Research And Application Of Capacitive Sensing On Graphene / Silicone Rubber Based Magnetorheological Elastomers

As a kind of intelligent composite material,traditional magnetorheological elastomers(MRE)have been widely used in various fields such as vibration and sensing.In order to further explore the MRE application feasibility in the field of intelligent sensor,this paper proposes a graphene/silicone rubber based magnetorheological elastomers(GR/RTV MRE),through the simulation and experimental research on the dielectric constant and the compression feature,and further explore the GR/RTV MRE for intermediate dielectric capacitance sensor and the feasibility of the capacitance sensing array.The main contents of this paper are as follows:Firstly,the theory of dielectric constant and compression characteristics of GR/RTV MRE are studied.The dielectric constant calculation model of general MRE was established based on the effective medium theory,and the effect of graphene on the dielectric constant of GR/RTV MRE was analyzed based on the dielectric functional theory.The effects of graphene content and magnetic field strength on the compression properties of GR/RTV MRE are investigated by COMSOL.It provided a theoretical basis for subsequent experimental exploration and application design.Secondly,GR/RTV magnetorheological elastomer samples are prepared.The simulation results showed that the magnetic field intensity met the preparation conditions.The preparation process of GR/RTV MRE is determined.The experimental samples of 0%,1%,2%,3%,4%,5% and 6% of graphene are prepared by in-situ polymerization method.The SEM scanning analysis of the samples showed that the surface of the samples was smooth and the dispersion of graphene and carbonyl iron powder was good,the samples basically met the expected requirements of the experiment.Then,the experiments of dielectric constant and compression characteristics of GR/RTV MRE are completed.The dielectric constants of GR/RTV MRE samples are measured by LCR digital measuring instrument,and the error between the results and the theoretical calculation was less than 7%.A test platform is established to test the effect of graphene volume fraction and magnetic field strength on the compression modulus of MRE.The results showed that under the same magnetic field strength,the compression modulus of GR/RTV MRE increases with the increase of graphene content.Under the same graphene content,the equivalent compression modulus of GR/RTV MRE increased with the increase of magnetic field.Based on the principle of hyperelasticity,the experimental results are analyzed and the stress-strain relationship model is obtained,which provides an experimental basis for the subsequent design of capacitive sensing.Finally,the GR/RTV MRE capacitor sensing and sensor array is designed and the experiment is carried out.Based on the stress-strain relationship model,the capacitive sensing unit is designed.Based on the sensor unit,a micro flexible capacitor sensor array and a small capacitor sensor array are designed,and its data acquisition system is designed.Then,the experiments of the two arrays are carried out.The experimental results showed that the measurement error of each point of the array is less than 1.5%,which can effectively represent the stress state of the flat.