You might not think about it very often,
but we are living through a golden age of technology.
Our homes and our pockets are full of inventions and gadgets
that 20 years ago would have been the stuff of science fiction.
Alexa, how exactly do you work?
Hmm, I don't know that. That's what we're going to find out.
These things have become such an integral part of our everyday
lives that we've forgotten to remember how clever they are.
I'm Professor Hannah Fry and I want to open your eyes...
I'm having a great time.
..to the secret genius of everyday objects.
BEEPS
The ones that we take for granted. Items that owe their existence
to generations of scientific innovation.
THE Edison drove an electric car?! Yes, this one.
In every episode, I'm going to take one item...and tear it apart...
GLASS SMASHES
..bit... Ooh!
..by bit... So, now, there's some stuff you can see.
..meet the people behind it...
Frankly, I thought many things were impossible.
..and unlock the remarkable... There is the clandestine listening device.
..and sometimes hilarious stories behind its invention.
Hello! Look at you!
This time...
..it's the fitness tracker. More and more of us
are wearing these devices that are monitoring our every movement,
but these things are also getting increasingly sophisticated.
Three, two, one.
BLAST
So, how did 1970s car crashes help us to count every step?
That would really hurt a lot!
Why did World War II fighter pilots...
I mean, I know what you're thinking. Tom Cruise, right?
..lead to miniature health monitors?
Rick Dabate now guilty on all three counts.
And how did we get from our tracking our movement to tracking killers?
They'd planned to use Connie's Fitbit as evidence.
Tracking our every step, jump or hop is more popular than ever,
with around a third of the UK population now owning
a fitness tracker.
I'm in Silicon Valley to meet one of the innovators behind iconic
fitness tracker company Fitbit.
But first... Hmm, I've got a confession to make.
The team at Fitbit have let me borrow one of their devices
while we're filming the show.
I'm still trying to work out how it works.
I used to have one of these, but I kind of gave it up.
I know they're supposed to encourage you to do more exercise,
but I actually found it mostly made me
feel guilty for when I was being lazy.
But maybe this time's going to be different.
Fitbit were one of the very first fitness tracker companies
and have sold millions of devices worldwide,
so if anyone can help me find the genius of the tracker, and maybe
help me work out how to use their own, it's one of their pioneers.
So, you're one of the original Fitbit-ers? Yeah, sort of. Yeah.
Go on, tell me...
That's Shelten Yuen, Fitbit's principal scientist.
Tell me the story about how you joined.
So, I was doing research in surgical robotics
and trying to do beating-heart surgery
and the two co-founders of Fitbit came up to me with this
idea - could we put motion sensors on people,
help them track their health, and then get them to be healthier?
And I was like, you know, "When you're working on someone's heart,
"it's usually pretty late in the game and what
"if you could actually help them way before that, 20 years before that?" And I was like, "Sign me up."
And there was one crucial component that made the Fitbit origin
story possible. It was right at the cusp
when accelerometers were getting quite small and they were
actually getting to the order of, like, millimetres in size.
Wait, what was that? Right at the cusp when accelerometers...
That's it, the accelerometer.
It's the thing that measures your movement.
Let's introduce it again with a graphic.
The fitness tracker is a miracle of miniaturisation.
I'm going to take it apart and look at five key components,
from the heart rate monitor to the memory card.
But I'm starting with the super-sensitive motion sensor
that picks up your every move,
the accelerometer.
So, I've got this fancy device that the kind people of Fitbit
have given me. What am I going to do with it?
I'm going to tear it to pieces, of course.
I'm borrowing someone's garage and I'm going to need some tools.
This could be brutal!
So...
..let's get this guy down.
If you value your Fitbit, I wouldn't recommend doing this.
But the screen on top is glued on, so I'm going to melt the glue,
using a 400-degree heat gun.
Getting to the accelerometer inside here isn't easy.
This screen is made of secured toughened glass. Ooh! Sticky!
FITBIT BEEPS
OK... We're open.
Ooh! Teeny-tiny screws.
I'm having a great time.
Now, I think I've got a good chance of getting the motherboard out now.
There it is. Oh, wow!
Battery.
So, now, there's some stuff you can see.
This is where everything happens.
This tiny little circuit.
On this circuit board, in a tiny two-millimetre square,
is the revolutionary sensor that helps track your every move.
This miniature little square - that is the accelerometer.
This is the motion sensor that counts our steps
and figures out how our body is moving,
in any direction.
What's going on in here, essentially,
is imagine that you've got two combs.
One of them is kind of rigid, the motherboard,
and the other one is free to move. But they're interlocked together.
So as you move up and down in that axis, this one sort of bends
and stretches around the other.
As the distance between the combs changes, an electrical signal
is sent to the device, telling it that you're moving.
But a single pair of combs can only detect movement in one direction.
That is why an accelerometer needs multiple pairs,
so it can work out what's going on in all three dimensions.
It's not just up and down.
It's up, down, forward, back, left, right, all at the same time.
But that, essentially, this mechanical device,
embedded in an electrical circuit, is the thing that allows you
to calculate how many steps you're doing.
