Smart material
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Smart materials are materials that have one or more properties that can be significantly altered in a controlled fashion by external stimuli, such as stress, temperature, moisture, pH, electric or magnetic fields.
There are a number of types of smart material, some of which are already common. Some examples are as following:
- Piezoelectric materials are materials that produce a voltage when stress is applied. Since this effect also applies in the reverse manner, a voltage across the sample will produce stress within the sample. Suitably designed structures made from these materials can therefore be made that bend, expand or contract when a voltage is applied.
- Shape memory alloys and shape memory polymers are Thermoresponsive materials where deformation can be induced and recovered through temperature changes.
- Magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.
- pH-sensitive polymers are materials which swell/collapse when the pH of the surrounding media changes.
- Halochromic materials are commonly materials that change their colour as a result of changing acidity. One suggested application is for paints that can change colour to indicate corrosion in the metal underneath them.
- Chromogenic systems change colour in response to electrical, optical or thermal changes. These include electrochromic materials, which change their colour or opacity on the application of a voltage (e.g. liquid crystal displays), thermochromic materials change in color depending on their temperature, and photochromic materials, which change colour in response to light - for example, light sensitive sunglasses that darken when exposed to bright sunlight.
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