Have you ever thought of materials as being smart? Smart materials have properties that enable them to react to changes in their environment. This means that one of their initial properties can be changed by an external condition, such as temperature, light, pressure or electricity. This clever change is reversible and can be repeated many times. This is why science is interesting! There are many different smart materials. Each offer different properties that can be changed.
Shape-memory alloys
Most materials will remain in a bent position if you bend them out of shape. However, if a part made from a shape-memory alloy 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 as they can return to their original shape if they are put in hot water after bending them. SMAs are used as triggers to start the sprinklers in fire alarm systems, controllers for hot water valves in showers or coffee machines and for spectacle frames.
Quantum-tunnelling composite
Quantum-tunnelling composite is a flexible polymer which contains tiny metal particles. It usually acts as an insulator but when squeezed, it becomes a conductor. QTC can be used to make membrane switches like those used on mobile phones, pressure sensors and speed controllers. For Silicone Hose Manufacturers, visit https://www.goodflexrubber.com/pages/silicone-hose-manufacturer
Piezoelectric materials
Squeezing a piezoelectric material rapidly makes it produce a small electrical voltage for a moment. If a voltage is put across the material it makes a tiny change in shape. As such, Piezoelectric materials are being used for contact sensors for alarm systems and in microphones and headphones.
Colour-change materials
Thermochromic materials change colour as the temperature changes. You’ll find these being used on 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 lighting conditions. They are used for security markers that can only be seen in ultraviolet light.
Electroluminescent materials
When an electric current is applied to this material, it emits a light. Useful applications for such a material include safety signs and clothing for use at night.
New materials are being developed that contain properties which react to changes in the environment and although they will fall into one of the five main categories of material, they are often classed in a group of their own and referred to as smart materials. The five main categories are:
- wood
- metals
- polymers
- ceramics
- composites
Magnetic smart materials are used in a wide range of applications. Uses include brakes and high-performance shock absorbers for civil engineering, industrial and household appliances, medical appliances, and the automotive industry. Magnetic smart materials are also used as liquid sealants in a variety of devices, for example in computer hard drives. The material is useful in heat transfer and acts as a coolant for micro-systems based on thermomagnetic convection. These are some pretty smart materials indeed!