Lesson video

Hello there.

My name is Mrs. Dhami.

Thank you for joining me for your design and technology lesson today.

Now, the big question for today is what are smart materials? Now, this is one of my absolute favourite topics.

I think it's really exciting.

There are so many possibilities for the world of design with this.

So hard hats on.

Let's get cracking.

Our outcome for today is we will be able to describe the properties and uses of smart materials and give specific examples.

We have five keywords today.

Our first one is stimulus, which is the singular, and stimuli, which is the plural.

Basically, a stimulus is something that encourages activity or change, and we're going to explore quite a few of them today.

We then have physical and working properties.

I won't read those out now because I will go into more detail when we come to them.

Then to recap, we have function, which is the purpose of the product, and then we have form which is defined as a particular shape linked to aesthetics.

Basically how it looks.

Our lesson outline today will follow two learning cycles.

First of all, we're gonna define what smart materials are, and second, we are going to explore smart materials with loads of examples.

So let's get cracking with defining.

Take a little look at this GIF.

Watch what happens when the person touches the leaf of this plant.

Yep, you've got it? The leaf closes up.

So the mimosa pudica plant closes its leaves in response to the stimuli of touch.

So stimuli in this case is the touch.

Just like the mimosa pudica plant, smart materials appear to think by changing their properties in response to an external stimulus, but then they revert back to their original form when the stimulus is removed.

So let's define what we mean by properties.

We have, first of all, physical properties.

These are the characteristics of a material such as appearance and features.

Tends to be a bit more of the aesthetics.

So for example, if a product changes colour, its physical properties change.

Now, in contrast to this, we have working properties.

Working properties are the way in which a material responds to an external force or certain environment, and sometimes we refer to this as mechanical properties.

And a lovely example of this is when a product changes shape.

So keep these two at the forefront of your mind and feel free to come back to this slide or back to the keywords at any point.

This gives designers and engineers really exciting possibilities when developing new products.

Possibilities often focus on function and/or form.

So take a little look at my mom.

Here's my mom.

She's got her glasses on.

When she comes outside into the sunlight, you can see that her glasses change to sunglasses in response, there's that word response again, just like the mimosa plant, in response to sunlight.

So do the questions, do the glasses show a change in physical or working properties? Have a little think.

Come back to me when you've got an answer.

So Jacob says, "It has to be physical properties because it is a change in appearance." Well done, Jacob.

Time for a quick check in.

Smart materials can change their physical or working something in response to an external something.

Oh, nearly said the answers there, right.

Have a little think.

Come back to me when you've got an answer for both of them.

Hopefully, the first one you've got properties.

Smart materials can change their physical or working properties in response to an external stimulus.

Well done if you got that right.

So my next question for you is what could the stimuli be? So let's quickly recap what a stimuli is or a stimulus as the singular.

A stimulus is something that encourages activity or change.

So have a little look at my pictures, have a little think, maybe tell the person next to you and come back to me when you have got an idea.

Right, let's draw ourselves back together.

So let's take the first picture on the left, the stimuli here is sunlight.

Next one is water or moisture.

Next one is pressure, and the next one is temperature.

Well done if you managed to get those right.

Next check in.

In this example with Alex in the pictures, sunlight is the.

Now you can choose from property, stimulus, or smart material.

Have a little think.

Come back to me when you've got an idea.

Okay, well done for having a go.

Hopefully you got that in this example, sunlight is the stimulus.

Stimulus, remember, is what encourages activity or change.

It's the sunlight that encourages Alex's glasses to turn into sunglasses.

So we've looked at a few examples of stimuli.

Let's have a little look now at the changes in properties.

So one or more physical properties or working properties of smart materials can be changed.

So, for example, we have colour could change, opacity could change, and these are both physical properties.

Let's remind ourselves physical properties is all to do with appearance, and that fits lovely with the sunglasses example.

We also have properties where the shape can change and electrical conductivity can change.

And these are both examples of working properties.

Onto Task A.

First of all, I would like you to define the term smart material.

Then I would like you to sort the physical properties, working properties, and stimuli, which you can see here in purple, into the correct columns.

And here are our columns.

Have a think, have a go.

Good luck.

Join me back when you are ready.

Well done for your efforts with that.

So for the first part, I asked you to define what smart materials are.

Your answers could include: smart materials appear to think by changing their physical properties or working properties in response to an external stimulus.

Once the stimulus has been removed, the smart material goes back to its original form.

Part two, I asked you to sort out all of the terms into physical properties, working properties, and stimuli.

Now let's start with physical properties.

Remember, they are to do with things with appearance.

So well done if you got opacity and colour.

As for working properties, hopefully you found electrical conductivity and shape.

And then finally for stimuli, remember, that is something that encourages activity or change, and hopefully you got four in this column with temperature, pressure, light, and water/moisture.

