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Revision as of 09:25, 8 May 2006

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:

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.

Thermoresponsive materials, either shape memory alloys or shape memory polymers, are materials that can hold different shapes at various temperatures.

Magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.

pH-sensitive (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 with 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.

See also

• Smart windows
• Smart fluid

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