Smart Materials

Shape memory alloy:

SMA's return to their original shape when heat is applied

Advantages	Disadvantages
Good mechanical properties Flexible Lightweight Durable	Expensive Can be overstressed Poor fatigue properties Difficult to repair

Uses: Braces, spectacles, planes, tweezers

Reactive glass:

Reactive glass goes from transparent to opaque when a current is passed through it

Advantages	Disadvantages
Multi-use Provides shade from harmful UV rays Can eliminate need for blinds/curtains in house Allows control of natural light levels Can be used as energy saving windows	Needs an external stimulus to work

Uses: Glass panels in buildings, privacy glass, auto-dimming rear-view mirrors

Phosphorescent pigment:

Emits light in dark conditions without a power source

Advantages	Disadvantages
Can absorb light energy and re-emit it Can be used in toys/products Inexpensive	Undetermined brightness Undetermined length of light emittance Needs to absorb natural light before it works

Uses: Fire exit signs, glow in the dark products, watch hands

Electroluminescent wire:

Wire that emits light

Advantages	Disadvantages
Safe/does not run hot Responds to stimuli (alternating current) Compact/flexible/adjustable	Can be expensive for long lenghts Can cause electric shocks during installation

Uses: Stage lights, neon signs

Photo-chromic materials:

change colours depending on light conditions (e.g. classes that also act as sunglasses)

Advantages	Disadvantages
Multiple uses Reacts to environment Reversible reaction	Expensive Sometimes doesn't fully react

Uses: Sunglasses, security sensors, UV light warning sensor, welding masks

Thermo-chromic materials:

change colours depending on temperature conditions

Advantages	Disadvantages
Multiple uses Reacts to environment Broad range of colours	Expensive Sometimes doesn't fully react Hard to make Takes time to fully react

Uses: Baby spoons, coffee mugs, batterys (charged or not)

Quantum tunnelling composites:

conduct electricity when pressure is applied

Advantages	Disadvantages
Good electrical insulator and conductor Flexible Durable Lightweight Water resistant	Relatively unknown technology Expensive Hard to manufacture

Uses: Power tool switches, robots, clothing/fabrics

Piezoelectric material:

an applied pressure produces a electrical current

Advantages	Disadvantages
Compact Flexible	Prone to water and moisture damage Highly sensitive to temperature Low voltage output

Uses: Airbag sensors, musical greeting cards, pressure sensors

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