Basic 8 · Career Technology · Smart and Modern Materials
Smart and Modern Materials in Products
In this topic you will discuss smart and modern materials in more detail, explain how their properties are used in everyday and industrial products, and evaluate their advantages and disadvantages.
By the end of these notes you should be able to:
- Explain how smart materials respond to stimuli
- Describe products that use smart and modern materials
- Evaluate the advantages and disadvantages of these materials
What you already know
- Smart and modern materials (Basic 7)
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
Lesson 1
- Strand
- Health And Safety
- Sub-strand
- Smart and Modern Materials
- Indicator
- B8.2.3.1.1 – Discuss smart and modern materials
Introduction
In Basic 7 you learned that smart materials change their properties when their surroundings change. Engineers use this behaviour to design products that respond automatically.
1. Smart Materials and Stimuli
| Smart material | Stimulus | Response | Product |
|---|---|---|---|
| thermochromic pigment | heat | changes colour | kettle indicators, baby feeding spoons, forehead thermometer strips |
| photochromic material | ultraviolet light | darkens | spectacle lenses, some window films |
| shape memory alloy (nitinol) | heat | returns to a remembered shape | dental braces, spectacle frames, medical stents |
| shape memory polymer | heat | returns to shape | self-repairing parts, packaging |
| piezoelectric material | pressure | produces electricity | gas lighters, sensors, microphones |
| hydrogel | water | absorbs water and swells | baby diapers, soil water crystals, wound dressings |
| smart grease and fluids | electricity or magnetism | change thickness | car suspensions |
2. Thermochromic Pigments
Thermochromic pigments contain special dyes that change colour at a set temperature. A baby's spoon may turn from pink to white when food is above about 40 °C, warning the parent that it is too hot. Thermometer strips placed on the forehead show different colours for normal and high temperatures. These products improve safety without needing batteries.
3. Shape Memory Alloys
Nitinol, an alloy of nickel and titanium, can be bent into a new shape when cool and will spring back to its original shape when warmed. Dental braces made from nitinol apply gentle, steady pressure as they warm in the mouth, slowly straightening teeth. Spectacle frames made from it can be bent and return to shape, making them hard to break.
4. Piezoelectric Materials
When pressed, piezoelectric crystals produce a small electric charge. In a gas lighter, pressing the button squeezes a crystal, creating a spark that lights the gas. The same effect is used in sensors in car airbags, electronic scales and some musical instruments.
5. Smart Materials in Agriculture and Health
Smart materials are also helping farmers and health workers. Hydrogel crystals mixed into the soil absorb rainwater and release it slowly to plant roots, helping crops survive dry spells. In hospitals, smart wound dressings keep wounds moist and some change colour to show infection. Shape memory alloy stents are inserted into narrowed blood vessels and expand at body temperature to keep them open. These uses show how smart materials save lives and improve food production.
New words
- stimulus
- A change in the surroundings that causes a response.
- thermochromic
- Changing colour with heat.
- nitinol
- A nickel-titanium shape memory alloy.
- piezoelectric
- Producing electricity when pressed.
Summary
- Smart materials respond to heat, light, pressure, water, electricity or magnetism.
- Thermochromic pigments warn of heat; shape memory alloys return to shape; piezoelectric materials produce sparks.
- These responses are used in safety, medical and household products.
Class activity: Smart Product Survey
- Examine samples such as reflective fabric, memory foam and packaging film.
- Identify products at home or in shops that use smart materials.
- Present how each product uses the material's response.
You need: Reflective fabric strip, Memory-foam sample, Food-packaging film
Exercises
Answer in your exercise book first, then check your answers.
1. A material that changes colour with heat is…
- A. thermochromic
- B. photochromic
- C. piezoelectric
- D. hydrogel
Show answer
Answer: thermochromicHeat.2. Nitinol is used in…
- A. dental braces
- B. bread
- C. cotton cloth
- D. cement
Show answer
Answer: dental bracesShape memory.3. Piezoelectric materials produce electricity when pressed.
- A. True
- B. False
Show answer
Answer: TruePressure.4. A change in surroundings that causes a response is a ______.
Show answer
Answer: stimulusTrigger.5. Name three smart materials and one product for each.
