What are smart and modern materials, and how does their changing behaviour make them useful?
Smart and modern materials: shape memory alloys, thermochromic and photochromic materials, quantum tunnelling composite and other responsive materials, and their uses.
A CCEA GCSE Technology and Design answer on smart and modern materials: shape memory alloys, thermochromic and photochromic pigments, quantum tunnelling composite and other materials whose properties change in response to a stimulus, and where they are used.
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What this dot point is asking
CCEA wants you to define a smart material, to know the main examples - shape memory alloys, thermochromic and photochromic materials, quantum tunnelling composite and similar responsive materials - and to explain how their changing behaviour is put to use. The key idea is a property that changes in response to a stimulus.
The answer
What makes a material "smart"
This is what separates a smart material from an ordinary one: it actively reacts to its environment rather than staying fixed. "Modern materials" is a slightly broader term that also includes newly developed materials with useful properties.
Shape memory alloys
Uses include spectacle frames that spring back after being bent, dental braces that keep pulling teeth as they warm to body temperature, and thermal actuators that open a vent when it gets hot.
Thermochromic and photochromic materials
Thermochromic pigments appear in colour-changing mugs, battery test strips, kettles that show when hot, and forehead thermometers. Photochromic materials are used in glasses lenses that darken in sunlight and lighten indoors.
Quantum tunnelling composite and other responsive materials
QTC is used in flexible touch switches and in fabric controls. Piezoelectric materials are used in some sensors and buzzers. These link materials to the electronics topics, because their changing electrical behaviour can be used as an input or output in a control system.
Worked example: choosing a smart material for a product
Examples in context
- Example 1. Reactive sunglasses
- Photochromic lenses darken in bright sunlight and clear indoors, removing the need to swap glasses - a reversible response to ultraviolet light.
- Example 2. A kettle "hot" indicator
- A thermochromic panel changes colour as the kettle heats, warning the user the surface is hot without any wiring or battery.
- Example 3. A flexible touch pad
- QTC printed into a fabric lets a jacket sleeve work as a touch control: pressing it lowers the resistance so current flows, switching a device on.
Naming the right smart material, the stimulus and the property change lets you answer "what is a smart material" and "explain how it works" questions precisely.
Try this
Q1. Define a smart material. [1 mark]
- Cue. A material whose properties change in response to a stimulus (temperature, light, force or electricity).
Q2. What stimulus does a thermochromic material respond to? [1 mark]
- Cue. Temperature (it changes colour with heat).
Q3. Give one product that uses a shape memory alloy. [1 mark]
- Cue. Spectacle frames, dental braces or a thermal actuator.
Q4. Explain how quantum tunnelling composite (QTC) can act as a switch. [2 marks]
- Cue. It is an insulator when relaxed but conducts when squeezed, so pressure turns it from non-conducting to conducting.
Q5. State one use of a photochromic material. [1 mark]
- Cue. Glasses lenses that darken in sunlight and lighten indoors.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA style3 marksWhat is meant by a smart material? Give one example and one use.Show worked answer →
A smart material is one whose properties change in response to a change in its surroundings (a stimulus) such as temperature, light, force or electricity (1).
Example: a thermochromic pigment, which changes colour with temperature (1). Use: a colour-changing label on a battery or kettle that shows when it is hot or charged (1).
CCEA style4 marksExplain how a shape memory alloy works and give one product that uses it.Show worked answer →
A shape memory alloy can be bent or deformed when cool, but returns to its original, remembered shape when it is heated above a set temperature (1), and it can repeat this many times (1).
It works because heating triggers a change in its internal structure back to the original form (1). A product that uses it is spectacle frames that spring back into shape after being bent, or a thermostatic actuator (1).
Related dot points
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A CCEA GCSE Technology and Design answer on shaping and forming processes: marking out, wasting (sawing, filing, drilling), deforming such as line bending, and reforming processes including vacuum forming and injection moulding of plastics.
- Design influences and sustainability: consumer demand, the market, consumer law and standards, and designing sustainably using the six Rs.
A CCEA GCSE Technology and Design answer on the factors that influence design - consumer demand, the market, customer expectations, consumer law and standards - and on designing sustainably using the six Rs to reduce environmental impact.
- Input subsystems: switches, the light-dependent resistor, the thermistor, and the voltage divider that turns a sensor's resistance change into a voltage signal.
A CCEA GCSE Technology and Design answer on input subsystems: switches, the light-dependent resistor (LDR) and the thermistor, and how a voltage divider (potential divider) turns a change in a sensor's resistance into a changing voltage signal for the process stage.
- The systems approach: representing electronic and control systems as input, process and output blocks, with feedback, using block (systems) diagrams.
A CCEA GCSE Technology and Design answer on the systems approach: describing an electronic or control system as input, process and output blocks, the idea of feedback, and using block (systems) diagrams to design and analyse a system.
Sources & how we know this
- CCEA GCSE Technology and Design specification — CCEA (2017)
- CCEA Factfile 1.8: Smart Materials — CCEA (2019)