Preparation And Research Of Capacitive Sensor Based Silicone/Carbon Nano-tube Composite Conductive Film

With wearable electric smart textiles appearing, textiles and clothing not only can satisfy the basic wear requirements, such as warm, decoration and so on, but also exhibit more functions, such as perception and feedback, response and self-diagnosis, self-healing and so on. The electric smart textiles with these functions can promptly convert the perceived physiological and environmental signals into detectable electrical signals. For the ideal electric smart textiles, the basic features with flexibility and comfort and intelligence features both are important. Therefore, our researches focus on flexible and capacitive sensor with intelligence features.Based on previous studies, we obtain the conductive and flexile organic films by filling silicone rubber(PDMS) polymer particles into treated carbon nano-tubes. With the film we designed a capacitive sensor and measure the capacitance value which is verified by ANSYS software. Finally the relationship between forces and capacitance is achieved by applying outside force and measuring the capacitance value, which can provide some theoretical references for designing capacitive sensor applications with smart features.The results are as follows:(1) After treating carbon nano-tubes by nitric acid and KH-570, the impurities in carbon nano-tubes are removed. Also some entangled positions are stretched and some defects on the end of carbon nano-tubes are presented. These changes improve thermal properties of carbon nano-tubes and prompt carbon nano-tubes are more easily dispersed in the matrix.(2) Modified carbon nano-tubes are equably dispersed in silicone rubber matrix and exhibit better conductive than untreated carbon nano-tubes composite film prepared. When 3% carbon nano-tubes are dispersed in silicone rubber matrix, a better mechanical property is showed.(3) We designed a capacitive sensor and measure the capacitance value with self-design circuit. The rationality of the design is certified by comparing measurement results and simulation results of capacitance which show us a very close capacitance value.(4) The relationship between force and capacitance which is achieved by applying outside force and measuring the capacitance value is non-linear. The capacitance value is no longer changing when the pressure reaches 30 m N. And the best sensitivity is 40.5% in the range of 10-20 m N.