| At present,three-dimensional force microcapacitance sensors are mainly used in solid-state engines,flexible robots,medical and other fields to detect changes in small stresses in different directions.However,due to the complexity of the detection environment and the miniaturization of sensors,the accuracy of capacitance detection is becoming higher and higher.Microcapacitors are easily interfered by external electric fields,and stray capacitors are introduced.As a result,conventional three-dimensional fort-capacitance sensors are not suitable for complex environments and can not obtain accurate capacitance values.Therefore,the research of a shielding method based on three-dimensional force microcapacitance sensor is a key problem to be solved in the field of microcapacitance detection.In response to this problem,this thesis proposes a stray capacitance shielding method based on the three-dimensional force microcapacitance sensor by establishing the finite element model of the three-dimensional force microcapacitance sensor.The shielding method analyzes the electric field distribution between the different plates of the capacitive sensor and the influence of the external medium electric field through the finite element simulation of the three-dimensional force microcapacitance sensor model,and realizes the shielding of the stray capacitance through the edge effect principle and the Faraday cage principle.The effect of the shielding method is verified by the actual measurement data of the threedimensional force microcapacitance sensor,and the measurement accuracy of the threedimensional force microcapacitance sensor can be improved.In this paper,a model of a three-dimensional force microcapacitance sensor is first established;then the electric field distribution of the model is simulated and analyzed by Maxwell finite element software,and the interaction between the multi-electrode layouts is studied;then a three-dimensional force microcapacitance sensor is designed and manufactured based on the simulation results The shielding electrode is prepared with a PDMS-based three-dimensional force microcapacitance sensor unit;then the capacitive reactance method and the comparison method are used to detect the external stress of the sensor unit,and the theoretical calculation capacitance value is compared and analyzed,and Faraday is used in the detection result.The cage principle further improves the sensor unit;finally,the capacitive reactance method and the comparison method are used to verify that the improved three-dimensional force microcapacitance sensor can effectively block the stray capacitance and improve the accuracy of external force detection.The research results show that the three-dimensional force microcapacitance sensor unit with shielding effect designed in this paper is a cylinder with a radius of 6mm and a height of4 mm,which can detect positive pressure in the range of 0-40 N and shear force in the range of 0-20 N.The positive pressure repeatability error is 13.6%.Compared with the theoretical calculation value,the maximum measurement accuracy error is 2.99%;the shear force repeatability error is 15.9%.Compared with the theoretical calculation value,the maximum measurement accuracy error is 4.99%.Compared with the unshielded three-dimensional force microcapacitance sensor,the initial capacitance value range error of the threedimensional force microcapacitance sensor with shielding effect is 0.66%,which is reduced by 2.59%;when the capacitance is affected by external interference,the floating capacitance is 1.5f F,which is reduced by 23.5f F.In this paper,the shielding method and structure design of the three-dimensional force microcapacitance sensor can effectively shield the influence of external stray capacitance,so that the capacitance value under normal stress and shear force is linearly related to the external stress.Therefore,the stray capacitance shielding method and sensor unit shielding structure design proposed in this paper can improve the measurement accuracy of the three-dimensional force microcapacitance sensor.The research results of this paper can improve the measurement accuracy of microcapacitance sensors,and are of great significance to the design and detection of microcapacitance sensors.The results can be applied to different complex environments,can avoid external interference,can provide a reference for shielding methods in medical and robotics fields,and provide a reference for future shielding research and development of microcapacitance sensors. |
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