| The dissertation focuses on the fabrication of flexible electrically fibrous assemblies under low-temperature vacuum condition as well as the characteristics of conductive textiles used for smart clothing. A method of chemical vapor deposition is employed to let pyrrole polymerize on various textile substrates. An investigation of effects of oxidant concentration, dopant concentration, evaporation temperature for pyrrole, time period of polymerization as well as their interactive effect on electrical performance and sensing performance has been studied. With the optimized processing parameters explored at the beginning of the investigation, a flexible strain sensor and a flexible variable resistor have been developed. The electrical properties and their stability over a period of time and under different ambient condition are observed. Meanwhile the structural features of substrates are studied in order to develop conductive materials where its resistance has the gradient change properties.It has been found that, firstly different processing parameters of polymerization for fabricating conductive fabrics have significant impact for the electrical properties. With an approach of orthogonal experiment, the optimum processing parameters used for fabrication of conductive fabrics are 0.3mol/L FeCl3,0.033mol/L p-toluenesulfonic, pyrrole evaporation temperature at 65℃, polymerization time for 3 hours. The concentration of FeCl3 has the most significant effect on the electrical properties of the fabric.Secondly, weft knitted fabrics have been selected as the substrates developed for flexible strain sensor. Electrical stability and sensibility are very important characteristics as flexible sensors. The surface resistivity of conductive fabrics is tested and the results show that the conductive fabrics appear quite stable electrical performance for 1 month. When the temperature rises, the surface resistivity of conductive fabrics keeps basically in stable condition with a little decline (0.7%-2.5%). When the relative humidity changes, the experimental results show that there is no considerable change in the surface resistivity (the fluctuation is less than 3%). For testing stimuli responding sensitivity of conductive fabrics, a self-made apparatus including stretching device, data acquisition card and software Labview 8.6 is therefore constructed. The results indicate that the average sensitivity over a period of 38 days is stable.Thirdly,in order to fabricate a flexible variable resistor, the structure of substrates is analyzed. The fabrics with changeable density or with different structure distribution as well as the fabrics with punched holes are studied. The resistance along the fabric with different structural features is measured and it has been found that the three fabrics all show a change in resistance with the change of structure. The research work described in this dissertation has made significant contribution for the further development of flexible electrical components which will be useful for the smart textiles. |
