Model Research And System Design Of Planar Capacitive Sensor Based On Non-Uniform Medium

In nature,many environmental factors will lead to the non-uniform distribution of the permeability coefficient,electrical conductivity,thermal conductivity and other properties of substances in the spatial position,so that the common form of substances is non-uniform medium,so the detection of substances is essentially the detection of nonuniform medium.The commonly used methods in the detection of non-uniform media include high-density electrical method,ground-penetrating radar method,infrared imaging method and acoustic wave method.Due to the complex operation,high cost,poor environmental adaptability and other problems,these methods have certain limitations in the detection of non-uniform media.In recent years,some scholars have applied planar capacitance sensors to the detection of non-uniform media.Compared with the above methods,it has the advantages of non-destructive detection,convenient operation,low cost and strong adaptability,but it has not been applied to the detection of non-uniform media with uneven surface,such as murals detection or underground plant detection.In order to study the properties of the objects to be measured in this kind of non-uniform medium with uneven surface and the influence of the surface uneven part of the non-uniform medium on the objects to be measured in the interior,and to explore the application of planar capacitance sensors in the above scenarios,this thesis carries out the following research work:(1)Using the finite element simulation software COMSOL Multiphysics to model the non-uniform medium and planar capacitance sensor with uneven surface and design simulation experiments.The relationship between the properties of the object measured in the inhomogeneous medium and the capacitance,the relationship between the uneven part of the surface of the inhomogeneous medium and the capacitance,and the influence of the uneven part of the surface on the detection results of the object measured in the inhomogeneous medium are studied.(2)Based on the simulation results,design the planar capacitance sensor,design the hardware circuit and software program of the detection system,complete the PCB design and circuit debugging of the overall detection system,and build the actual test environment and verification platform.(3)According to the simulation experiment designed in this thesis,in the actual test environment,the above detection system is used to test the property changes of the measured objects in the heterogeneous medium,the influence of the uneven part of the surface of the heterogeneous medium on the internal measured objects under the conditions of different plate heights and different plate spacing is tested,and the test data is processed.Compared with the data obtained from the simulation experiment.The test results verify the correctness and scientificity of the simulation experiment,and provide a new method and idea for the planar capacitance sensor to detect the non-uniform medium with uneven surface.