“…Many methods have been developed for real time wear debris detection, such as bulk measurement, capacitance, inductance, acoustic, and optical/imaging detection [1,2,3,4,5]. Among these methods [6,7,8,9,10], an inductive sensor is proved to be the most practical method for the following reasons. Inductance detection could differentiate between ferrous and nonferrous debris [11,12], and it is insensitive to air bubbles and water droplets [13,14].…”