Metallic wear particles detection in micro-channel based on resistance signal

It is important to monitor and diagnose the working condition of hydraulic equipment in civil industry. The metallic wear particles in hydraulic oil can cause faults of hydraulic system, so it is crucial to check the wear particles in hydraulic oil. Based on electromagnetism theory and resistance measurement principle, a new oil detection chip has been designed. The main detection area of the chip is consisted of a series resonant circuit. The chip has an advantage of achieving the distinction of metallic wear particles by resistance signal measuring, and current detection chip cannot distinguish metallic wear particles by resistance signal measuring. With theoretical derivation and experiment results, the relation between different metallic particles and resistance signal variation was analyzed. The results indicated that when ferromagnetic wear particles pass through the detection area, the resistance signal is positive. And when non-ferromagnetic wear particles pass through the detection area, the resistance signal is negative. By contrast with inductance detection method, the proposed chip has improved the detecting accuracy. It can detect the iron particles with minimum size of 40ßm and the copper particles with minimum size of 100μm can be detected. This study provides a very good research scheme for oil metallic particles detection.