A Novel Method for onLine Monitoring Engine Oil Quality Based on Tapered Optical Fiber Sensor

This paper introduces a highly sensitive, rapid, and low-cost sensing method for online analysis of engine oil quality and predicts the exact time of oil expiration. The multi-mode optical fiber is tapered with great accuracy in measuring the fresh and expired oil refractive indices in mechanical systems. In this paper, the length and diameter of the tapered area of the fiber are optimized by the chemical etching method in different time periods using 20% (V/V) hydrofluoric acid. The oil acts as the external medium for this sensor, and any changes in quality, particle size, and pollution of the oil will consequently affect optical properties, such as the variation in the optical power output. By comparing the optical powers between fresh and used oil, the exact quality of the oil is predicted.