The accelerometer is an ingenious device, but to find out how we
got here, first we need to go back to Renaissance Italy.
It's the early 16th century and the Papal Army want more-accurate maps.
So, they hire a talented engineer by the name of Leo.
Or Leonardo da Vinci, to you and me.
He realises that if you can work out the number of steps that
soldiers are taking, it will give him
a pretty accurate indication of distances for the maps.
So, he invents an elaborate gear-driven contraption
worn at the waist.
It has a long pendulum tied to the thigh, sounds comfy,
and as you walk, the gears rotate and, voila, steps are counted.
It's thought to be one of the earliest examples of what
we now call a pedometer. For centuries,
pedometers like Leonardo's remained the best way to count steps.
They got smaller and more wearable,
but were still clunky and not very accurate.
The big development that would take us
to today's accelerometer was an absolute car crash.
Safety that evolves from a continuing programme of crashing
test vehicles.
It was all thanks to the airbag.
After the end of the Second World War, 1950s,
people started buying cars in their thousands.
The only problem was, at the time, cars were a complete deathtrap,
so manufacturers start introducing safety measures like seat belts,
but surprise-surprise, nobody wants to wear them.
And so, that is the environment in which the airbag was invented.
A typical crash is over in 100 milliseconds, a tenth of a second.
That is Matthew Avery. Here at Thatcham Research,
he crashes cars for a living.
And he's kindly agreed to let me watch.
Is there anyone down there? No. No, everything's clear.
The doors are locked. OK.
A specially built sled is going to replicate
the force of a head-on collision, with this poor sucker at the wheel.
So, it's like a giant air rifle, this thing? Pretty much, yeah.
Five, four, three, two, one.
Ah, hold it there! Before we see it in action,
you might be wondering what all this has got to do with fitness trackers.
What is it that sets off an airbag in a car?
It's an accelerometer, like these.
Our old friend, the accelerometer.
But back in the days of early airbags,
they weren't quite the miniature marvels of engineering...
Ooh! ..that we know today.
The early accelerometers were just a sprung mass with like a ball
bearing in, and basically, they're a contact centre,
so when you apply enough force on it,
it will create a switch which could deploy an airbag, for example.
Here is a crash into a barrier.
The ball bearing was held by a magnet.
If the car suddenly decelerated,
the ball would release from the magnet, roll down a tube
and close an electrical circuit, triggering the airbag.
They're contained in a sort of box like this,
so here's an earlier airbag controller module.
Yeah, that's... That's not going to fit in my Fitbit.
You can see how big and chunky.
And because these first accelerometers were so basic,
they were prone to unexpectedly trigger with any sudden jolt,
like a bump, or a kerb, or a pothole.
Did that used to happen all the time? Did airbags just go off?
The early airbags, maybe from the 1970s,
which had much cruder accelerometers on, that could happen, yes.
The need for less trigger-happy airbags led to an intense
period of research.
Until airbags are standard equipment on the American highway,
tens of thousands of us will die.
Airbag engineers utilised a new microchip technology called
MEMS, which let them carve moving parts directly onto tiny
circuits and the result was smaller, more precise accelerometers.
And now, they're a lot more sophisticated
and that level of sophistication means they can discern
the difference between hitting the kerb and hitting another vehicle.
The evolution from this simple giant chunky thing down to on this
board and a recognisable little tiny accelerometer.
It's kind of cool, isn't it? That's it.
OK. Well, let's see today's airbag accelerometer in action.
Five, four, three, two, one.
BLAST
Wow! Yeah.
Pretty severe impact. That would really hurt a lot! Absolutely, yeah.
I didn't even really see the airbag.
Luckily, we can watch again in slow-mo.
Within 20 milliseconds, the airbag has deployed
and protecting the occupant, and that's what those accelerometers
are doing, measuring that force and saying this is a severe
collision, I need to deploy to protect the occupant.
In just a 50th of a second,
the accelerometer has precisely measured the acceleration,
allowing its control unit to calculate the moment that the
airbag should activate and it's that same incredible precision
that tells my fitness tracker how I'm moving through space.
The development of crash testing and airbags has really pushed
forward the sophistication of the accelerometer and played a huge
part in the miniaturisation and the proliferation of accelerometers.
Do you know? It's really lovely when you get something that is so tiny,
that has saved so many people's lives.
That's right, yeah. Cars are now much safer than they ever have been.
The accelerometers developed for airbags were
so good at measuring precise changes in speed and direction
that they quickly found a home in other...essential devices,
like video game controllers.
And there, they caught the eye of a certain Silicon Valley entrepreneur.
Back to Shelten.
And I was actually part of the origin story of Fitbit.
James, one of our co-founders, was standing in line,
waiting for a Wii...
That's a Nintendo Wii, not the men's room.
..and he was like, "Hey, I can have fun doing exercise with this thing.
"What if I could take that idea and put it out into the real world,
"where people are moving around in their daily lives?" We settled on this idea that
if we could track people's steps and just give them a sense of their overall activity,
that would be a huge lift above what you could do back then.
The prototype Fitbit was attached to the hip,
just like Leonardo's pedometer,
making step counting easy because the hip just slides forward
and back as you walk.