Show answer
Answer: Thermochromic: kettle indicator; photochromic: lenses; hydrogel: diapers.Any three.6. Explain how a thermochromic spoon improves baby safety.
Show answer
Answer: It changes colour when food is too hot, warning the parent before feeding.Heat warning.
Lesson 2
- Strand
- Health And Safety
- Sub-strand
- Smart and Modern Materials
- Indicator
- B8.2.3.1.1 – Discuss smart and modern materials
Introduction
Modern materials are developed to perform better than traditional ones. They make products stronger, lighter, safer or more comfortable.
1. Modern Materials and Their Uses
| Material | Special property | Uses |
|---|---|---|
| carbon fibre | very strong and very light | bicycles, racing cars, aircraft parts, sports equipment |
| Kevlar | extremely tough, resists cutting and heat | bulletproof vests, helmets, gloves |
| reflective fabric | reflects light back to its source | safety vests, school bags, road signs |
| memory foam | moulds to the body and slowly recovers | mattresses, pillows, shoe insoles |
| food-packaging film | keeps out air and moisture | wrapping food, extending shelf life |
| Teflon (PTFE) | non-stick and heat resistant | non-stick pans |
| microfibre | very fine fibres that trap dirt | cleaning cloths, sportswear |
| LED technology materials | produce light efficiently | bulbs, screens |
2. Evaluating Smart and Modern Materials
| Advantages | Disadvantages |
|---|---|
| improve safety (reflective vests, Kevlar) | usually expensive to buy |
| make products lighter and stronger | may need special factories and skills |
| increase comfort (memory foam) | some are difficult to recycle |
| save energy (LEDs) | some are imported, increasing costs |
| keep food fresh longer (packaging film) | some packaging adds to plastic waste |
3. Choosing Materials for a Product
Choose a material
A school wants safer uniforms for learners who walk along a busy road in the dark. Which material should be added?
- Need: drivers must see the learners at night.
- Option 1: bright cotton; seen only in daylight.
- Option 2: reflective fabric strips; reflect car headlights back to drivers.
- Cost: reflective strips are cheap enough to sew onto uniforms.
Answer: Reflective fabric strips, because they make learners visible to drivers at night at a low cost.
4. Smart Materials and Ghana's Future
As Ghana develops its industries, local businesses can use smart and modern materials, for example reflective strips for road safety campaigns, hydrogels to help farmers save water and improved packaging to reduce food waste. Learners interested in science and technology can become the engineers and designers who bring these materials into Ghanaian products.
New words
- carbon fibre
- A very strong, light modern material.
- Kevlar
- A very tough fibre used in protective clothing.
- microfibre
- A material made of very fine fibres.
- evaluate
- To judge the value and suitability of something.
Summary
- Modern materials include carbon fibre, Kevlar, reflective fabric, memory foam, packaging film and Teflon.
- They improve safety, strength, comfort and freshness but can be costly and hard to recycle.
- Choosing a material means matching its properties to the need and considering cost.
Class activity: Material Choice Challenge
- Read three product problems given by the teacher.
- Choose the best smart or modern material for each and explain why.
- Present your choices and their advantages and disadvantages.
You need: Reflective fabric strip, Memory-foam sample, Food-packaging film
Exercises
Answer in your exercise book first, then check your answers.
1. Which material is used in bulletproof vests?
- A. Kevlar
- B. cotton
- C. paper
- D. clay
Show answer
Answer: KevlarTough fibre.2. Non-stick pans are coated with…
- A. Teflon
- B. carbon fibre
- C. hydrogel
- D. nitinol
Show answer
Answer: TeflonPTFE.3. Some modern materials are difficult to recycle.
- A. True
- B. False
Show answer
Answer: TrueDisadvantage.4. To judge the value and suitability of something is to ______ it.
Show answer
Answer: evaluateJudge.5. State two advantages and two disadvantages of modern materials.
Show answer
Answer: Advantages: safety, strength. Disadvantages: expensive, hard to recycle.Two each.6. Explain why reflective fabric is suitable for learners walking at night.
Show answer
Answer: It reflects car headlights back to drivers, making learners visible and reducing accidents.Safety.
Homework
- Find three products at home made with smart or modern materials and evaluate one of them.