Hello and welcome to this edition of Tomorrow's Tech
in the Department of Mechanical Engineering at UCL.
Today I will talk to one of our PhD students, Anastasia.
Tell me a bit about what you do.
My project is to understand how fluids behave,
because this can help make oral health products better.
It starts with things in a kitchen cupboard that behave differently.
We have some honey and water. Tell me about the differences.
As you can see, if I try to pour water, it flows very easily,
so this means it has a very low viscosity.
If I try to mix it or do something, its behaviour doesn't change.
This means it is a Newtonian fluid.
If I try to pour honey,
I might face resistance.
Honey has a higher viscosity.
We know that water is very runny,
and that honey is very viscous and they are different fluids,
but there are fluids that can behave in both ways, depending on what you do.
A very simple example of this kind of fluid
is a toothpaste that we use everyday.
The speed that we brush our teeth has an impact on how it will behave,
either as a solid or as a liquid.
For example, I have some toothpaste here,
and I can show you that if I keep it like that,
it doesn't drop down,
but when I squeeze the tube
a nice ribbon of toothpaste is a solid on the toothbrush.
When we are trying to brush our teeth,
this means we apply some force on it,
and it starts to behave like a liquid.
It can satisfy consumer needs.
It also lets the active ingredients go onto the teeth.
It helps the health of the teeth.
The toothpaste doesn't change,
but when you hold it in the tube it's like a solid,
and when you squeeze it, it becomes like a liquid,
just while it's moving, and then it becomes a solid again.
Then you brush your teeth and it becomes like a liquid.
One of the ingredients it contains helps it to change its form
dependent on what we do and how we do it,
the speed we do it and the length of time we do it.
This is a special class of materials
because the way that they behave
depends on how quickly you push them.
These kinds of fluids are called non-Newtonian.
This is very important because
if we understand how the separate ingredients of the toothpaste work.
Then we can combine all of them
and provide products with better properties,
as well as introducing new manufacturing processes,
that will be less time- and energy-consuming.
There are four important ingredients in a toothpaste.
First we have a matrix,
that is formed without water.
It is mostly glycerol.
The glycerol here is what everything else is in?
That's the container?
This is the main matrix.
Then, to introduce this non-Newtonian behaviour,
we have some polymers.
We can imagine them as little chains
that form networks
and the other ingredients are trapped and encapsulated in this network,
so that they can be there until we apply a stress.
This is the matrix we use.
We have abrasive particles as cleaning agents
and these particles are strange in morphology.
There are also some other types of particles,
so that we can control the thickness of our product.
The other ones have a similar morphology,
but they are there as thickeners.
Thickeners can also help to keep the active ingredients
within the matrix.
They are released in a controlled way when we brush our teeth.
We might think we've all been using toothpaste for years,
that toothpaste is all sorted out,
but you're saying toothpaste could get even better.
The oral health industry is today worth almost 1 billion in the UK every year.
If we find a way to understand
how the ingredients of oral health products behave on their own,
we can make better toothpastes,
so the better we make these products,
we improve both the industry and the health of consumers.