But the Fitbit founders had other ideas.
They wanted their new tracking device to go onto the waviest
part of your body.
Did you try and persuade them to not make it a wrist device? Yes. I did!
Really? Yes, I did.
Yeah, the co-founders were like, "The future's the wrist.
"We have to make this work on the wrist," and I was like, "Are you sure about that?"
And presumably, people don't always swing their arms in the same way, either. Oh, no.
It suddenly went from you describing it as what
seemed like a relatively straightforward problem to
something that, like, frankly seems impossible.
Were there any points like at two o'clock in the morning
when you woke up and were like, "I just don't think we can do it"?
Yeah, frankly, I thought many things were impossible. The accelerometer gave them
precise details of how the tracker was moving, but then,
Shelten had to figure out which wrist movements were actually steps.
What do you expect to see when someone takes a step?
Well, I actually have some data that we could look at, if you like. OK. Amazing. Yes. Always.
These downward peaks here is a step. OK.
So, in orange there, that's the one that's essentially up, down axis.
Is that right? Yeah, in the opposite direction of gravity. Sure.
And then, there, these peaks, they've actually got quite a
nice pattern to them, so, like, it's like the second one is a bit spiky.
Yeah. And then, you have these like nice dips in between.
So, that actually looks really clear.
One distinct move of the wrist equals one step.
But what if you're not marching like a soldier
and you start waving your hands around instead?
So I would contend that this person is probably walking at a pretty good
clip and maybe they decided to like, I don't know,
scratch their shoulder or something while they're doing it. But then, how are you supposed to find
the signal in there of the walk, if the thing that they're doing with
their arms, scratching their head, or whatever, is the dominant signal.
So it is a little bit tricky and so... A little bit tricky.
So we do a lot of signal processing filtering and machine learning
to try to figure out what's noise and what's actual user activity.
The accelerometer detects the movement in three dimensions
and then, quite clever algorithms based on billions of data points
will work out which combinations of movement are actually steps.
I'm genuinely amazed that you've managed to solve this
problem at all. How long did it take you, from beginning to end?
I mean, it was... It's been 15 years.
I think we're still on the journey.
The very first algorithm was not nearly as complicated as we're
talking about today, but today, you know, we have access to labs,
gyms, where we can collect much more data and turn a lot of machine
learning techniques, AI techniques, to the problem.
And so, that is the story of how we got an accelerometer
sensitive enough to track our every step and clever enough to know
when you're just doing the Macarena.
But today's trackers do far more than just count steps...
..monitoring everything from sleep to stress levels,
to assess our health.
Our next component is the most important health sensor of all.
It uses the power of light to track the beats of the body's most
critical organ. This is the heart rate sensor.
50 years ago, if you wanted to find out about your own physiology,
you would have had to have gone to a specialist lab,
wire yourself up to all sorts of equipment.
Now, they can pretty much do all of that for you.
I'm back with the lovely Shelten,
who seems determined to make me do a workout.
It might be good to actually check your heart rate right now.
It's the green light at the back of the fitness tracker that's
key to the heart rate sensor.
So, why green light?
So it has to do sort of with how light travels through tissue, so
green light happens to go through a good layer of tissue where
there's a capillary bed and that capillary bed is pulsating,
basically because your heart is beating.
Or another way to put that, you're seeing through the skin.
And the capillaries that are just underneath those top layers of
skin, they're sort of swelling and contracting, as blood goes through.
That's correct, yeah. That's exactly it.
Measuring heart rate using light is called photoplethysmography
and luckily, it's easier to explain than it is to pronounce.
As the blood vessels expand and contract, they are filled with more
or less blood, meaning they absorb more or less of the green light.
The rhythm of those changes is what gives our heart rate.
I mean, you must be talking about tiny, tiny measurements here. Yeah, they're really small.
There's a lot of algorithms that really have to look into that signal to try to extract your heart
rate from it, particularly when you're moving.
Yeah. It's tricky. Yeah!
What's even trickier is that the light is a huge drain in the battery
and that's not great for a device that's designed to be worn 24/7.
The batteries in these devices are probably, I don't know,
15 times smaller than what's in a phone and so, you're really
thinking about - how do you economise your use of these lights?
Is that the reason why they're flashing, rather than just a constant light? Yeah. Oh, really?
To test out this tiny device on my wrist, I am comparing it...
And already, I can see it's gone up to 108.
..to this very expensive hospital-grade
electrocardiogram, or ECG.
Instead of light, the ECG uses electrodes attached to my body
and it gives a far more detailed reading,
but it is pretty cumbersome.
OK, so how are the two comparing? 106.
102? Ah, there's a delay. 107, 108. It's a little bit behind.
Got you. Wow, it's got to do all that number crunching.
The performance is impressive,
especially on something that you can take anywhere.
But how in the world did we manage to shrink down functions
of an ECG machine, so that it could fit on our wrist?
The answer can be traced back to the ski trails of Finland in the 1970s.
Just a warning,
the following footage contains some serious 1970s shell suits.
