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So, I love making tools
and sharing them with people.

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I remember as a child,

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my first tool I built
was actually a microscope

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that I built by stealing lenses
from my brother's eyeglasses.

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He wasn't that thrilled.

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But, you know, maybe
because of that moment,

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30 years later,

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I'm still making microscopes.

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And the reason I built these tools
is for moments like this.

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(Video) Girl: I have
black things in my hair --

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Manu Prakash: This is a school
in the Bay Area.

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(Video) MP: The living world
far supersedes our imagination

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of how things actually work.

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(Video) Boy: Oh my God!

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MP: Right -- oh my God!

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I hadn't realized this would be
such a universal phrase.

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Over the last two years,

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in my lab,

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we built 50,000 Foldscopes

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and shipped them
to 130 countries in the world,

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at no cost to the kids we sent them to.

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This year alone,

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with the support of our community,

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we are planning to ship
a million microscopes

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to kids around the world.

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What does that do?

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It creates an inspiring community
of people around the world,

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learning and teaching each other,

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from Kenya to Kampala
to Kathmandu to Kansas.

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And one of the phenomenal things
that I love about this

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is the sense of community.

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There's a kid in Nicaragua

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teaching others how to identify
mosquito species that carry dengue

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by looking at the larva
under a microscope.

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There's a pharmacologist
who came up with a new way

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to detect fake drugs anywhere.

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There is a girl who wondered:

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"How does glitter actually work?"

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and discovered the physics
of crystalline formation in glitter.

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There is an Argentinian doctor

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who's trying to do field cervical cancer
screening with this tool.

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And yours very truly found
a species of flea

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that was dug inside my heel in my foot
one centimeter deep.

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Now, you might think
of these as anomalies.

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But there is a method to this madness.

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I call this "frugal science" --

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the idea of sharing
the experience of science,

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and not just the information.

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To remind you:

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there are a billion people on this planet

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who live with absolutely
no infrastructure:

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no roads,

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no electricity

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and thus, no health care.

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Also, there a billion kids
on this planet that live in poverty.

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How are we supposed to inspire them

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for the next generation
of solution makers?

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There are health care workers
that we put on the line

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to fight infectious diseases,

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to protect us with absolutely
bare-minimum tools and resources.

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So as a lab at Stanford,

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I think of this from a context
of frugal science

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and building solutions
for these communities.

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Often we think about being able to do
diagnosis under a tree, off-grid.

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I'll tell you two examples
today of new tools.

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One of them starts in Uganda.

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In 2013,

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on a field trip to detect
schistosomiasis with Foldscopes,

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I made a minor observation.

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In a clinic,

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in a far, remote area,

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I saw a centrifuge
being used as a doorstop.

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I mean -- quite literally, the doorstop.

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And I asked them and they said,

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"Oh, we don't actually have electricity,

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so this piece of junk
is good as a doorstop."

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Centrifuges, for some of you
who don't know,

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are the pinnacle tool to be able
to do sample processing.

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You separate components
of blood or body fluids

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to be able to detect
and identify pathogens.

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But centrifuges are bulky, expensive --

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cost around 1,000 dollars --

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and really hard to carry out in the field.

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And of course,

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they don't work without power.

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Sound familiar?

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So we started thinking
about solving this problem,

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and I came back --

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kept thinking about toys.

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Now ...

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I have a few with me here.

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I first started with yo-yos ...

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and I'm a terrible yo-yo thrower.

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Because these objects spin,

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we wondered,

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could we actually use
the physics of these objects

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to be able to build centrifuges?

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This was possibly the worst
throw I could make.

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But you might start realizing,

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if you start exploring
the safe space of toys --

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we tried these spinning tops,

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and then in the lab,

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we stumbled upon this wonder.

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It's the whirligig,
or a buzzer, or a rundle.

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A couple of strings and a little disk,

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and if I push, it spins.

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How many of you have played
with this as a kid?

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This is called a button-on-a-string.

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OK, maybe 50 percent of you.

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What you didn't realize --

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that this little object

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is the oldest toy
in the history of mankind ...

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5,000 years ago.

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We have found relics of this object
hidden around on our planet.

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Now the irony is,

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we actually don't understand
how this little thing works.

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That's when I get excited.

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So we got back to work,

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wrote down a couple of equations.

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If you take the input torque
that you put in,

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you take the drag on this disc,

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and the twist drag on these strings,

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you should be able
to mathematically solve this.

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This is not the only equation in my talk.

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Ten pages of math later,

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we could actually write down
the complete analytical solution

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for this dynamic system.

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And out comes what we call "Paperfuge."

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That's my postdoc Saad Bhamla,

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who's the co-inventor of Paperfuge.

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And to the left, you see
all the centrifuges

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that we're trying to replace.

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This little object that you see right here

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is a disc, a couple
of strings and a handle.

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And when I spin

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and I push,

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it starts to spin.

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Now, when you realize,

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when you do the math,

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when we calculate the rpm for this object,

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mathematically, we should be able
to go all the way to a million rpm.

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Now, there is a little twist
in human anatomy,

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because the resonant frequency
of this object is about 10 hertz,

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and if you've ever played the piano,

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you can't go higher
than two or three hertz.

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The maximum speed we've been able
to achieve with this object

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is not 10,000 rpm,

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not 50,000 rpm --

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120,000 rpm.

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That's equal to 30,000 g-forces.

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If I was to stick you right here
and have it spin,

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you would think about the types
of forces you would experience.

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One of the factors of a tool like this

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is to be able to do diagnosis with this.

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So, I'm going to do
a quick demo here, where --

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this is a moment where I'm going
to make a little finger prick,

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and a tiny drop of blood
is going to come out.

