A Novel Electrostatic Coupled Fringing Electric Field Sensor and Design of Signal Detection Circuit

A novel oil sensor designed to address the issue of oil monitoring accuracy influenced by the oil medium and temperature utilizes electrostatic induction coupled with a fringing electric field effect. While retaining the advantages of the electrostatic sensor in detecting small nonmetallic debris (such as ceramic debris), the fringing electric field effect is combined with the electrostatic sensor to measure the changes in the dielectric constant within the oil pipeline of the aircraft engine. Then, the change in oil temperature can be obtained, which not only enables the synchronous acquisition of multidimensional data but also facilitates the analysis of oil properties. It can also mitigate the impact of changes in oil temperature on monitoring the characteristics of wear debris, thereby improving the sensitivity and accuracy of electrostatic sensors in monitoring wear debris. According to the oil environment requirement of an aeroengine, the structure of the novel sensor is designed, and a signal detection circuit with high-frequency anti-interference characteristics is designed. The feasibility of the designed signal detection circuit is verified by simulation and experiments. The results of the Multisim simulation and experiments show that the designed detection circuit could be stably applied to megahertz (MHz) high-frequency excitation conditions and accurately detect small capacitance changes of the picofarad level. It solves the problems of unstable output and extreme distortion in the general detection circuit.