One snowy day,
the coach of a Finnish cross-country ski team bumped into his friend,
a professor of medicine, whose name is even harder to pronounce
than photoplethysmography.
They discussed how they could monitor skiers'
performance more accurately, even in the cold, dark forests -
if they could measure their heart rates during training, not after.
And so, the professor set about inventing the very first
portable battery-operated heart rate monitor.
It consisted of a radio-equipped strap, worn around the chest
and a wristwatch that displayed the data,
like a portable version of the ECG electrodes.
It helped the Finns to up their game
and was the first step towards today's heart rate monitors.
But to ditch the chest strap completely,
that took the development of, well, you guessed it,
the green light photoplethysmography in 2004.
The heart rate sensor was one of the first medical devices to
go into our trackers.
But our next component is a sophisticated recent addition.
It uses red and infrared light to measure the oxygen
levels in your blood.
This is the blood oxygen monitor.
OK, so these things... I think everyone recognises
what these are now... Yeah. ..after Covid.
These are the things that measure the oxygen levels in your blood,
aren't they? Right. But you can do that in here as well?
Yeah, so the optical sensor that's in the watch right now,
you can see the green. Now, there's actually a red and infrared sensor in it as well.
OK. And infrared, you can't see by eye.
So when you're quite still, what it can do is
look for your SpO2 or oxygen saturation that's in your blood.
Oh, that's interesting!
Blood oxygen levels should be high, if you're healthy,
and so monitoring changes can alert you to everything from
Covid-19 to a potentially dangerous condition called sleep apnoea.
But to find the origins of portable blood oxygen monitors, we have to
go back to the frenzied air battles of World War II fighter pilots.
They didn't have long to wait. As the war began,
Allied Forces took to the air in order to protect the skies.
Flying by the seat of their pants, thousands of new pilots
pushed their cutting-edge planes to the limit in sky-high dogfights.
The National Museum of World War II Aviation in Colorado Springs
holds some of the best examples of aircraft from that time.
It's the 1940s, fighter pilots are going up in absolutely
beautiful aircraft like this.
This is the Brewster F3A Corsair and it's very lightweight,
absolutely perfect for air-to-air combat, or dogfights, to you and me.
They're not that easy to get into. Let's see how I do.
Because they were urgently needed,
young fighter pilots had to be trained in a matter of months.
Holy Moley! This is absolutely extraordinary.
And there's a foot hole here somewhere. There?
SHE LAUGHS
I think I'm stuck!
I mean, I know what you're thinking. Tom Cruise, right?
How... How... How they did this?!
The real pilots were clearly as agile as their planes.
But the new planes introduced new problems. They flew much higher and
flying at high altitude could be fatal.
So, as well as flying what is essentially a glorified tin can,
the cabins on these things weren't pressurised, so the pilots
would wear these oxygen masks, and there's a little tank down here.
If they didn't give themselves enough oxygen,
they would black out, which is definitely not ideal.
Yes, I'm all right.
At that time, the only way to monitor blood oxygen levels
was in a hospital.
And so, a solution was desperately needed.
The Royal Air Force in Britain, they wanted a way to monitor
a pilot's oxygen levels before they lost consciousness.
So, they enlisted the help of an American physiologist called
Glenn Millikan.
Millikan was a keen mountaineer,
which would have been great news to his father-in-law, because
he married the daughter of famed Everest climber George Mallory.
Now, Millikan, he knew that a lack of oxygen at high altitude
was a problem, and he'd already been experimenting with
lots of different ways to try and measure oxygen levels in the blood.
Now, we've known quite a lot about how the blood carries oxygen, since the 1800s.
That was when haemoglobin was discovered, that's the protein
that carried oxygen, it's the thing that makes your blood red.
And the amount of oxygen in your blood changes the colour of it,
so if you have got really oxygen-rich blood, it's a very
bright colour, but as the oxygen depletes,
it ends up becoming a much darker, deeper shade of red.
Millikan's breakthrough came form understanding that machines
could measure blood oxygen levels by simply looking at how
dark the blood vessels were.
So, he created a very clever little device,
a little bit like this, I borrowed this one from the museum.
This is called an ear oximeter.
A little device that clips onto your ear.
And what happens is that there's a little light that comes out of one
side of it and a sensor on the other side,
so hang on, let me try and put it on. You go like this...
Pop it on your ear.
As it clamps onto your ear, it shines through a red light
and an infrared light, which heats up that little bit of skin
and dilates all of your blood vessels,
creating a little pool of blood.
And then, a sensor on the other side can detect how
much of the light is passing through and tell how dark your blood is,
or equivalently, how much oxygen you have in your system.
Millikan's device was fitted to the pilot's mask
and it would control the flow of oxygen needed.
Apparently, Millikan would demonstrate this
device by clipping it onto his ear
and his wife said he would hold his breath
until he was blue in the face and then, after a short delay,
the drop in oxygen levels would be registered by the device.
And this became known as the Millikan's oximeter.
After the War, cabin pressure systems became widespread,
allowing normal breathing at high altitude.
But portable oximeters didn't become redundant.
Instead, they were adapted from the ear to the finger
and became the portable pulse oximeters that we know today.
