An Integrated Inductive-Capacitive Microfluidic Sensor for Detection of Wear Debris in Hydraulic Oil

A lot of important information about the working state of hydraulic components can be reflected by wear debris in hydraulic oil, the detection of debris can prevent hydraulic system failures. Due to the weak ability of inductive pulse sensor to detect non-ferromagnetic metal particles, an integrated wear debris sensor, which includes a capacitive pulse sensor and an inductive pulse sensor, is proposed in this paper. The frequency characteristics of the capacitive sensor were explored through experiments, and optimal detection frequency is 0.5MHz. Capacitive sensor can detect and distinguish between air bubbles and metal debris. Inductive sensor can detect and distinguish ferromagnetic and non-ferromagnetic metal debris. By comparing and analyzing the results of two sensors, the integrated sensor with 300 mu m channel can detect air bubbles larger than 80 mu m, 30-300 mu m iron particles and 45-300 mu m copper particles, and effectively distinguish the properties of particles.