method and apparatus for determining deterioration of e . g . lubricating oil by measuring the electrical properties of a polymeric matrix holding charged ionic groups . the dynamic range of the device is increased by creating a local polar environment formed around the charged groups of the polymeric matrix and by exploiting bead shrinkage with increasing degradation . both approaches can be further employed in a single sensor by the use of multiple chambers containing a combination of the above . also , contaminant detection is improved by detecting changes in amplitude and / or frequency of noise output . the sensor can also be used to detect a level of oil for instance in an engine oil pan .