The data shown below has been collected with the FDC1004EVM. A liquid level sensor with 3 electrodes like the one shown in the schematic was connected to the EVM. The plot shows the capacitance measured by the 3 electrodes at different levels of liquid in the tank. The capacitance of the Reference Liquid (the RF trace in the graph below) and Reference Environmental (the RE trace) sensors have a steady value when the liquid is above their height while the capacitance of the level sensor (Level) increases linearly with the height of the liquid in the tank.

Figure 7-2 Electrode Capacitance vs Liquid Level