Smart Materials

Question 1

Describe, give the property of and uses of: Piezoelectric materials

Answer 1

When a piezoelectric material is squeezed rapidly, it produces a small electrical voltage for a moment. If a voltage is out across the material it makes a tiny change in shape.
Piezoelectric materials are being used for contact sensors for alarm systems and in microphones and headphones

Question 2

Describe, give the property of and uses of: Quantum Tunnelling Composite

Answer 2

QTC is a flexible polymer which contains tiny metal particles. It is normally an insulator but if it is squeezed it becomes a conductor. QTC can be used to make membrane switches like those used in mobile phones, pressure sensors and speed controllers

Question 3

Describe, give the property of and uses of: Electrolumines Cent materials

Answer 3

Electroluminescent materials give out light when an electric current is applied to them. Among many possible applications are safety signs and clothing for use at night

Question 4

Describe, give the property of and uses of: Colour-change materials

Answer 4

Thermochromic materials change colours as temperature changes. These are used on contact thermometers made from plastic strips and test strips on the side of batteries (where the heat comes from a resistor under the thermochromic film). They are also used as food packaging materials that show you when the product they contain is cooked to the right temperature.
Photochromic materials change colour according to different light conditions. They are used for security markers that can only be seen in ultraviolet light

Question 5

Describe, give the property of and uses of: Shape Memory Alloy

Answer 5

For most materials, if they are bent out of shape, they stay that way. However, if a part made from a SMA is bent out of shape, when it is heated above a certain temperature it will return to its original shape.
This property makes it useful for making spectacle frames- they return to their original shape if they are put in hot water after bending them.
SMA’s are also used as triggers to start sprinklers in fire alarm systems, controllers for hot water valves in showers or coffee machines