By now, these oximeters are such a crucial medical device that
it's easy to forget that it had its origins in the military,
a time when there was a real sense of urgency
and when the stakes couldn't have been higher.
Sadly, Millikan died in 1947 in a mountaineering accident
and so never got to see how his technology revolutionised medicine.
But his legacy lives on, not only in hospitals,
but also miniaturised, right down into our fitness trackers.
With more delicate electronics than you can shake a USB stick at,
fitness trackers have to withstand all of the knocks
and the bumps that we invariably put them through.
So I heard this great story about a pig that was wearing a fitness
tracker, monitoring its step count and proving that it was free-range.
Except, unfortunately, one day, the fitness tracker fell off,
the pig eats it, it got damaged in the digestive tract,
ended up causing a fire when it came out the other end.
Now, that is quite an extreme thing for a fitness
tracker to have to go through. SNORTS
But when you're building this stuff, you certainly don't want to create
one that's just going to fall apart at the slightest knock or scrape.
And that is why those clever fitness tracker designers have added
a component that makes them
robust enough to withstand almost anything that we throw at them -
the toughened-glass screen.
But just how strong is the glass?
Well, this is the place that the tech companies come to to find out.
If you really want to test something,
give it to a four-year-old.
That is Terry Liu from Quanta Laboratories.
His job is to try and break stuff,
testing-out products for most of the major companies...
Oh!
..in Silicon Valley.
Do you ever just want to, like, smash stuff?
That's what we do. I know!.
Terry puts products through their paces to make sure
that they can withstand whatever we do to them.
Although, OK, maybe not the pig thing.
This is what we call the Guided Drop.
And, basically, it drops a unit in any direction and point.
It basically holds on to it and at the last foot,
it lets it go, and drops it and hits the perfect flat drop.
To test just how much stress the glass can withstand,
Terry has a machine that will drop the device from various heights.
We're starting at eight feet.
Oh, my gosh.
You want to go higher?
Nothing.
15 feet. Wow.
The glass is proving tricky to damage by dropping,
but how about resisting scratches from keys
in our pockets, for example?
Well, Terry has a whole other machine for testing just that.
This test right now can add different weights on there.
How much weight to put on it,
how much force and pressure to put on it.
So there's a certain amount of weight that presumably
the manufacturers say that's OK. Yeah.
So we can see no real scratch marks. Nothing.
Just going back and forth.
Can you put it in your pocket? Of course.
Would I recommend that? Probably not.
I wouldn't put my watch in my pocket if I know I had keys there.
I had one of these smartwatches,
and my daughter was having a tantrum in a supermarket... Sure.
And like a fool, to try and get her out of her tantrum,
I said she could wear my smartwatch, at which point she proceeded
to have this huge tantrum on the floor.
And then by the end, I mean, it was so scratched
you could barely see it. They just know how.
We actually tested a bunch of these toys and it was just crazy,
the types of tests we have to do on them.
All the bodily fluids you have to try on it, it's just nasty.
Fake sweat, fake pee.
We have different acids that you can put on there.
And this is what I think about all day.
How do I torture a device?
Well, my old smartwatch died back in the cereal aisle
of the supermarket. RIP.
But this one has survived a 15-foot fall
and Terry's scratch test.
It's the Bruce Willis of smartwatches.
So far, we've dropped the device onto wood,
but now it's time for the toughest test so far.
We could do a concrete drop.
You want concrete? Yes.
Oh, that did not sound good.
There's one little crack. There's one little crack?
I'm sure the next one would do it. A teeny, tiny hairline.
Astonishingly, the glass only has a small crack.
Go on, let's smash it again, smash it again. Sure.
Wow, that sounded pretty good.
It's a little disappointing that we can't break it that easily, huh?
One more to put it out of its misery?
Obviously!
Sod your four-year-olds. I think I want to come and work for you.
Yes, no problem.
OK, so that glass screen did do pretty well,
but most normal glass couldn't have taken that pounding.
And here is why.
These two panes of glass, one over here, one over there.
They look quite similar, don't they? But watch what happens...
..after I very slowly get these gloves on.
Oh! This is ordinary glass. Very, very brittle.
Compare that now to this glass over here,
this is toughened glass.
That's barely left a mark on it.
If I really gave it some wellie, I could smash it, but there's
definitely a difference between these two panes of glass.
The secret is chemistry.
But first, I just need to undo this.
Oh!
Going to go into a little bit about the molecular structure of glass.
But just bear with me because, I promise,
this is going to be worth it.
Glass is actually a supercooled liquid,
so you can think of it more like some strings of beads of atoms
rather than like a really nice regular structure.
And glass, it's made from sand, limestone and sodium.
Charged particles, or ions, of the sodium will sit inside
this structure. Just on the surface like that.
Right, that's normal glass.
Now, when it comes to toughened glass, you have the same sort
of strings that kind of go like this,
but instead, they deliberately remove sodium ions on the surface
and replace them instead with potassium.
Don't know if you remember any of your chemistry from school,
but potassium is a much bigger ion than sodium.
And, so, its presence in this structure...
