Conductive fibre developments

Dall Acqua et al.45 reported the development of conductive fibres made by cellulose-based fibres embedded with polypyrrole. Several efforts with cotton, viscose, cupro and lyonell have followed. The conductivity is directly related to the amount of polypyrrole, oxidant ratio and fibre structure with significant differences between viscose and lyonell. Polymerisation occurs uniformly inside the fibre bulk, by producing a coherent composite polypyrrole/cellulose. The mechanical and physical properties of cellulose fibres were not significantly modified as they are the best available45. 

The development and much lower cost of new conductive fibres, yams and fabrics, however, suggest that a move away from wires to polymer-based constractions may be imminent. 

For some purposes, good electrical conductivity or resistance to development of electrostatic change is needed in a composite structure. A range of conductive fibres is available for incorporation to satisfy these requirements. These include fine metal fibres, already discussed, but also glass, carbon and other fibres coated or impregnated with conductive material, usually a metal such as aluminium. 

Fibre optic-based flow-through optical biosensors The dramatic advances in fibre optic development in die last decade have promoted construction of sensors where radiation, whether emitted, transmitted or reflected, is conducted fi-om the sample to the detection system. The wide variety of available optical waveguide types (solid rods, hollow cylinders, micro-planar geometries) has been used with varying success in sensor development. 

The initial studies described above were conducted on Raman microspectrometers on extracted human teeth. In order to translate this research from the laboratory bench to the dental chair side, the next step it is to develop dedicated systems for clinical use. A key element to this development is the use of fibre-optic probes to allow measurements in vivo. We recently reported a study in which optical fibres were used for PRS measurements [48], Although not yet fully realized into a dental probe, this study demonstrated the design and feasibility of acquiring parallel- and cross-polarized Raman spectra via a bifurcated optical fibre whose distal terminal has the two fibres aligned vertically for simultaneously collecting spectra from the two polarization channels on a 2D CCD array. Simultaneous data acquisition will allow for more rapid measurement times in vivo. 

McDonald WI (1976) Padiophysiology of conduction in centi al nei-ve fibres. In Visual Evoked Potentials in Man New Developments (Desmedt JE, ed), pp 352—354. Oxford Clai endon Pi ess. 

Conducting polymers have also been prepared as coatings on both natural and synthetic fibres and fabrics. For example, silk and wool [143,144] or nylon [145] have been coated. The Milliken Corporation developed the first commercial process for producing conducting polymer coated fabrics [146]. 

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