Multi-layer concentric ring differential capacitance displacement sensor

Abstract

The capacitance displacement sensor has the characteristics of high precision, low power consumption, good dynamic performance, etc. In view of the existence of contradictions between measurement accuracy and measurement range of capacitance displacement sensor, a new sensor probe was designed, which could increase the positive area of the capacitor plate greatly through the multi-layer concentric ring and differential structure under the same volume. The range and measurement accuracy of sensor can be improved effectively, and the miniaturization of the probe also could be achieved. The high-precision integrated circuit chip CAV444 was used in signal processing circuit, the interference of parasitic capacitance is reduced, and the measurement accuracy is improved effectively through the differential amplifier circuit. Through experimental testing, the developed capacitance displacement sensor has a range of 0.025–1.45 mm, the sensitivity is 0.0572 V/μm, the nonlinearity error is less than 0.8%, the hysteresis error is less than 1.5%, and the repeatability error is less than 0.68%.