Detection of foreign particles in lubrication oil with a microfluidic chip

Abstract

PurposeThe purpose of this paper is to help understand the mathematical model of inductive sensor and to improve the sensitivity of nonferrous metal particle detection.Design/methodology/approachThe expression of impedance change is established, while the distribution regularities of the magnetic field inside and outside the metal particle are obtained based on the Maxwell equations in complex forms, the analytic solution of the electromagnetic field is obtained and the experiment validation is implemented.FindingsThe expression of impedance and the analytic solution of the electromagnetic field are obtained. It is shown that the inductance change is more obvious than resistance change for the iron particles, but for copper particles, resistance change is more obvious and the resistance change increases with the frequency. In this work, copper particles (size: 20 µm) are detected at 2 MHz excitation frequency, and the imaginary part of impedance changes without adding any device, which is provided with a prominent guideline for detection of nonferrous particles of size less than 100 µm.Originality/valueThe expression of impedance change is established, the analytic solution of the electromagnetic field is obtained and copper particles (size: 20 µm) are detected at 2 MHz excitation frequency, and the imaginary part of impedance change without adding any device, which is provided with a prominent guideline for detection of nonferrous particles of size less than 100 µm.