..means that those strings of beads fill up,
the spaces between these strings
are like squished out towards the edges.
And it means that if ever something comes along...
..and cracks...
..down here, the potassium helps to just keep everything
neatly knitted together.
But the story of how we got toughened glass,
that starts with a mistake.
It's 1953, and in the small town of Corning, USA,
chemist Donald Stookey accidentally cooks a batch of glass
at 900 degrees instead of 600.
Expecting a molten mess, he pulls the glass from the furnace,
but the tongs slip and it crashes to the floor,
where, instead of shattering, it bounces.
Stookey has invented a super-strong glass ceramic,
which becomes used in everything from ballistic missiles...
From rocket research, a great new cook and serve wear,
made of an amazing new material that defies heat and cold.
..to heatproof cookware.
It can stand empty over hot flames,
then go sizzling hot into ice water without damage.
The success kick-starts a flurry of research into toughened glass,
called Project Muscle.
Half a century later, some guy called Steve comes looking for
an ultra-durable glass for his new product.
The story goes that he shook the toughened glass in a bag of keys,
and it came out without a scratch.
That man was Steve Jobs, and around six months later...
It's a breakthrough phone.
..Apple releases the original iPhone with a revolutionary glass screen.
Now known as Gorilla Glass,
it's probably in many of the electronic devices you own.
You really want to see it smashed, don't you? Because I do.
Hold on. Let's give it some welly.
Woo!
I mean, it's definitely not indestructible, is it?
There is one more crucial part to our fitness tracker.
It's where all that information on our health and activity,
or inactivity, is stored.
Now, what was it called again?
Ah, yes, the memory card.
If I flick through this thing,
it can tell me all sorts of data about myself.
It tells me how many steps I've done, how far I've walked.
You can even track your sleep and heart rate.
All of that data is stored on a little memory card
hidden inside the Fitbit, which just so happens to be sitting here
on a canal-side bench in London.
You can see just there, it's got 4G on the end, which is four gigabytes,
and that's the size of this memory card.
Now, you might imagine that that's quite generous, but if you think
about the amount of information that this thing is collecting...
..actually, this memory card gets filled up within about a week,
at which point it needs to sync to the cloud via Bluetooth.
There it joins the data from every other Fitbit,
all stored on a network of servers across the world.
And today, the medical profession is realising the potential value
of this massive health data set.
There is this new initiative where you can share data
from your fitness tracker with doctors.
But remember that if this is the data for you as an individual,
from the perspective of a Fitbit, they have the data not just for you,
but for millions and millions of people simultaneously,
which allows them to search for patterns in the way
that we are all really behaving
that might help us understand medical issues
better and sooner.
Collecting the health data of entire populations might sound
like an episode of Black Mirror,
but in fact it has its origins in the 17th century.
It's the 1660s,
and Britain is reeling after 20 years of bloody civil war.
A London haberdasher called John Graunt takes up a macabre hobby,
studying mortality rates,
and the result is the first-ever collection of public health data.
His extraordinary findings include the urban penalty effect, proof
that moving from the countryside to the city is bad for your health.
Within five years, two of the worst public health crises of all time -
the bubonic plague and the Great Fire -
both hit London, making Graunt's data collection techniques
invaluable and giving him the title
of the founding father of epidemiology.
300 years later, British doctors Richard Doll and Tony Hill
took public health data one step further,
not just collecting the data, but also analysing it
to find the cause of a killer disease.
There had been unexplained increases in lung cancer deaths in men.
Common explanations were coal fires,
car exhausts or tarring on the roads.
But Richard and Tony studied 1,400 patients across London,
asking them detailed questions about their lives
and painstakingly cross-referencing the answers by hand.
They found another cause altogether...
Have you tried to give it up? I have, yes, a couple of times.
..smoking.
I don't think it, I don't think it makes any difference at all.
Hmm, don't be so sure about that, mate.
It was a turning point in finding the link between supposedly harmless
cigarettes and lung cancer.
Do you intend to do anything about it now?
No, I don't. Still carry on.
We've travelled a long way from 17th-century ledgers,
and today the Fitbit is also helping to shape public health.
I'm not even allowed to be in the centre of the table.
This is all you. Light's on you, camera's on you.
That is Dr Tony Faranesh, Fitbit's lead research scientist.
In 2020, he ran a trial to see if big data could help identify
a heart condition called atrial fibrillation, or AFib.
So we invited all of our user base in the US, age 22 and older,
to participate, and over 455,000 people enrolled.
AFib is a potentially fatal condition
where the heart beats fast and erratically.
So if we look here, this is a typical electrocardiogram
of someone with normal rhythm, where the beats are very regular.
So this is like the traditional way of measuring it.
This is somebody with loads of things stuck to their chest.
That's right. A normal person, you can see that there's some variation,
and with AFib you can see that the distance changes.
It's all over the place. It's all over the place.
It's close together, far, close together, far,
without any sort of discernible pattern.
And that's the hallmark of AFib.
That's jazz for the heart.
That's your heart doing a little bit of a jazz number. Yeah.
How common is this condition? Yeah.
