Design of a passive microwave sensor for the characterization of mobile engine oil

We are interested in this work to the design and more particularly the achievement of a passive and inexpensive microwave RFID sensor. This will be allowing us to control and to monitor the quality of the engine oil of a mobile. The sensor consists of a dipole placed inside the oil sump of the mobile. Knowing the variation of the relative permittivity of the engine oil, as a function of the distance travelled, we can detect when the latter is worn and when the emptying operation has to be carried out. The principle of this method consists in going back to the value of the relative permittivity of the engine oil from the variation of the resonant frequency of the dipole. This variation in frequency is directly related to the degradation of the engine oil. Analysis of the results of simulations and measurements showed a good sensitivity of the sensor, depending on the distance travelled.