Study On Piezoresistive Properties And Plane Pressure Detection System Of Conductive Silicone Rubber Under Fluid Action

Conductive silicone rubber is a kind of composite materials with special piezoresistive characteristics and temperature characteristics, so it receives more and more attentions. At present, conductive silicone rubber is widely used as the sensing unit element of flexible sensors, its performance directly affects the sensor utility in different applications. At the same time, measuring accuracy and stability of the flexible array sensor is not very high, how to improve the measurement accuracy and stability, and to expand its scope of application has become a problem which need to be solved. This paper describes the mechanisms of conducting and reinforcement. The piezoresistive calculation model of conductive silicon rubber were analysised; Developed a process for preparing the conductive silicone rubber which based on the piezoresistive characteristics.The piezoresistive properties,relaxation properties of the materials under hydrostatic pressure and the surface piezoresistive properties of the material under air pressure were studied respectively. A new type of flexible array plane pressure detecting system was designed.The best ratio of preparing the conductive silicone rubber was determined by comparing the effects of various types of experiments and nature of raw materials. By designing the suitable preparation process and the optimization of the vulcanization molding conditions, such that the internal filler of the conductive silicone rubber could disperse more uniform; Small particle size, high activity carbon black and black /nano-SiO2 (Al2O3) blends was used for reinforcing the composites materials, The results showed that:Shore hardness of the composites could be improved from 35.5HA to 55.5HA, tested comparison found that the preparation process and reinforcing manner could improve the piezoresistive repeatability and stability of the composite material, Thereby indicated that the preparation process and reinforcing method can effectively improve the viscoelastic of conductive silicon rubber and the accuracy of pressure-sensitive materials.The body piezoresistive properties, surface piezoresistive properties, relaxation properties of the materials under hydrostatic pressure and the surface piezoresistive properties of the material under air pressure were studied respectively. Sensitive interval and the relaxation time of different samples were obtained. The results showed that:When under hydrostatic pressure, the body piezoresistive properties of different samples were better than surface piezoresistive properties. Among them, the samples of 6% acetylene black/2% nano-SiO2 blends exhibit the best surface piezoresistive performance, they had the widest pressure-sensitive range, their measure liquid level is 0-20cm; The samples of 6% acetylene black/2% nano-Al2O3 blends exhibit the worst surface piezoresistive performance, they had the narrowest pressure-sensitive range, their measure liquid level is 0-1 Ocm; The piezoresistive properties of adding 8% acetylene black samples are bound to the former two, their measure liquid level is 0-15cm; With the addition of nano-modified materials and the increasement of the materials’thickness (2mm-4mm), the pressure-sensitive interval could be extend and the relaxation time of the conductive silicone rubber could be reduced.The surface piezoresistive properties of conductive silicon rubber when under gas pressure were tested. The results showed that:After adding the modified materials, the piezoresistive curves are superior to the case of adding acetylene black alone when under the air pressure; and with the increasement of the samples’thickness, the piezoresistive properties of the material will have a good upgrade. When the composite materials were at 4mm thickness (in the air pressure range 0.02-0.3MPa), the jet pressure and the resistance value were more clear, but the height of the jet is not conducive to increase the accuracy of pressure sensitive material.Based on the study of various types of conductive silicon rubber properties, selected the appropriate sensitive cell material. Combined with a new type of flexible array structure, through the development of hardware and software, a distributed array pressure detection system was designed. By building and commissioning the system test platform,the real-time data collection capabilities of the plane pressure distribution for two contact surfaces were achieved. By applying different shapes of weight and imaging process, we found that the detection system can not only reduce production costs and be able to achieve pressure distribution in the plane of detection preliminary.