we've already covered a good amount of engineering history.

Civil, mechanical, electrical, and chemical are the four main branches of engineering.

But there are many others!

Some have been around for centuries, while others have developed more recently and are rapidly growing.

Some have even broken off of existing branches and are quickly becoming their own fields.

One example of this is aerospace engineering, which handles the design and construction of air and spacecraft.

This was a natural progression from mechanical engineering, as we started creating machines that could fly.

Another example is environmental engineering, which uses engineering practices, soil science, biology, and chemistry to help find solutions to environmental problems.

We'll cover these and others in more detail later on, but for now let's focus on two of the more prominent disciplines of engineering: industrial and biomedical.

After we learn about the history of these two branches,

we're going to see what it would take to use both of these fields to build and design a fully-functioning artificial limb.

So stick around!

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Industrial engineering has been around as long as we've had factories and other engineering systems.

Just as mechanical engineers work with a bunch of different parts to design a machine,

industrial engineers work with many different elements to devise an efficient system.

And it's not just the machines they have to think about.

They also have to consider the workers, materials, energy flow, and communication that are needed to provide the best product or service.

Other branches of engineering often take apart each system and analyze all of its parts separately, before putting a system together.

But industrial engineers do things a bit differently.

They look at the system as a whole first and then move on to see how the different parts work together.

Then they can focus on the specifics to achieve the best results.

It's all about optimization.

And one of the most important areas that industrial engineers try to optimize is the assembly line.

It's where we can see the biggest improvements in quality, delivery time, and cost.

The drive to optimize the assembly line is why many factories have switched over to more automation instead of manual labor.

And it's caused the idea of “lights-out manufacturing” to grow,

which is where factories and manufacturing operations don't physically need humans there to run or operate.

Some machines are far less concerned about needing light, or heat and air conditioning, for that matter.

And they're much less likely to complain.

But we're still a long wayfrom a world where robots and machines run everything.

Until then, we can learn a good deal from Frederick Winslow Taylor,

an American engineer who we see as the father of industrial engineering and scientific management.

Around 1881, Taylor introduced what we know as time study.

He found that the efficiency in a shop or factory could be greatly improved by looking at the workers and eliminating as much wasted time as was reasonably possible.

His work led to major improvements in factory production by focusing on one of the biggest variables: people.

Taylor's teachings soon became widespread, with his work titled The Principles of Scientific Management being published in 1911.

While industrial engineering might not be as flashy as some of the other professions, it's central to the overall function of the other branches.

It's the backbone of our engineering skelton.

It's been in the background of engineering ever since we built the first factories.

Which brings us to one of the new fields of engineering: biomedical.

It's often used synonymously with bioengineering, but the two are not exactly the same.

Biomedical engineering applies engineering skills and principles to biology and medicine, usually for the purpose of healthcare.

It focuses on human and animal biology, whereas bioengineering is typically used as a broader term that can include other biological systems, like plants.

Biomedical engineering focuses on advancements that improve our health, from diagnosis and analysis of medical conditions, to their treatment and recovery.

This is where we'll learn the skills to try and make an artificial limb.

Biomedical engineers differ a bit from the other disciplines in that they often need to apply modern biological principles to their designs.

For example, you have to make sure that the materials of an artificial organ don't cause an unwanted reaction inside the body,

and that an artificial limb moves in similar ways to its organic counterpart.

As such, biomedical engineers need to have a good working knowledge of many other fields

in addition to biology, including mechanical and electrical engineering, materials science, and chemistry, to name a few.

And biomedical engineering shows up in most of our lives.

Beyond artificial limbs and organs, we have it thank for defibrillators, pacemakers, MRI and CT scans, and insulin pumps.

It's striking to think that most of these technologies weren't around 50 or 100 years ago.

That's because biomedical and bioengineering didn't really show up until after World War II.

There were certainly biomedical inventions before that, but they were mostly left to the doctors and physicians.

Some of the earliest evidence for the practice that we've found has been a 3,000 year-old wooden and leather prosthetic toe found on an Egyptian mummy.

Moving forward to about 200 years ago, the French physician René Laënnec came up with an important biomedical invention: the stethoscope.

After being appointed as a physician in the Necker Hospital in Paris in 1816,

he developed the stethoscope in response to how uncomfortable it was to have to lay your ear on a person's chest to listen to their heart or lungs.

People who enjoy their personal space have been thankful ever since.

