TED@Merck KGaA, Darmstadt, Germany
Li Wei Tan: The fascinating science of bubbles, from soap to champagne
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In this whimsical talk and live demo, scientist Li Wei Tan shares the secrets of bubbles -- from their relentless pursuit of geometric perfection to their applications in medicine and shipping, where designers are creating more efficient vessels by mimicking the bubbles created by swimming penguins. Learn more about these mathematical marvels and tap into the magic hidden in the everyday world.
Li Wei Tan - Formulation scientist
As a formulation scientist, Li Wei Tan is constantly finding ways to understand why something works and why it doesn't. Full bio
As a formulation scientist, Li Wei Tan is constantly finding ways to understand why something works and why it doesn't. Full bio
Double-click the English transcript below to play the video.
00:12
Some years ago, I was visiting Paris
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and walking along the Seine River
during a beautiful summer afternoon.
during a beautiful summer afternoon.
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I saw giant bubbles
floating on the riverbank,
floating on the riverbank,
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like this one.
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The next moment, it popped and was gone.
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Making them were two street performers
surrounded by a crowd.
surrounded by a crowd.
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They visibly make a living
by asking for donations
by asking for donations
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and by selling pairs of sticks
tied with two strings.
tied with two strings.
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When I was there, a man bought
a pair of sticks for 10 euros,
a pair of sticks for 10 euros,
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which surprised me.
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I am a scientist who is
passionate about bubbles.
passionate about bubbles.
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I know the right trick
to make the giant bubbles
to make the giant bubbles
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is the right soapy water mixture itself --
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not the sticks,
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which may be needed,
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but you can easily make them at home.
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Focusing on the sticks makes us not see
that the real tool is the bubble itself.
that the real tool is the bubble itself.
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Bubbles might seem like something
just children make while playing,
just children make while playing,
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but sometimes it can be really stunning.
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However, there are more
fascinating science to bubbles,
fascinating science to bubbles,
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such as problem-solving tools.
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So I would like to share with you
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a few stories about
the science of creating bubbles
the science of creating bubbles
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and the science of eliminating
the microscopic ones.
the microscopic ones.
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Since it's up on the screen,
let's start with the soap bubble.
let's start with the soap bubble.
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It is made from very common substances:
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air, water, soap, in the right mixture.
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You can see soap bubbles
constantly changing their colors.
constantly changing their colors.
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This is due to the interaction with light
at various directions
at various directions
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and the changes of their thickness.
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One of the common substances,
water molecules,
water molecules,
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are formed by two atoms of hydrogen
and one atom of oxygen -- H2O.
and one atom of oxygen -- H2O.
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On most surfaces, water droplets
tend to curve inwards,
tend to curve inwards,
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forming a semihemisphere shape.
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This is because the water droplet's
surface is like an elastic sheet.
surface is like an elastic sheet.
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The water molecule on the surface
is constantly being pulled inwards
is constantly being pulled inwards
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by the molecule at the center.
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And the quality of the elasticity
is what we call "surface tension."
is what we call "surface tension."
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Now by adding soap,
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what happens is the soap molecule
reduces the surface tension of water,
reduces the surface tension of water,
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making it more elastic
and easier to form bubbles.
and easier to form bubbles.
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You can think of a bubble
as a mathematical problem-solver.
as a mathematical problem-solver.
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You see it relentlessly trying
to achieve geometry perfection.
to achieve geometry perfection.
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For instance, a sphere is the shape
with the least surface area
with the least surface area
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for a given volume.
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That's why a single bubble
is always in the shape of a sphere.
is always in the shape of a sphere.
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Let me show you. Check it out.
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This is a single bubble.
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When two bubbles touch each other,
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they can save materials
by sharing a common wall.
by sharing a common wall.
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When more and more bubbles
are added together,
are added together,
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their geometry changes.
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These four bubbles are added together.
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They meet at one point at the center.
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When six bubbles are added together,
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a magical cube appears at the center.
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(Applause)
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That is surface tension at work,
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trying to find the most effective
geometry arrangement.
geometry arrangement.
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Now, let me give you another example.
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This is a very simple prop.
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This is made from two layers of plastic
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with four pins connected to each other.
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Imagine these four pins represent
four cities that are equally apart,
four cities that are equally apart,
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and we would like to make roads
to connect these four cities.
to connect these four cities.
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My question is: What is the shortest
length to connect these four cities?
length to connect these four cities?
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Let's find out the answer
by dipping it into the soapy water.
by dipping it into the soapy water.
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Remember, the soap bubble forms
will always try to minimize
will always try to minimize
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their surface area
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with a perfect geometry arrangement.
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So the solution might not be
something you expected.
something you expected.
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The shortest length
to connect these four cities
to connect these four cities
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is 2.73 times the distance
between these two cities.
between these two cities.
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(Applause)
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Now you've got the idea.
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The soap bubble forms will always try
to minimize their surface area
to minimize their surface area
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with a perfect geometry arrangement.
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Now, let us look at bubbles
in another perspective.
in another perspective.
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My daughter, Zoe, loves visiting zoos.
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Her favorite spot is Penguin Cove
at Marwell Zoo in Southern England,
at Marwell Zoo in Southern England,
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where she could see penguins
swim at speed under the water.
swim at speed under the water.
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One day, she noticed
that the body of penguins
that the body of penguins
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leaves a trail of bubbles when they swim
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and asked why.
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Animals and birds like penguins
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that spend a lot of their time
under the water
under the water
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have evolved an ingenious way
of utilizing the capability of bubbles
of utilizing the capability of bubbles
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to reduce the density of water.
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Emperor penguins are thought to be able
to dive a few hundred meters
to dive a few hundred meters
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below the sea surface.
