How does a Capacitance Level Sensor work?

There are two electrodes which are coupled together and integrated into a high frequency oscillator. When there is no dielectric material (the dielectric material is what is being sensed) the oscillator is tuned to be in the resting state.

As a dielectric material enters the electric field of the sensor, the capacitance increases and oscillation begins. When the amplitude of oscillation reaches a high enough level, a change in signal state is triggered.