Rough numbers, at least in the US, it's estimated that if you're 65
and older, there's around 10% of the people have atrial fibrillation.
10%? 10%.
And if you're younger than 65, that number is closer to 1% or 2%.
AFib symptoms come and go,
so it is easily missed by a one-off appointment with a doctor.
But many fitness trackers now monitor our heart continuously,
so Tony and his team were in the perfect position
to detect AFib early.
And the results are in - normal sinus rhythm.
No signs of atrial fibrillation. That's correct.
OK. This is good. This is good news.
How accurate does it end up being? Ends up being very accurate.
The results from nearly half a million people's trackers
were astonishing.
They found 4,500 people
who may have had AFib without even knowing it.
Our main goal is identify those people who are at highest risk
of this condition, to follow up with their clinician to get
a confirmatory diagnosis. Got you.
The study was so successful that in April 2022,
the FDA certified the device as an accurate method
of detecting atrial fibrillation.
Solving health problems is what fitness trackers were designed for.
But what's more surprising is that they're now
also solving crimes.
In 2016, the data from one tracker hit headlines around the world.
39-year-old Connie Dabate was found dead just before Christmas.
Police responded to her Birchview Drive home after the house alarm
was activated.
On the 23rd of December 2015,
Connie Dabate was shot dead at her home in Ellington, Connecticut.
The more time passes without answers,
the more the rumour mill seems to churn.
They found her husband, Richard Dabate, injured
inside the smoky home.
16 months later, Connie's husband, Richard,
was charged with her murder.
One man was present at the trial day in, day out.
The Dabate trial, Richard Dabate,
was by far the biggest case that I've covered.
That is Matthew Knox, a local newspaper reporter
who had a front-row seat as the trial unfolded.
The case centred on Richard Dabate's claim that his wife was murdered
by an intruder.
A murder trial against a man from Ellington
accused of killing his wife back in 2015, finally got started today
after several delays.
The prosecution gathered data from the house alarm system,
GPS tracking on Richard Dabate's phone and, crucially,
from Connie's fitness tracker.
The trial became known as the Fitbit Murder Case.
As the state continues to make its case,
they plan to use Connie's Fitbit as evidence.
Connie's fitness tracker recorded her movements that morning,
and when they stopped.
According to Richard Dabate's original statement,
Connie would have been killed likely around 9:30 am.
But her fitness tracker showed that she spent
the next 40 minutes moving.
There was movement up until a final movement at 10:05.
The defence attorney tried his best to discredit the tracker evidence.
He pointed out to the jury, it's a device that's made
by a company for profit,
for people to use so they can track how many steps they took that day.
It wasn't created to help solve crimes.
But the prosecution, in turn, called an expert witness
who had carried out a study showing the tracker had 98% accuracy.
After a five-week trial, the jurors were sent out to decide
on a verdict.
Jury deliberations set to continue tomorrow.
We are on verdict watch here.
You could tell in the courtroom that there was a lot of...
..you know, tension.
A jury finding Rick Dabate guilty
in the killing of his wife, Connie Dabate.
It was clear that the fitness-tracker evidence
had been compelling.
It finished out the puzzle,
knowing she's moving around, knowing that she's alive
and then, and then she stops moving.
That's the moment that she was killed.
It emerged that Richard Dabate had been having an affair
and the woman had fallen pregnant.
It seemed he killed his wife to avoid the fallout of a divorce.
In August 2022, he was sentenced to 65 years in prison.
The use of the fitness tracking data was new,
though we'll see if it gets used more often in the future.
Used for good, there is no doubt that big data can have benefits.
But there can also be downsides.
Data is a commodity, a potentially very lucrative one.
So wherever there's personal data being collected, you have to ask
the question - who's accessing it and who's benefiting?
Imagine that one day your boss gives you one of these devices.
You're very excited. You're walking around your neighbourhood,
you're running around counting your steps. It's all very thrilling.
But then after a while, you stop doing quite so much activity.
Maybe you've got a bit of a dodgy leg,
maybe you've got a newborn baby at home.
For whatever reason, your activity levels drop
and it's all fine until you get a letter through
saying that your insurance premiums are going up,
and you realise that it's all connected.
The data from your device saying that you're not being active enough.
Now, that might sound like a dystopian tale from the future,
except that this is something that is already happening.
It's becoming more popular for large companies to hand out
fitness trackers to their employees.
The idea is seen as a win-win.
It will help improve employees' health and therefore make them
more productive.
But there are other factors at play here, and some companies,
like BP in the US, have tied the health data from their employees'
trackers to insurance premiums.
Tesco are said to have given some employees armbands which collect
data on their movement and monitor breaks.
While Hitachi have created ID badges that record when employees meet
each other and how they behave in meetings.
It's worth remembering that a lot of the time you can still decide
not to accept a fitness tracker from your employer.
There are a few things that you can do to protect your privacy
when it comes to this data collection.
The first and most important thing you can do is to actually go
through the privacy policy, because there will often be things
in there that you can opt in or out of.
You can also just hide your real identity,
just don't tell them your real name,
but you can put limits on the amount of data that is collected.
