Chemistry Reference
In-Depth Information
other gel materials, and the actuating process is not seriously affected
by disturbing electrochemical reactions, mainly because of the relatively
small potential difference that needs to be applied
17
.
•
Non-ionic polymer gel, swollen with dielectric solvent, can be extremely
deformed as is the case for non-ionic polymer plasticised with non-ionic
plasticiser. Instead of the 'charge-injected solvent drag' as a mechanism
of the gel actuation, the principle is based on local asymmetrical charge
distribution at the surface of the gel
18
.The mechanism can also be
applied to non-ionic elastomers in which the motion of the polymer
chain is relatively free. In spite of their many difficulties for practical
actuators, polyelectrolyte gels and related materials are the most inter-
esting electroactive polymer materials.
8.3
Intelligent/smart textiles
8.3.1
Introduction
Advances in polymer and fibre science and in the manufacturing technolo-
gies of fibres, yarns and fabrics have been the driving force behind the
development of smart textiles and innovative products that fulfil customer
expectations. In contrast with the situation that existed 20 years ago, these
products now find applications primarily in sectors outside the textile field.
Therefore, fibre, yarn and clothing producers are in constant pursuit of
developing new materials in order to meet the demands for both traditional
and technical textiles to be used for applications outside the textile
industry.
Smart textiles can be divided into three categories, based on their reac-
tion to the environment:
•
passive smart textiles
can only sense the environmental conditions or
stimuli.
•
active smart textiles
can sense the stimuli from the environment and also
react to these stimuli.
•
very smart textiles
can sense and react to the environmental conditions
in such a way that their reaction is an adaptation to the environment
3,19
.
8.3.2
Fibre-optic sensors, a passive smart textile
Optical-fibre grating (OFG) sensors respond to stain and temperature by
a shift in their optical wavelength. Many optical-fibre grating sensors can
be manufactured onto a single optical fibre, and then analysed indepen-
dently to provide distributed measurements over large structures such as
civil infrastructure. The technology of optical-fibre grating sensors is clas-
sified in three groups, based on the measurement principle:
