11. Smart materials

what is a smart material?

material whose physical properties change in response to input or change in environment

6 smart materials

SMAs e.g. nitinol

thermochromic pigment

phosphorescent pigment

photochromic pigment

electroluminescent wire

piezoelectric material

how can nitinol be used for dental braces?

transition temperature set as body temperature by passing electrical current through

when braces are in mouth the wire maintains a constant tension

how does SMA work?

changes shape in response to change in temperature or electrical input

give 4 uses of SMAs

dental braces

self-closing windows

aeroplane wing flaps

bioengineering such as stents

how does thermochromic pigment work?

changes colour as temp changes

3 uses of thermochromic pigment

room thermometers

baby feeding spoons

battery charge indicator strips

how does phosphorescent pigment work?

absorbs light energy in day and re-emits when dark

3 uses of phosphorescent pigment

fire exit signs

night lights

glow in the dark watch hands

how does photochromic pigment work?

changes colour with light intensity

3 uses of photochromic pigment

welding goggles

reactive glasses lenses

security markers that show under UV light

how does electroluminescent wire work?

thin copper wire coated in phosphorescent material

glows in response to alternating current

3 uses of electroluminescent wire

glow bracelets

interweaving for clothing

home decoration

how does piezoelectric material work?

gives off small electrical charge when deformed

increases in size (up to 4%) when electrical current passed through

3 uses of piezoelectric material

airbag sensors in cars

barbecue lighters

pressure sensors