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When someone talks about smart materials what do they mean? Smart materials are designed to be functional and undergo changes that are reversible; this flexibility means they can perform an active part in the way a structure or device works. Material “smartness” is determined by how the material responds or adapts to its environment and also by the speed of the response.
What kinds of smart materials are there and what are they used for? Smart materials are classified according to the connection between what stimulates them and how they respond. There are three classifications:
- Energy exchanging smart materials which include light emitting materials, electricity generating materials and others.
- Matter exchanging smart materials which are able to store water and gas or particles.
- Property changing smart materials which include shape memory alloys, colour and optically changing materials and adhesion changing materials. (See article 2 of this series.)
Types of smart materials that are currently in use are shown in the table below .
Now we have looked at the types of smart materials let’s look at how they are used. Smart materials are used in a lot of different ways and have applications in aerospace, the marine environment, the automotive industry and civil enginering. Probably the most easily recognised applications are in medical equipment, computers and other electronic devices.
Many people have smart phones and laptops and televisions incorporating the use of smart materials. These materials are changing how we look at things and people and how we interact with each other and the world around us. The development of OLED (organic light emitting diodes) in which an organic compound is an emissive electroluminescent layer is an exciting development. The organic compound emits light in response to an electric current which creates digital displays. Material science now allows these screens to be flexible in shape .
The use of smart materials in drug delivery and storage is an exciting field of research; scientists working in the area such as those at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) are using metal organic frameworks (MOFs). These are ultra-porous crystals which form multi-dimensional structures with enormous surface areas. One gram of this material can have the surface area of more than three football fields. They can be used as sponges for storing gases such as hydrogen or carbon dioxide. At a nano-particle scale they can act as sieves to purify gases or liquids and can be therefore used for the targeted transport of drugs within the body .
Smart materials are set to be used in more products. Bayer are a global company developing many products containing smart materials. Among these products are new formulations of sun screen that contain film-forming dispersion factor Baycusan® C 1000. This forms a flexible film moving with the skin and giving a non-sticky skin feel. It has a very high sun protection factor (SPF 50+) and also a higher water resistance factor .
As more uses for smart materials are developed, the influence of smart materials will be felt in every little thing, changing our world forever.
 Smart Materials, available from http://academic.uprm.edu/pcaceres/Undergrad/Smart-Alessandra/id18.htm [accessed March 2013].
 OLED information, available from http://www.oled.at/flexible-oled/ [accessed March 2013].
 CSIRO information, available from http://www.csiro.au/Portals/Media/Next-generation-of-smart-materials.aspx [accessed March 2013].
 Bayer information, available from http://press.bayer.com/baynews/baynews.nsf/ID/DB32869A0296AD31C1257B2B0043E5B8?OpenDocument [accessed March 2013].
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