X-ray imaging was another early biomedical discovery.

In 1895, German physicist Wilhelm Conrad Röntgen discovered X-rays while experimenting with electric current flow.

He took the first X-ray photographs, which included the interiors of metal objects and the bones of his wife's hand.

Even simple crutches and walking sticks can be looked at as early biomedical devices.

There was a medical problem, and people used what they had available to them to improve their situation.

But biomedical engineering didn't really take off until 1961,

when the University of Pennsylvania offered the Ph.D. Program of Biomedical Electronic Engineering, the first in the United States.

Now that the field was more established, one of the biggest steps forward for biomedical engineering was computers.

With computers, we could begin to analyze data much faster, which made it more efficient to evaluate patients, and opened up new ways of doing so.

Along with the invention of the internet, this is what's allowed doctors and physicians to create a worldwide network of data to find medical patterns and correlations.

It also led to new imaginingng opportunities like the MRI and CT scans, which began to pick up in the 1970's.

Moving forward, advancements in medical instruments and electronics continue to be a major goal of biomedical engineers.

They continue to seek the answers to questions like 'How can we better take images of the body?

Can we reduce any radiation involved?

Can we come up with better analysis and measurement systems?

How many tests can we do from a single drop of blood?'

But there are still some major challenges that biomedical engineers are wrestling with.

One of them is biological modeling.

We want to know – how we can simulate the body and what's happening inside it.

If we can get a realistic and reliable simulation, then we can use it to run experiments on rather than using a real person.

It would allow us to both experiment in ways that could be harmful to a real person and also repeat tests more than we normally could.

Another area we'd like to learn more about is drug delivery.

We want the medicine that we create to get where it needs to go.

This is because certain medicine and treatments become less effective depending on where and how they're delivered.

It's also important to know how the body will react to any implanted biomachines.

This is where materials science really comes in.

One of the more interesting recent developments here is called cell encapsulation.

This is where we surround a cell in biomaterials so that it's protected inside the body.

The materials can act as barriers to protect a transplanted cell from being attacked by its host's immune system.

The technology is somewhat new, but it has the potential to do wonders for cell-based therapy.

Materials are also important as we develop prosthetics even further.

When we're replacing something like a hip or a limb, there are many potential issues that we need to worry about.

Some of these include making sure that bacteria and infections won't thrive on the material we've implanted and that the material is durable and will last a long time.

Let's look at what it might take to replace a fully-functional leg.

There are many more factors at play than we'll go over for now, but let's look at the big ones.

To start off, strength of materials is going to be pretty important.

We need the mechanical “bones” of the leg to not only last, but to handle both the static and dynamic forces that a leg goes through.

A material that handles the constant stress and strain of standing might not hold up well to the forces that happen when we run.

Once that's figured out, we'll need to look into power and electrical engineering if we want it to move, like one of our legs.

This is also where programming and computer science might play a big role.

Furthermore, it's not just the strong, rigid materials that we'll have to worry about.

For instance, our knees and many parts of our bodies contain cartilage, which act, in part, as shock absorbers.

There are also fluids in our knees that help them move, called synovial fluids.

Finding out how to replicate these, with things like hyaluronic acid, could go a long way in recreating an artificial leg.

Now, once we've figured out the design for the leg, we'll want to go back to our teachings about industrial engineering in order to make them in a factory.

Not only will it be good to make them efficiently, but we'll also want to make sure they're made with the best possible quality.

You see, we have the potential to do great things when we apply what we've learned.

Like most engineering pursuits, things really come together when we combine at least a few of the different fields.

So today we started off by learning about industrial engineering and the different factors involved in an industrial system.

We talked about Frederick Winslow Taylor, the father of industrial engineering, and his work with scientific management.

Then we moved on to biomedical engineering and bioengineering, along with their early inventions.

Finally, we ended our lesson by talking about the future of the biomedical field and saw what it might be like to bring our teachings together in creating an artificial leg.

Next time we'll be moving on from our history-based lessons into thermodynamic and the laws of conservation.

Thanks for watching and I'll see you then.

Crash Course Engineering is produced in association with PBS Digital Studios.

You can head over to their channel to check out a playlist of their amazing shows, like

The Art Assignment, Deep Look, and It's Okay to Be Smart.

Crash Course is a Complexly production and this episode of was filmed in the Doctor Cheryl C. Kinney Studio with the help of these wonderful people.

And our amazing graphics team is Thought Cafe.