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If you don't like blood,
you don't have to look at it.

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Here is a little lancet.

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These lancets are available everywhere,

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completely passive.

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And if I've had breakfast today ...

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That didn't hurt at all.

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OK, I take a little capillary
with a drop of blood --

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now this drop of blood has answers,

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that's why I'm interested in it.

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It might actually tell me whether
I have malaria right now or not.

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I take a little capillary,

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and you see it starts wicking in.

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I'm going to draw a little more blood.

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And that's good enough for right now.

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Now, I just seal this capillary
by putting it in clay.

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And now that's sealed the sample.

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We're going to take the sample,

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mount it on Paperfuge.

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A little piece of tape
to make a sealed cavity.

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So now the sample is completely enclosed.

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And we are ready for a spin.

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I'm pushing and pulling with this object.

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I'm going to load this up ...

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And you see the object starts spinning.

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Unlike a regular centrifuge,

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this is a counter-rotating centrifuge.

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It goes back and forth, back and forth ...

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And now I'm charging it up,

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and you see it builds momentum.

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And now -- I don't know
if you can hear this --

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30 seconds of this,

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and I should be able to separate
all the blood cells with the plasma.

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And the ratio of those blood 
cells to plasma --

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(Applause)

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Already, if you see right here,

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if you focus on this,

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you should be able to see
a separated volume

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of blood and plasma.

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And the ratio of that actually tells me
whether I might be anemic.

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One the of aspects of this is,
we build many types of Paperfuges.

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This one allows us to identify
malaria parasites

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by running them for a little longer,

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and we can identify malaria parasites
that are in the blood

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that we can separate out and detect
with something like a centrifuge.

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Another version of this allows me
to separate nucleic acids

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to be able to do nucleic acid tests
out in the field itself.

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Here is another version that allows me
to separate bulk samples,

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and then, finally,

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something new that we've been working on

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to be able to implement the entire
multiplex test on an object like this.

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So where you do the sample preparation
and the chemistry in the same object.

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Now ...

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this is all good,

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but when you start thinking about this,

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you have to share these tools with people.

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And one of the things we did is --
we just got back from Madagascar;

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this is what clinical trials
for malaria look like --

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(Laughter)

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You can do this while having coffee.

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But most importantly,

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this is a village six hours from any road.

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We are in a room with one of the senior
members of the community

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and a health care worker.

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It really is this portion of the work
that excites me the most --

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that smile,

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to be able to share simple but powerful
tools with people around the world.

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Now, I forgot to tell you this,

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that all of that cost me 20 cents to make.

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OK, in the negative time I have left,

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I'll tell you about the most recent --

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(Laughter)

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invention from our lab.

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It's called Abuzz --

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the idea that all of you
could help us fight mosquitoes;

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you could all help us track our enemies.

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These are enemies because they cause
malaria, Zika, chikungunya, dengue.

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But the challenge is that we actually
don't know where our enemies are.

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The world map for where
mosquitoes are is missing.

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So we started thinking about this.

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There are 3,500 species of mosquitoes,

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and they're all very similar.

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Some of them are so identical

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that even an entomologist cannot
identify them under a microscope.

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But they have an Achilles' heel.

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This is what mosquitoes flirting
with each other looks like.

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That's a male chasing a female.

244
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They're actually talking to each other
with their wingbeat frequencies.

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(Buzzing sound)

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And thus, they have a signature.

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We realized that using a regular phone,

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a $5-10 flip phone --

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how many remember what this object is?

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(Laughter)

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We can record these acoustic
signatures from mosquitoes.

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I'll tell you exactly how to do this.

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I caught some mosquitoes outside.

254
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Unlike Bill [Gates], I'm not
going to release them.

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(Laughter)

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But I will tell you how
to record from this.

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All you do is tap them and they fly.

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You can first test --

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I can actually hear that.

260
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And you bring your phone,
which has microphones --

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it turns out the mics
are so damn good already,

262
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even on regular phones,

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that you can pick up
this near-field signature.

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And since I'm out of time,

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let me just play the recording
that I made a day ago.

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(Mosquitoes buzz)

267
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This is all the charming sound
that you heard before

268
00:12:15,340 --> 00:12:16,524
that you all love.

269
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One of the contexts of this

270
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is that being able to do this
with a regular cell phone

271
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allows us to map mosquito species.

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Using a flip phone,

273
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we mapped one of the largest
acoustic databases

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00:12:32,375 --> 00:12:37,603
with 25 to 20 species of mosquitoes
that carry human pathogens.

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And from this and machine learning,

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anybody who uploads this data,

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we can identify and tell the probability

278
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of what species of mosquitoes
you're actually working with.

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We call this Abuzz,
and if any of you want to sign up,

280
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just go to the website.

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Let me close with something

282
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that's very important
and dear to my heart.

283
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One of the challenges of today
is we have terrible problems.

284
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We have a billion people
with absolutely no health care,

285
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climate change, biodiversity loss,

286
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on and on and on.

287
00:13:06,226 --> 00:13:09,176
And we hope that science
is going to provide the answer.

288
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But before you leave this theatre today,

289
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I want you to promise one thing.

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We're going to make science accessible --

291
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not just to the people who can afford it,

292
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but a billion others who can't.

293
00:13:21,761 --> 00:13:25,777
Let's make science and scientific
literacy a human right.

294
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The moment that you pass the tingling
feeling of making a discovery

295
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to another child,

296
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you're enabling them to be
the next group of people

297
00:13:38,259 --> 00:13:40,367
who will actually solve these problems.

298
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Thank you.

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(Applause)