Well done, folks.

Onto our second learning cycle where we are going to explore some wonderful examples of smart materials.

Have a little look at the GIF on the left-hand side.

Now you might have one of these mugs at home.

Now my question to you is what is the stimulus making this mug respond to its environment? Let's quickly remind ourselves about what a stimulus is.

A stimulus is something that encourages activity or change.

Have a little think.

Come back to me when you've got an idea.

So Sofia says, "It is the heat from the hot water," and she's absolutely right.

Hopefully you figured that out yourselves too.

Next question is what is the response to that stimulus? Have a little think.

Come back to me when you've got an answer.

So Sofia says, "The mug changes colour," and she's absolutely right.

The response is the change in colour.

Now we call this a thermochromic material.

Thermochromic materials change colour with response to heat.

So let's break up that word.

Thermo means heat, and that is the stimulus.

Chromic means colour, and that is the physical property response.

Thermochromic, with heat it changes colour.

As we identified at the start, smart materials can be used to design exciting new products to do with function and/or form.

So we're gonna break up the examples into function, form, or function and form.

So we're gonna start off with function for thermochromic materials.

Now, as you can see in this little GIF, this is an old spoon of my daughter's that she used to have when she was a baby.

Now it's being dipped into some very hot water there and hopefully you can notice that the colour is changing.

So thermochromic spoons can change colour to warn if the food is too hot.

If that spoon had changed colour, I knew not to feed that food to my daughter.

Now, another exciting one is bandages.

Bandages can be coloured with thermochromic dyes to change colour if a wound becomes too hot, which therefore indicates that the wound has become inflamed.

What a fantastic idea for the design of a product to help people out, especially maybe those people that find it difficult to communicate.

So a change in colour would clearly indicate that to the user and to the medical profession.

Let's take a little look at these two products on the right-hand side.

Now these I've put are a bit more function and form.

So we've already seen the mugs, so mugs and kettles can change colour with hot water, as really something fun, something to show people quite easily, not really necessarily as a warning, but I suppose it could be.

Then you also get bath toys that indicate if the bath water is too hot.

Again, that is great for a parent, they can quickly see if that water is far too hot.

But, equally, on a form basis, it's fun because the children will see the duck and will see that change in colour.

Quick check in.

What is the stimulus for a thermochromic material? Is it A, sunlight, B, water or moisture, or C, temperature? Have a think.

Come back to me when you've got an answer.

Okay, fantastic if you managed to get temperature.

Think of that baby spoon being put into that hot water, but don't think about it being water changing, it's the temperature of the water that makes the thermochromic spoon change.

Well done if you got that right.

Have a little look at the GIF on the left-hand side.

This is my daughter colouring in one of her books.

So my question is, what is the stimulus making this colouring book respond to its environment? Quick think.

Come back to me when you're ready.

Laura says, "It is the water," and she's absolutely right.

Next question, what is the response? Quick check in.

Have a think.

Come back to me when you're ready.

Laura goes on to say, "The colouring book changes colour." And again, she is absolutely right.

This is an example of a hydrochromic material.

It's a fantastic book that I take that is very, very mess free apart from a bit of water.

Hydrochromic materials change colour with response to water.

Now let's split up that word, hydrochromic.

We start off with hydro, and hydro means water, water being the stimulus.

Second part of the word is chromic.

We've seen that before, haven't we? Chromic meaning colour, and that is the physical property response.

The colour is changed.

A lovely example of hydrochromic materials are nappies.

Now you can buy some nappies that actually change colour to indicate that the nappy needs to be changed.

So on some examples, it's like a little line that changes colour.

But on this one, in this picture, if you look closely, there's a little picture of a guitar.

When the nappy is full, that guitar disappears to indicate that the nappy needs to be changed.

Great for new time parents, but also maybe great for nurseries too.

Another example is the one that we've already seen is the no mess colouring in books.

Function wise, that is great for me, I can take it out anywhere, and know that my daughter's not gonna make any mess.

A bit of water doesn't hurt anybody, but there's no felt tips, no colours going everywhere.

But for form wise, she loves it.

She absolutely loves seeing the pictures and the letters all of a sudden appear with the water.

Have a little look at the GIF on the left-hand side.

Now these are some beads that I am holding and I'm holding them close to a window.

In fact, I think you can see a bit of snow or ice on there.

So my question to you is, what is the stimulus making these beads respond to the environment? Have a little think.

Come back to me when you've got an idea.

Jun says, "I think it is the UV light." And he's absolutely right.

They were in a cupboard before and I'm placing them right by the window.

So what is the response? Have a little think.

Come back to me when you've got an idea.

Jun goes on to say, "The beads change colour." Now I know that's a little bit difficult to see, but if you look closely, those beads are starting to turn from white into a pastel colour.

