1.11 Smart Materials Flashcards
(13 cards)
Describe smart materials
Materials whose physical properties change in response to an input or change in the environment, such as electricity, pressure, temperature or light.
How does SMAs work?
SMA stands for Shape Memory Alloy — a modern smart material that can return to its original shape after being deformed, when exposed to a specific trigger (usually heat).
- Deformable at lower temperatures.
- Returns to preset shape when heated.
- Can undergo large strains and still recover.
usually metals eg. Nickel-Titanium (Nitinol) – most widely used SMA
State two uses of SMAs
- Medical Stents,
- orthodontic wires (braces)
- Aerospace Wing flaps
- Glasses frames
- Artificial muscles in robotics
How does thermochromic pigment work?
Changes colour in response to temperature
State three uses of thermochromic pigment
- Room thermometers
- Medical thermometers, for children
- Bath water thermometers
- Colour change mugs and kettles
- Food packaging
- Baby feeding spoons
- Battery charge indicator strips
How does phosphorescent pigment work?
Absorption: The pigment absorbs energy from a light source (e.g. sunlight or UV).
Excitation: Electrons in the pigment become “excited” and jump to a higher energy level.
Slow Release: Unlike fluorescence (which glows instantly), phosphorescence releases energy slowly, so it continues to glow in the dark for minutes or hours.
Return to Normal: Eventually, electrons return to their ground state, and the glow fades.
State two uses of phosphorescent pigment
- Fire exits signs
- ‘Glow in the dark’ products, such as adhesive stars, masks, night lights, and watch bands
How does photochromic pigment work?
Changes colour with light intensity
State two uses of photochromic pigment
- Welding goggles
- Reactive spectacle lenses
- Security marker that shows up under UV light
How does electroluminescent wire work?
Thin copper wire coated in a phosphorescent material that glows in response to an alternating current
State two uses electroluminescent wire
Batteries in the trainers provide DC power.
A small inverter converts this DC into low-voltage AC power.
The AC powers the EL wire in the shoe, making it glow.
The user controls it with a switch to turn the lights on or off.
eg.
- Light-up trainers (e.g. Nike Mag with glowing soles)
- Cycling safety vests that light up in the dark
- Mood lighting around mirrors, shelves, or desks
How does piezoelectric material work?
Piezoelectric materials generate an electric charge when they are mechanically stressed (pressed, bent, or squeezed).
Conversely, when an electric voltage is applied to them, they can change shape or vibrate.
State two uses piezoelectric material
Lighter igniters — pressing creates a spark to light a flame.
Electric toothbrushes — use tiny vibrations to clean teeth.
Doorbell buttons — pressing the button creates the signal to ring the bell.
