properties of smart materials

smart materials

STE PPP

• a material that responds to an external stimuli such as pressure, temperature or light

SMA (shape mempery alloy)

Used for braces, spectacles, aeroplane wing flaps, tweezers - return to their original shape when heat is applied

Advantages

• Good mechanical properties

• Flexible

• Lightweight

• Durable

Disadvantages

• Expensive

• Can be overstressed

• Poor fatigue properties

• Difficult to repair

thermochromic pigment

Used for thermometers, baby spoons, coffee mugs, batteries - changes colour in response to temperature change

Advantages

• Multiple uses

• Reacts to environment

• Broad range of colours

Disadvantages

• Expensive

• Sometimes doesn't fully react

• Hard to make

• Takes time to fully react

electroluminescent wire

Used for glow bracelets, stage lights, neon signs - wire that emits light (thin copper wire coated in phosphorescent material which glows in response to an alternating current)

Advantages

• Safe/does not run hot

• Responds to stimuli (alternating current)

• Compact/flexible/adjustable

Disadvantages

• Can be expensive for long lengths

• Can cause electric shocks during installation

phosphorescent pigment

Used for fire exit signs, glow in the dark products - emits light in dark conditions without a power source

Advantages

• Can absorb light energy and re-emit it

• Can be used in toys/products

• Inexpensive

Disadvantages

• Undetermined brightness

• Undetermined length of light emittance

• Needs to absorb natural light before it works

• absorbs light energy during the day and re-emits the light energy when it is dark

• used for fire exit signs, glow in the dark products

photochromic pigment

Used for sunglasses, security sensors, UV light warning sensor, welding masks - change colours depending on light conditions

Advantages

• Multiple uses

• Reacts to environment

• Reversible reaction

Disadvantages

• Expensive

• Sometimes it doesn't fully react

• changes colour with light intensity

• used for welding goggles, reactive spectacle lenses, security markers that show under UV

piezoelectric material

Used for airbag sensors, musical greeting cards, pressure sensors - an applied pressure produces a electrical current

Advantages

• Compact

• Flexible

Disadvantages

• Prone to water and moisture damage

• Highly sensitive to temperature

• Low voltage output