And a generally quite good thing to do is to go through regularly
and just delete any data that you don't have any use for.
It's kind of unfortunate that we live in a world
where the onus is on you, the individual,
to protect your own privacy.
From their tiny sensors to the powerful data that they collect,
fitness trackers look like they're here to stay.
And yet, soon, we might be able to monitor our movement
without traditional trackers at all.
I'm about to show you something that will knock your socks off.
Hah! Just been for a gentle run
and I'm not wearing any kind of wrist tracker,
and yet I've been able to collect all kinds of data about how fast
I was going, about how many steps I was doing, and lots more besides.
That is because I'm wearing smart socks.
Not smart as in, you wear them with a suit,
but smart, as in they can track your movements.
The sock is actually not a traditional sock,
but it's more like a computer.
That is Maurizio Macagno,
CTO of Seattle tech company, Sensoria
who have developed this most unusual footwear.
Tell me how the sock works, then.
So the sock is injected with the sensors.
You have pressure sensors on the plantar area, three of them,
one on the heel and two on the metatarsal bones.
So I guess if you've got, if you've got a sensor at the back
and sensors at the front, you can then tell how your foot
is striking the ground. Exactly Where are you landing first.
And whether it's rolling. But in terms of the information
that you're getting out of these, is it substantially different
to what you would get if you were wearing a wrist monitor?
Totally, because you actually get data directly at the foot level.
Right, time to put this to the test.
I'm going to need to dock this sock.
It collects data from the sensors, which will be sent via Bluetooth
to an app on my phone.
So now I am ready to set off
for an even more gentle run around the park.
So how was it?
OK. It was good. 21 calories?!
So can I have a look at my data from our run? Yes.
Here you see the very high-level data.
So you have cadence. You run a 156 cadence average. Sure.
So if we go here, you can see the sections of the run
when you were heel striking versus ball striking.
I'm nothing if not inconsistent.
The important thing is that you trend towards what you want to do.
The ability to measure your technique precisely is very clever.
But look, you've just seen my run.
Are these socks really going to have an appeal for anyone
other than super-keen athletes?
It turns out Maurizio has a vision for these socks beyond fitness.
Imagine this, that can actually help a person heal better.
His idea is to try and help people with neurological diseases,
like Parkinson's or multiple sclerosis,
monitoring how they're walking and alerting their doctor
if there is a problem.
So we give information that is not diagnostic per se,
but gives a lot of insights to the doctor to make at least an alert
and maybe help them sooner than later.
That sounds promising,
but I have a nagging worry about this concept.
How quickly do these become really smelly?
You can wash the socks. Yeah, absolutely.
And that's been one hell of a journey for us as a company.
This is a computer in the end, so you're washing a computer.
So we have to provide proper waterproofing.
But you can definitely wash them.
But this tech doesn't come cheap.
£340 a pair, to be precise.
Ouch.
I think that might be more than my washing machine.
But it does make me wonder where all this is heading.
Let's check back in with Shelten.
Presumably, there's a limit to what you can ever record from the wrist.
So does that mean that we can expect devices that are much more wearable?
I don't know, like, sort of health-tracking leggings
or like health-tracking, I don't know, bodysuits?
I think there's a potential for that.
But as a thought experiment, one would have to sort of figure out
the power problem. No-one wants to charge their shirt, right?
No-one wants to charge their underwear or something, right?
And you have to really kind of figure out how to make that type
of stuff very usable.
It's like the new, "Sorry, I can't come out, I'm washing my hair.
"Sorry, I can't come out, I'm charging my underpants!"
Right! Right!
In addition to the socks,
all kinds of smart clothes are in development.
Smart yoga pants that will help you to find the right pose
and jackets that will give you directions.
Who knows? Maybe one day there will be a whole outfit
that can just go to the gym for you.
Let's say that we were having this conversation in, I don't know,
20 or 30 years' time, do we expect that there will be devices
that will be continually monitoring the full health of your body
and alerting you to whenever something looks like it's going
in the wrong direction?
That's my hope.
I think the idea that we can act as a safety net, this technology
can really catch you before you, before you get really sick
and have to go to a hospital.
What you're describing is trying to make it so that people
don't get sick in the first place. Right.
Fitness trackers have proven benefits,
and the idea of preventative health care is really compelling.
I think it's just a different way to think about your own health.
It's changing from medicine being only about fixing problems,
to think of your health as preventing problems
from arising in the first place.
But I think I'm going to end on a note of caution.
As these devices get more and more sensors,
as they get more sophisticated,
we are going to amass this gigantic dataset of how an entire population
of people are living and exercising,
and, of course, can be an enormous source of good.
But I do also think, if we don't get things right with privacy
and security...
..that it could do quite a lot of damage, too.
Next time - the trainer.
It's the story of an American breakfast that inspired our "soles".
Look, I've got other skills, OK.
A family feud that created two of the biggest trainer brands.
They had different ideas, really, how to run the business.
Oh, and an 18th-century china tea set.
Anything not perfect is smashed.
To explore the interesting dilemmas behind some familiar pieces
of technology and to hear some of my own thoughts, go to -
and follow the links to the Open University.