Influence of Geometric Parameter Design on Performance of Capacitive Proximity Sensors

To deal with the weak signal strength in the measurement of capacitive proximity sensors, the effects of geometric parameter design were investigated, and the sensor measurement performance was greatly improved by the geometric parameter optimization. The comprehensive evaluation standards of sensor performance were presented, including penetration depth, signal strength and noise tolerance, measurement sensitivity and dynamic range. For round capacitive proximity sensors, the effects of the surface area on sensor performance were analyzed. Four different structures including rectangular, round, interdigital and spiral-shaped sensors were designed. In the same conditions, the electric field distributions of the sensors with four structures were simulated and the measured fringe capacitance was compared. The results indicate that the geometric parameters have remarkable influence on the measured signal strength and measurement sensitivity; comparing with rectangular and round sensors, the measurement sensitivity of interdigital and spiral-shaped sesnros was increased by 66.8% and 33.5%.