What is the role of oxygen sensor

Capacitive sensors are theoretically achievable, but it is more specific trouble, first of all, you have to understand where you want to detect oil, along with the increase of its impurities change characteristics. With the increase in impurities in the oil, as the capacitor dielectric, causing changes in capacitance increase it? Is an impurity, the more the smaller the capacitor? Or more impurities greater the capacitance? How much capacitance or impurities have not changed much? Impurities, the more the greater the density? Impurities, the more the smaller the density? How many little change or impurities? Impurities, the more the greater the turbidity? Impurities smaller, the greater the turbidity? Or how many impurities turbidity change? Through the above analysis, you select one of the parameters for the measurement object, this parameter with the number of impurities were monotonic change obviously. Optional capacitor / density / Camshaft Positioning Sensor. I suggest you buy the above kinds of sensors were put on trial, the effect on the selection of which