, little buddy.
Time to do your thing.
No pressure, just like the whole world watching.
Look at that.
Geckos have this incredible ability to stick to just about any surface.
I mean, hanging upside down from glass, walking up walls.
I mean, it's amazing.
They can cling tight enough to do this, yet let go with almost no effort.
And they can do this again and again and again, and their grip never wears out.
Take a look at their feet, though.
It's not exactly obvious how they do this.
Well, today, we're going to investigate that, and we're going to get really up close and personal with this guy or gal's feet, I can't tell which, and we are going to figure out how they use physics to create that extreme grip, and how it's inspiring scientists to create new materials with incredible gripping properties that are inspired by nature.
All right, stick around.
(laughs) (crickets chirping) Get it?
Stick-- Stick around.
(gentle music) Walking up walls would be awesome.
I mean, think about it.
I could be like a secret agent, or a jewel thief, a superhero.
Unfortunately, it's a little bit harder than it looks, but geckos can do that.
Of course, they've had hundreds of millions of years to perfect their skills.
Of the 1500 or so gecko species on earth, about 60% can wall walk, and people have been amazed by this for thousands of years.
I mean, maybe you've heard of a guy named Aristotle.
Well, he was like the smartest guy alive during his time, and even he was stumped by what a gecko can do.
Take a look at their feet.
We used to think the secret was those deep ridges here on their toes.
Kind of makes you think of our fingerprints, right?
Well, they don't secrete anything sticky, like snails or tree frogs.
Well, maybe geckos push down on those ridges to create suction, like an octopus or something.
Or maybe like insects, they use them like microscopic fingers to grab onto a surface.
Well, the answer is cooler than any of those.
See, here's the thing.
Geckos can even cling to surfaces that are completely smooth, and we're talking smooth down to the molecular scale.
To figure out what's going on, we're going to need to look closer.
These images were created using an electron microscope, and they show us that a gecko toe pad is covered in about half a million tiny hairs called Setae.
Now zoom in even closer, and each of those hairs is covered with hundreds of tiny little bristles that kind of look like spatulas.
Well, those tiny little bristles, they let a gecko's toes make contact with the surface it's climbing on on the nanoscale.
We're talking billionths of a meter.
And when you think about climbing, you think about things like, I don't know, friction and gravity, but on the nanoscale, different forces take over than what we're used to, and this is where it gets awesome.
A gecko can climb because the molecules in their feet are directly interacting with the molecules of what they're climbing on.
That leads to a special kind of attractive force called Van Der Waals Force.
Now you might say, "that's what lets geckos climb 'Der Waals.'"
(laughs) You're never going to laugh at my jokes.
Okay.
So what does that mean?
So we're used to two oppositely charged things, or things with opposite polarity attracting.
You know, like the ends of a magnet.
Well, a gecko's feet aren't charged, and the surfaces that they walk on aren't charged, but they're able to use the same principle of attraction thanks to a very strange phenomenon down on the atomic scale.
Now, the atoms that make up the surface and the atoms in a gecko's foot have positive nuclei and negative electrons.
Now usually, those all cancel out, because an atom with the same number of electrons and protons is basically neutral.
But electrons are always moving around, and every so often, they can end up more on one side of the nucleus than the other, just like planets in the solar system can be occasionally more on one side of the sun.
So that side becomes more electron dense, and it gets a slight negative charge.
The other side has a slight positive charge.
This is called a dipole.
And if another atom comes close enough in that moment, it can get a slight negative and positive imbalance too.
And those slight opposite charges stick.
I mean, that's crazy.
Tiny little changes to where electrons are can create a little sticky force between two atoms.
And if we put the gecko on a surface that can't contribute to Van Der Waals Forces, like a nonstick pan or something, well, the gecko can't grip.
These Van Der Waals Forces are really weak, and they only work at those tiny nanoscale distances, but they can really add up.
Holding this gecko on my hand, that weight is somewhere around one newton or less of force pushing down.
But each of those microscopic bristles on its toes, they provide less than one 1 millionth of a newton of attractive force.
But a gecko has over a billion of those tow bristles, and added up, that's enough force to hold many times their body weight, just from the attraction between atoms.
Now, you're smart.
So I know what you're thinking.
If that attraction is so strong, then how do they let go whenever they want to?
Well, a gecko has the ability to align all of those millions of microscopic hairs using muscles and tendons in their feet and maximize their grip.
Sort of like how the muscles in my hand create tension on my fingers and help me palm this ball.
Are you impressed?
(laughs) Remove that tension in my hand, and... (ball clatters) By the way, that was a kid's soccer ball.
I'm not some sort of weird giant.
The same way, just changing the angle that their toe bristles touch the surface, geckos' Van Der Waals grip, it disappears in milliseconds.
Now, stickiness and grippiness is a big deal to scientists.
If you've ever tried to move and re-stick a post-it note more than a couple of times, you know that one of the problems with any reusable sticky thing is that it eventually wears out.
But gecko feet never lose their grip, no matter how many times they are stuck and unstuck.
Now, by studying how geckos grip onto surfaces on the nanoscale, engineers have created biologically inspired materials like this gecko inspired tape.
Now, this is covered in thousands of tiny little hairs, a lot like the gecko's foot, and that stiff backing, it acts just like the muscles and tendons in a gecko foot.
There's no glue on this surface, but it can grip things super tight.
I mean, just watch this.
Vanilla Bean, are you impressed?
This is all thanks to the molecular gripping between this surface and the glass on a scale of billionths of a meter.
And I can remove it over and over again, and it will never lose that grippiness.
- Hi, Phil Swift here for-- - Gecko feet.
It's like a post-it note developed by millions of years of evolution and natural selection.
Geckos use some pretty amazing nanotechnology.
It makes you wonder if we could be like Spider-Man if we had hands or gloves like this.
Well, I hate to disappoint you, but no.
You might remember this rule in biology where as an organism gets bigger, our mass goes up by a power of three, and our surface area only goes up by a power of two.
We would need most of our body covered in Van Der Waals grippers just to hang on.
And that is why there's no 50 pound geckos around, which I'm pretty thankful for, because you are much cuter this size.
All right.
Stay curious.
New show mascot?
I don't know.
I think you're going to get some new fans, Vanilla Bean.
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