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They are thought to store
the air under their feathers
the air under their feathers
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before they dive
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and then progressively release it
as a cloud of bubbles.
as a cloud of bubbles.
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This reduces the density
of water surrounding them,
of water surrounding them,
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making it easier to swim through
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and speed up their swimming speed
at least 40 percent.
at least 40 percent.
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This feature has been noticed
by the ship manufacturers.
by the ship manufacturers.
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I am talking about the big ships here,
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the ones that are used to transport
thousands of containers across the ocean.
thousands of containers across the ocean.
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Recently, they developed a system
called "air lubricating system,"
called "air lubricating system,"
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inspired by the penguins.
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In this system, they produce
a lot of air bubbles
a lot of air bubbles
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and redistribute them across
the whole of the ship,
the whole of the ship,
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like an air carpet
that reduces the water resistance
that reduces the water resistance
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when a ship is moving.
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This feature cuts off the energy
consumption for the ship
consumption for the ship
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up to 15 percent.
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Bubbles can also be used for medicines.
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It can also play a role in medicines,
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for instance, as a method for noninvasive
delivery systems for drugs and genes
delivery systems for drugs and genes
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to a specific part of the body.
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Imagine a microbubble
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filled with a mixture
of drugs and magnetic agents
of drugs and magnetic agents
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being injected into our bloodstream.
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The bubbles will move to the target areas.
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But how do they know where to go?
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Because we placed a magnet there.
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For instance, this part of my hand.
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When the microbubbles
move to this part of my hand,
move to this part of my hand,
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we can pop it via ultrasound
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and release the drug
exactly where it's needed.
exactly where it's needed.
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Now, I mentioned about
the science of creating bubbles.
the science of creating bubbles.
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But sometimes we also need to remove them.
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That's actually part of my job.
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My exact job title is
"ink formulation scientist."
"ink formulation scientist."
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But I don't work on the ink
that you use for your writing pens.
that you use for your writing pens.
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I'm working on some cool applications
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such as organic photovoltaics, OPVs,
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and organic light-emitting diodes, OLEDs.
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Part of my job is to figure out
how and why we want to remove the bubbles
how and why we want to remove the bubbles
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from the ink that my company produces.
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During the formulation-mixing process,
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or preparation process,
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we mix active ingredients,
solvents and additives
solvents and additives
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in order to achieve the formulations
with the properties we want
with the properties we want
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when the ink is being used.
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But just like you would make drinks
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or bake cakes,
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it is unavoidable that some air bubbles
will be trapped inside that ink.
will be trapped inside that ink.
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Here, we are talking
about a different space
about a different space
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from the bubbles I'd seen in Paris.
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The bubbles that are trapped
inside those inks
inside those inks
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vary between a few millimeters,
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a few microns
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or even a few nanometers in size.
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And what we are concerned about
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is the oxygen and the moisture
that is trapped inside.
that is trapped inside.
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At this size scale,
removing them is not easy.
removing them is not easy.
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But it matters,
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for instance, for organic
light-emitting diodes inks
light-emitting diodes inks
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that we can use to produce display
for your smartphone, for example.
for your smartphone, for example.
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It's supposed to last for many years,
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but if the ink that we use has been
absorbed with oxygen and moisture
absorbed with oxygen and moisture
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[which] are not being removed,
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then we can quickly see
dark spots appear in the pixels.
dark spots appear in the pixels.
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Now, one challenge we face
in removing the microbubbles
in removing the microbubbles
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is that they are not very cooperative.
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They like to sit there,
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bathing in the ink without moving much.
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But how do we kick them out?
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One technology we use
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is to force the ink going through
a thin, long and tiny tube
a thin, long and tiny tube
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with a porous wall,
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and we place the tubes
inside the vacuum chamber,
inside the vacuum chamber,
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so that the bubbles can be
squeezed out from the ink
squeezed out from the ink
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and be removed.
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Once we manage to remove the bubbles
from the ink that we produce,
from the ink that we produce,
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it is time for celebration.
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Let's open a bubbling champagne.
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Ooh, this is going to be fun!
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(Laughter)
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Woooo!
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(Applause)
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You could see a lot of bubbles
rushing out from the champagne bottle.
rushing out from the champagne bottle.
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These are the bubbles
filled with carbon dioxide,
filled with carbon dioxide,
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a gas that's been produced during
the fermentation process of the wine.
the fermentation process of the wine.
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Let me pour some out.
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I can't miss the chance.
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I guess it's enough.
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(Laughter)
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Here, I can see a lot of microbubbles
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moving from the bottom of the glass
to the top of the champagne.
to the top of the champagne.
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Before it pops,
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it will jet tiny droplets
of aroma molecules
of aroma molecules
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and intensify the flavor of champagne,
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making us enjoy much more
the flavor of champagne.
the flavor of champagne.
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As a scientist who is
passionate about bubbles,
passionate about bubbles,
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I love to see them,
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I love to play with them,
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and I love to study them.
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And also, I love to drink them.
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Thank you.
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(Applause)
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ABOUT THE SPEAKER
Li Wei Tan - Formulation scientistAs a formulation scientist, Li Wei Tan is constantly finding ways to understand why something works and why it doesn't.
Why you should listen
For Li Wei Tan, curiosity is a primary motivation of her work. A senior scientist for Merck KGaA Darmstadt, Germany in Chilworth, United Kingdom, she is responsible for developing ink formulations, new materials and integrations into the company's OPV portfolios, including providing technical advice to new customers. Previously, she worked in Merck's organic electronics R&D group. Her formal studies have straddled fields of nanotechnologies, material science and analytical chemistry.
Li Wei Tan | Speaker | TED.com