Design And Sensing Characteristics Research Of Planar Array Capacitive Sensors

The planar array capacitive sensor is a sensor based on the capacitive edge effect.All its electrodes are located on the same plane,and can measure the measured object from a single direction.The cost is low,non-invasive,high efficiency,and broad application prospects.Due to the soft field characteristics of planar array capacitive sensors,the uneven distribution of internal sensitivity,the shape and arrangement of sensor electrodes,and other factors have a great influence on the detection performance of the entire sensor,so it is of great significance to design the sensor.This paper designs the planar array capacitive sensor and conducts in-depth research on its sensing characteristics.Firstly,the working principle and mathematical theory of the planar array capacitive sensor are analyzed.Taking the electrode shield as the axis of symmetry,according to the electrode symmetry type,four different symmetrical planar array capacitive sensors are designed,which are compared with the original sensors in the laboratory.In order to study the physical characteristics of the sensor,all sensors were modeled using finite element analysis software,and the electric potential distribution of the sensor was simulated,the three-dimensional electric potential distribution and electric potential contour distribution of all sensors were studied,and the effect of shielding on the sensor electric field lines is analyzed.Secondly,the sensitivity of the planar array capacitive sensor is studied.The sensitivity model of the sensor is established,the sensitive field of the sensor is divided into layers,the sensitivity of the first,sixth and 20 th layers of each sensor is imaged,and the characteristics of the sensitivity of each layer are analyzed.The evaluation function of the sensor is established,and the evaluation results of each sensor are studied.The results show that the evaluation results of the diagonally symmetric sensors of up,down,left and right are optimal.Finally,in order to study the imaging performance of all sensors,single hole defect experiment,double wafer defect experiment and three wafer defect experiment were designed to allow all sensors to detect three groups of tested defects,and the capacitance values of each sensor were analyzed.The Tikhonov imaging algorithm is used to image the capacitance value,and a comparative analysis of each imaging result is performed.The imaging results show that there are fewer artifacts in the reconstructed image of the diagonally symmetric sensor up,down,left and right,the position of the defect is more accurate,the degree of defect shape is higher,and the image quality is clearer.