1.2 Classification of smart materials

SMAs, e.g. nitinol

Changed shape in response to a change in temperature or electrical input. (nitinol wire in dental braces changes length in response to a change in temperature) -Used in dental braces, self closing windows, aeroplane Wong flaps, bioengineering such as stents, bone plates and screws.

Thermochromic pigment

A smart material which changes colour in response to a change in temperature e.g. forehead thermometer

Phosphorescent pigment

Absorbs light energy during the day and 're-emits' the light energy when it is dark. Used in fire exit signs. glow in the dark products such as adhesives stars and masks.

Photochromic pigments

A smart material which changes colour in response to a change in light e.g. sunglasses which tint in sunlight

Electroluminescent wire

Thin copper wire coated in a phosphorescent material that glows in response to an alternating current.Used in glow bracelets, interweaving for clothing, home decoration and outdoor decorative lighting.

Piezoelectric material

A smart material which gives off small electrical charges when deformed. It increases in size when a current passes through it e.g. airbag sensors