Smart Materials: Transforming Design Through Responsiveness
Smart Materials
Materials that respond to external stimuli (such as heat, light, pressure, or electricity) by changing one or more of their properties in a controlled, reversible, and repeatable way.
External stimuli include:
- Temperature
- Pressure
- Light
- Magnetic fields
- Electric fields
Key Types of Smart Materials
Piezoelectric Materials
Piezoelectricity
A property of certain smart materials that allows them to generate a small electrical charge when mechanically deformed, and to change shape (expand or contract) when an electric current is applied.
- Stimulus - Mechanical stress
- Response - Generates electrical charge (and vice versa)
- Sensors: Used in microphones and accelerometers.
- Actuators: Employed in precision movement devices like inkjet printers.
- Energy Harvesting: Converts vibrations into electricity for low-power devices.
Shape Memory Materials
Shape Memory Materials
A smart material that can be deformed and then return to its original, pre-set shape when exposed to a change in temperature or stress.
- Stimulus - Heat
- Response - Returns to original shape after deformation
- Common types:
- Shape Memory Alloys (SMAs)
- Shape Memory Polymers (SMPs)
- Medical Devices: Stents and orthodontic wires.
- Aerospace: Adaptive wing structures.
- Consumer Products: Eyeglass frames that return to shape after bending.
Photochromic Materials
Photochromicity
Photochromic materials change color in response to light and revert when the light is removed.
- Stimulus - UV light
- Response - Changes colour
- Eyewear: Transition lenses that darken in sunlight.
- Security: Anti-counterfeiting measures in currency and documents.
- Fashion: Color-changing fabrics for dynamic designs.
Think of photochromic materials like a chameleon that changes color based on its surroundings, providing protection or camouflage.
Magneto-Rheostatic Materials
Magneto-rheostatic
Magneto-rheostatic (MR) fluids are special liquids that become thicker or more solid when a magnetic field is applied. When the magnetic field is removed, they return to their normal liquid state. This makes them useful in things like car suspension systems and vibration control.
- Stimulus - Magnetic field
- Response - Changes viscosity (stiffens or softens)
Automotive: Adaptive suspension systems for smoother rides, MR fluids adjust suspension stiffness in real time based on road conditions.
Electro-Rheostatic Materials
Electro-rheostatic
Electro-rheostatic (ER) fluids are special liquids that can quickly become thicker or more solid when an electric field is applied. When the electricity is turned off, they go back to being a normal liquid. This makes them useful in things like shock absorbers and brakes.
- Stimulus - Electrical field
- Response - Changes viscosity (stiffens or softens)
- Industrial: Clutches and brakes with variable resistance, ER fluids allow for quick and adjustable control of torque and braking force.
- Robotics: Tunable dampers for precise control, ER fluids help robots adjust movement smoothly and accurately.
Thermoelectric Materials
Thermoelectricity
Thermoelectric materials generate electricity when heat flows through two different conductors joined together. The temperature difference causes an electric current to form.
- Stimulus - Temperature difference
- Response - Generates electricity (or causes heating/cooling)
- Power Generation: Waste heat recovery in automobiles and industrial processes.
- Cooling Systems: Solid-state coolers for electronics.
- Wearable Technology: Energy harvesting from body heat.
A smartwatch strap incorporates a material that generates an electric charge when it is bent or flexed, powering its health sensors. What smart material is this describing?
- Shape memory alloy
- Photochromic material
- Piezoelectric material
- Magneto-rheostatic material
Solution
Award 1 mark for correct answer: c - Piezoelectric material
