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1.2 Definition
To describe the state of the art in intelligent textiles, a general definition of what is understood by
“intelligent” textiles is presupposed. There is no precise definition of the term “intelligent” or “smart”
with reference to textiles. However, in the following we are trying to approach the term in scope of the
aforementioned material.
The essence of intelligence is being able to sense the surrounding and to react upon it.
Intelligent or smart materials are hence able to react upon stimuli from the surrounding.
These stimulating factors can be of various origins, like temperature, light, humidity, electricity, force,
pressure, mechanics, chemicals or magnetism.
The concept of intelligent materials was first defined in Japan in 1989. In the U.S. this kind of materials
are called Smart Materials. The discovery of shape memory materials in the 1960s and intelligent
polymeric gels in the 1970s were however generally accepted as the birth of smart/intelligent
materials.
Shape memory silk yarn was introduced as the first smart textile in Japan in 1979.
It was not before the late nineties that the concept of intelligent textiles was commonly known in the
textile industry. There have been technical textiles, functional textiles and now a new discipline,
intelligent textiles, has arisen.
According to the manner of reaction, intelligent textile materials can be classified into three categories:
passive smart, active smart and very smart.
Passive smart materials can only sense their environment or external stimuli, they are sensors.
Active smart materials sense stimuli from the environment and react to them; they are sensors and
actuators. Very smart materials sense, react and adapt their behaviour to the given circumstances [2].
In principle, a smart textile is the integration of sensors, actuators, computing, such as data
transmission and processing, and power sources into the textile, the whole being part of an interactive
communication network. It is not of necessity for a textile to contain all these five functions.
The change in environmental conditions will cause the material to change instantaneously in form,
colour or structure.
Sometimes, the change in the material is clearly visible, but sometimes it also takes place on a
molecular level, completely invisible to the human eye.
These smart materials are incorporated into the textile structure by different technologies. Among
those are spinning, extruding, weaving, knitting, making a non woven, braiding, embroidering, sewing,
coating, finishing, laminating and printing. The resulting intelligent textile will have self-regulating
properties on the basis of changes that occur in its surrounding [3].
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