The artificial muscles that will power robots of the future

Robot brains are getting smarter and smarter, but their bodies are often still clunky and unwieldy. Mechanical engineer Christoph Keplinger is designing a new generation of soft, agile robot inspired by a masterpiece of evolution: biological muscle. See these "artificial muscles" expand and contract like the real thing and reach superhuman speeds -- and learn how they could power prosthetics that are stronger and more efficient than human limbs.

In 2015, 25 teams from around the world

competed to build robots
for disaster response

that could perform a number of tasks,

such as using a power tool,

working on uneven terrain

and driving a car.

That all sounds impressive, and it is,

but look at the body
of the winning robot, HUBO.

Here, HUBO is trying to get out of a car,

and keep in mind,

the video is sped up three times.

(Laughter)

HUBO, from team KAIST out of Korea,
is a state-of-the-art robot

with impressive capabilities,

but this body doesn't look
all that different

from robots we've seen a few decades ago.

If you look at the other robots
in the competition,

their movements also still look,
well, very robotic.

Their bodies are complex
mechanical structures

using rigid materials

such as metal and traditional
rigid electric motors.

They certainly weren't designed

to be low-cost, safe near people

and adaptable to unpredictable challenges.

We've made good progress
with the brains of robots,

but their bodies are still primitive.

This is my daughter Nadia.

She's only five years old

and she can get out of the car
way faster than HUBO.

(Laughter)

She can also swing around
on monkey bars with ease,

much better than any current
human-like robot could do.

In contrast to HUBO,

the human body makes extensive use
of soft and deformable materials

such as muscle and skin.

We need a new generation of robot bodies

that is inspired by the elegance,
efficiency and by the soft materials

of the designs found in nature.

And indeed, this has become
the key idea of a new field of research

called soft robotics.

My research group
and collaborators around the world

are using soft components
inspired by muscle and skin

to build robots with agility and dexterity

that comes closer and closer

to the astonishing capabilities
of the organisms found in nature.

I've always been particularly inspired
by biological muscle.

Now, that's not surprising.

I'm also Austrian, and I know that I sound
a bit like Arnie, the Terminator.

(Laughter)

Biological muscle
is a true masterpiece of evolution.

It can heal after damage

and it's tightly integrated
with sensory neurons

for feedback on motion
and the environment.

It can contract fast enough
to power the high-speed wings

of a hummingbird;

it can grow strong enough
to move an elephant;

and it's adaptable enough
to be used in the extremely versatile arms

of an octopus,

an animal that can squeeze
its entire body through tiny holes.

Actuators are for robots
what muscles are for animals:

key components of the body

that enable movement
and interaction with the world.

So if we could build soft actuators,

or artificial muscles,

that are as versatile, adaptable

and could have the same performance
as the real thing,

we could build almost any type of robot

for almost any type of use.

Not surprisingly,
people have tried for many decades

to replicate the astonishing
capabilities of muscle,

but it's been really hard.

About 10 years ago,

when I did my PhD back in Austria,

my colleagues and I rediscovered

what is likely one of the very first
publications on artificial muscle,

published in 1880.

"On the shape and volume changes
of dielectric bodies

caused by electricity,"

published by German physicist
Wilhelm Röntgen.

Most of you know him
as the discoverer of the X-ray.

Following his instructions,
we used a pair of needles.

We connected it to a high-voltage source,

and we placed it near
a transparent piece of rubber

that was prestretched
onto a plastic frame.

When we switched on the voltage,

the rubber deformed,

and just like our biceps flexes our arm,

the rubber flexed the plastic frame.

It looks like magic.

The needles don't even touch the rubber.

Now, having two such needles
is not a practical way

of operating artificial muscles,

but this amazing experiment
got me hooked on the topic.

I wanted to create new ways
to build artificial muscles

that would work well
for real-world applications.

For the next years, I worked
on a number of different technologies

that all showed promise,

but they all had remaining challenges
that are hard to overcome.

In 2015,

when I started my own lab at CU Boulder,

I wanted to try an entirely new idea.

I wanted to combine
the high speed and efficiency

of electrically driven actuators

with the versatility
of soft, fluidic actuators.

Therefore, I thought,

maybe I can try using
really old science in a new way.

The diagram you see here

shows an effect called Maxwell stress.

When you take two metal plates

and place them in a container
filled with oil,

and then switch on a voltage,

the Maxwell stress forces the oil
up in between the two plates,

and that's what you see here.