And these beads are an example of a photochromic material.

Photochromic materials change colour with response to sunlight.

So let's break this word down like we did before.

The start of the word is photo, and that comes from the Greek word meaning light.

That is of course the stimulus.

Think of me putting those beads by the window, and then chromic, we've seen that before, haven't we? Again, it means colour.

And that is the physical property response.

We saw at the start of our lesson a brilliant example of photochromic materials, and that is the glasses that you saw my mom wearing.

When she goes outside, they change their opacity to sunglasses in response to sunlight.

Now, this is great for function because it means my mom doesn't have to keep changing between glasses.

Instead, she can wear one pair and they can do two jobs.

Another example is festival wear that uses UV lighting to illuminate and make the colours really bright.

This, of course, is more to do with form, obviously, than function.

Quick check in.

Which product out of these uses smart materials to focus more on function than form? Now, remember, form is more to do with appearance and aesthetics, the way a product looks.

So we have for A, we have the thermochromic mug, B, the thermochromic spoon, and C, the hydrochromic colouring book.

Have a little think.

Come back to me when you've got an answer.

Well done if you got B.

B is the thermochromic spoon and it really does have a great function to it, to warn parents or people feeding small children about the heat of the food, which could be a potential danger.

Have a little look at the GIF on the left-hand side.

You can see it is a paperclip and it is being pulled out of shape, and watch what happens when it goes into the pot, it springs straight back to its original shape.

So my question to you is, what is the stimulus making the misshaped paperclip respond to its environment? Have a think.

Come back to me when you've got an answer.

Sam says, "I think the water must be warm." And he's exactly right.

So what is the response? I think we've worked that out already.

Sam says, "It returns to the original paper clip shape," and that is absolutely right.

Now ,this is an example of a shape memory alloy.

Shape memory alloys.

So after deformation, the material appears to remember the original shape and returns to that original shape when heated.

Heat, of course, being the stimulus.

Now note this is a change in working properties, and it's the first example we have seen that changes in working properties.

All the others have been physical properties, so a change in appearance.

A great example of this are stents.

Now stents are tiny, tiny tubes that are threaded into arteries that expand with a rise in body temperature to allow increased blood flow.

Now this is for people who may have blocked arteries.

Isn't that absolutely amazing? Other examples of shape memory alloys include glasses that return to their original shape after bending, for example, if you accidentally sit on them on the sofa.

Another example are braces.

Now you might be sat there wearing a brace as we speak.

Braces use a shape memory alloy called nitinol that gently exert pressure to push the teeth back together.

Little did you know what you got inside your mouth.

And lastly, another example are memory foam pillows or mattresses.

Again, you might have one of these in your homes and they are examples of shape memory alloys, which really do focus on function a lot more than form.

Have a little look at the GIF on the left-hand side.

Now you will see in a second some tiny little white pellets.

That's how the material starts off.

And then you can see the material changes, can't you? And it's being moulded into another shape.

So in this example, you can see it's been moulded into a handle.

Now, it's quite an ergonomic handle because it means that it can be shaped to the person's specific hand shape.

So my question to you is, what is the stimulus making this material respond to its environment? Have a little think.

Come back to me when you've got an answer.

So Aisha says, "I think it is the heat from the hot water." And she's absolutely correct.

It's not the water itself, it's the heat from the hot water that makes them polymorph change state so that it can be moulded.

Which actually answers my next question, what is the response? And Aisha says, "It can be moulded into another shape." Absolutely correct.

Now the name of this wonderful smart material is polymorph.

You may or you may not have come across it in use at your school.

It is used for modelling orthopaedic or ergonomic aids, and for prosthetics.

Now, just in case you don't know, prosthetics are artificial body parts.

That's where maybe somebody who's lost a particular limb.

Therefore, it needs to be custom made.

And polymorph is great.

It can be absolutely custom made to whatever shape you want it to go in.

Polymorph is a polymer that melts when heated and can be moulded by hand into any shape.

Let's look at the word a bit more closely.

Poly comes from the Greek word meaning many, and morph from the Greek word meaning shape.

So, many shapes, and that's right, it can be made into lots of different shapes.

So the working property response is it can be moulded into lots of different shapes, hence the name.

Time for a check.

Which smart materials use heat as their stimulus? A, polymorph, B, photochromic, C, hydrochromic, D, thermochromic? Have a think.

Come back to me when you've got an answer.

Well done if you managed to identify two of them.

So A is polymorph that we've just seen.

And then D is thermochromic, which that was, if you remember, that was the spoon, the baby spoon going into the hot water and changing colour.

Well done if you got those right.

Piezoelectric materials are those that generate a small electric charge when you press, squeeze, or bend them.

It works the other way round though too.

