Study On Piezoresistive Properties And Sensors Of Conductive Silicone Rubber Filled With Carbon Black/Copper Powder

Conductive silicone rubber is a new type of functional material,whose conductivity is generally between the insulator and the metal.Conductive silicone rubber has special piezoresistive property and mechanical property,which can be used for flexible pressure sensor sensitive materials to measure the stress in complex surface.In this paper,carbon black and copper powder were used as conductive filler materials to research the piezoresistive properties of conductive silicone rubber with different content of the two fillers based on theoretical and experimental analysis.The main contents of this paper are as follows:In the aspect of theoretical analysis,firstly,the classical conductive mechanism of conductive rubber was introduced in this article,which included the conductive path theory,tunneling effect theory and field emission theory.Secondly,three kinds of percolation models forming circuits were described.It is concluded that the electrical conductivity of conductive rubber is the result of the combination of various theories.Finally,the piezoresistive model and the formation mechanism of the conductive rubber were analyzed based on conductive path theory and tunneling effect theory,and relaxation characteristic and temperature sensitivity of the conductive rubber was discussed.In the aspect of property research,firstly,the basic property and main application of material required by the preparation of conductive silicone rubber were analyzed in this paper.And the suitable rubber matrix,conductive fillers and auxiliary reagents were chosen.Secondly,the conductivity and piezoresistive property of conductive silicone rubber with different contents of the two fillers were studied.It shows that the addition of copper powder can improve the conductivity of conductive silicone rubber and reduce the content of carbon black when total content remains constant compared with carbon black as single filler.In addition,the study also shows that the piezoresistive property of conductive silicone rubber is related to the content of copper powder.It is concluded that the samples were prepared with the content of 18% carbon black mixed with 8% or 12% copper powder have not only good conductivity,but also a wide range of piezoresistive.Finally,the relaxation phenomenon of the samples at different constant pressures was studied by relaxation experiments,then,the forming mechanism and main influence factors of the relaxation characteristics were analyzed.The result shows that the relaxation time and the relaxation amplitude of the resistivity decrease with the increase of the content of copper powder under constant pressure.In the aspect of sensor design,firstly,this article researched conductive properties of conductive silicone rubber in this article.A flexible array pressure sensor based on piezoresistive effect of conductive silicone rubber was designed and optimized.Secondly,the piezoresistive characteristic of the sensing unit and response time under the continuous pressure were tested by the experiments.The piezoresistive model of the sensing unit was established by using the quadratic curve-fitting method.Finally,the measuring circuit of the flexible array pressure sensor was designed.And the accuracy of the sensor model was tested.Furthermore,the main influencing factors were analyzed.In this actual research,conductive silicon rubber composite prepared by carbon black and copper powder has better conductivity compared with carbon black as a single filler.In addition,the research results of this paper will provide a theoretical basis for the further development of conductive polymer materials and sensors.