So the key idea was,

can we use this effect to push around oil

contained in soft stretchy structures?

And indeed, this worked surprisingly well,

quite honestly,
much better than I expected.

Together with my
outstanding team of students,

we used this idea as a starting point

to develop a new technology
called HASEL artificial muscles.

HASELs are gentle enough
to pick up a raspberry

without damaging it.

They can expand and contract
like real muscle.

And they can be operated
faster than the real thing.

They can also be scaled up
to deliver large forces.

Here you see them lifting
a gallon filled with water.

They can be used to drive a robotic arm,

and they can even
self-sense their position.

HASELs can be used
for very precise movement,

but they can also deliver
very fluidic, muscle-like movement

and bursts of power
to shoot up a ball into the air.

When submerged in oil,

HASEL artificial muscles
can be made invisible.

So how do HASEL artificial muscles work?

You might be surprised.

They're based on very inexpensive,
easily available materials.

You can even try, and I recommend it,

the main principle at home.

Take a few Ziploc bags
and fill them with olive oil.

Try to push out air bubbles
as much as you can.

Now take a glass plate
and place it on one side of the bag.

When you press down,
you see the bag contract.

Now the amount of contraction
is easy to control.

When you take a small weight,
you get a small contraction.

With a medium weight,
we get a medium contraction.

And with a large weight,
you get a large contraction.

Now for HASELs, the only change
is to replace the force of your hand

or the weight with an electrical force.

HASEL stands for "hydraulically amplified
self-healing electrostatic actuators."

Here you see a geometry
called Peano-HASEL actuators,

one of many possible designs.

Again, you take a flexible polymer
such as our Ziploc bag,

you fill it with an insulating liquid,
such as olive oil,

and now, instead of the glass plate,

you place an electrical conductor
on one side of the pouch.

To create something
that looks more like a muscle fiber,

you can connect a few pouches together

and attached a weight on one side.

Next, we apply voltage.

Now, the electric field
starts acting on the liquid.

It displaces the liquid,

and it forces the muscle to contract.

Here you see a completed
Peano-HASEL actuator

and how it expands and contracts
when voltage is applied.

Viewed from the side,

you can really see those pouches
take a more cylindrical shape,

such as we saw with the Ziploc bags.

We can also place a few
such muscle fibers next to each other

to create something that looks
even more like a muscle

that also contracts and expands
in cross section.

These HASELs here are lifting a weight
that's about 200 times heavier

than their own weight.

Here you see one of our newest designs,
called quadrant donut HASELs

and how they expand and contract.

They can be operated incredibly fast,
reaching superhuman speeds.

They are even powerful enough
to jump off the ground.

(Laughter)

Overall, HASELs show promise
to become the first technology

that matches or exceeds the performance
of biological muscle

while being compatible
with large-scale manufacturing.

This is also a very young technology.
We are just getting started.

We have many ideas how to
drastically improve performance,

using new materials and new designs
to reach a level of performance

beyond biological muscle and also beyond
traditional rigid electric motors.

Moving towards more complex designs
of HASEL for bio-inspired robotics,

here you see our artificial scorpion

that can use its tail to hunt prey,

in this case, a rubber balloon.

(Laughter)

Going back to our initial inspiration,

the versatility of octopus arms
and elephant trunks,

we are now able to build
soft continuum actuators

that come closer and closer
to the capabilities of the real thing.

I am most excited
about the practical applications

of HASEL artificial muscles.

They'll enable soft robotic devices

that can improve the quality of life.

Soft robotics will enable a new generation
of more lifelike prosthetics

for people who have lost
parts of their bodies.

Here you see some HASELs in my lab,

early testing,
driving a prosthetic finger.

One day, we may even merge
our bodies with robotic parts.

I know that sounds very scary at first.

But when I think about my grandparents

and the way they become
more dependent on others

to perform simple everyday tasks
such as using the restroom alone,

they often feel like
they're becoming a burden.

With soft robotics, we will be able
to enhance and restore

agility and dexterity,

and thereby help older people
maintain autonomy

for longer parts of their lives.

Maybe we can call that
"robotics for antiaging"

or even a next stage of human evolution.

Unlike their traditional
rigid counterparts,

soft life-like robots will safely operate
near people and help us at home.

Soft robotics is a very young field.
We're just getting started.

I hope that many young people
from many different backgrounds

join us on this exciting journey

and help shape the future of robotics

by introducing new concepts
inspired by nature.

If we do this right,

we can improve the quality of life

for all of us.

Thank you.

(Applause)