They can move or make vibrations when electricity is sent through them.

Let's look at that word a little bit more closely.

Piezo is from the Greek word piezein, which means to press or to squeeze.

That is the stimulus.

Electric, well that simply means electric and that is the working property response.

Some examples of piezoelectric materials.

So first of all, we have a piezoelectric material generating a spark to ignite gas on a gas hob.

And then we have piezoelectric materials that convert vibrations from the strings into electric signals for amplification on an electric guitar.

What is the stimulus for a piezoelectric material? Is it A, electrical conductivity, B, pressure, or C, temperature? Have a little think.

Come back to me when you've got an answer.

Well done if you managed to get pressure.

Don't be confused with electrical conductivity, that is the response or a potential response, whereas pressure is the stimulus.

That's the input, that is the something that encourages activity or change.

Well done if you got that right.

Self-healing materials have the ability to detect and repair damage that they have undergone.

For example, bioconcrete uses bacteria that will react with water to heal itself by producing limestone to fill any micro cracks that appear.

How amazing is that? This is obviously a change in working properties, not physical properties as that would be appearance, working properties.

Onto Task B.

I would like you for part one to identify the stimulus for each smart material.

We have thermochromic, hydrochromic, shape memory, photochromic, piezoelectric, polymorph, and bioconcrete.

Have a go and fill in the chart.

Come back to me when you're ready.

Let's take a little look at your answers.

So the stimulus for thermochromic is heat.

The stimulus for hydrochromic is water.

The stimulus for shape memory is heat.

The stimulus for photochromic is sunlight.

The stimulus for piezoelectric is pressure.

The stimulus for polymorph is heat, and the stimulus for bioconcrete is water or moisture.

Well done if you got those right.

Task 2, have a little look at all of the products on the left-hand side of the chart.

We have colouring in using water, glasses that bend back if you sit on them, stents, glasses that turn into sunglasses, and baby spoons that change colour with hot food.

I would like you to identify, with a simple tick, whether these products are thermochromic, photochromic, hydrochromic, and shape memory.

Go through each one at a time and pop the tick in the right column.

Good luck.

Let's take a look at your answers.

You should have hydrochromic for colouring in using water.

Think of my daughter's colouring in book.

You should have shape memory for glasses that bend back to their original shape if you sit on them.

You should have shape memory again for stents.

Remember, those are the parts that go into arteries and expand to allow the blood to flow through.

You should have photochromic for glasses that turn into sunglasses.

Remember the example with my mom's glasses.

And then lastly, you should have thermochromic for baby spoons that change colour with hot food.

And remember that GIF where the pink baby spoon was going into the hot water and turned yellow because it was too hot.

Well done if you got those right.

The image on the right shows my daughter's bath toy.

For part three, I want you to explain how a smart material could be used to improve the toy.

Then for part four, I'd like you to discuss how smart materials have been used to improve the function and/or performance of products.

And I'd like you to use two examples to support your answer.

Good luck.

Come back to me when you've got some answers.

So let's take a look at your answers.

Remember there was the mermaid bath toy and I said, "How could you improve it with smart materials?" So an answer could include, "The bath toy could use a hydrochromic polymer.

Therefore, when the toy is played within the water, it could change colour, adding to the playful experience." And my daughter would love that, putting it under the cold tap and the hot tap and seeing the differences in colour.

Part four, your answers could go something like this.

"Smart materials appear to think by sensing the conditions in their environment and responding by changing their physical or working properties in a controlled way." There's the definition.

"An example of shape memory alloys, which can return to their original shape when heated, this is the working properties, these are used in glasses frames because if they get bent, they can go back to their original or proper shape, making them more durable." It means they will last for a lot longer because they can revert back to their original shape.

And remember I asked for two examples.

"Another example are thermochromic bandages.

These could be used in the medical profession as they change colour if a wound becomes infected, and this is the physical properties.

This would help busy wards and also people who may struggle with communication.

Overall, smart materials make products more useful, safer, and more convenient for people to use." Notice how that last paragraph concludes it, and that's a lovely way to finish an exam question.

Well done with all your hard work on that.

This brings us to the end of our lesson today.

Let's summarise what we found out.

Smart materials appear to think by changing their physical properties or working properties in response to an external stimulus.

Smart materials gives designers and engineers exciting possibilities when developing new products.

Stimuli can include sunlight, water or moisture, pressure, and temperature.

Physical properties that can be changed include colour and opacity.

Working properties that can be changed include shape and electrical conductivity.

Thermochromic, photochromic, hydrochromic, piezoelectric, polymorph, shape memory alloys, and bioconcrete are all examples of smart materials.

Oh, that was a long sentence to say.

Well done with all of your hard work today, and I hope to see you in another lesson soon.

Take good care, bye, bye, bye.