Design and fabrication of non-contact fringing field capacitive sensor for liquid level measurement

Liquid level measurement is important requirement for building and industrial applications. One of the most popular methods for level measurement is the capacitive sensor. Most of the capacitive sensors are contact type which suffer from frequent maintenance, and drift of the sensor output. Present paper proposes a simple noncontact interdigitated fringing field capacitance sensor for liquid level measurement. Three different interdigitated (IDT) sensors have been designed, simulated (finite element method) and fabricated to measure water level from 0 to 40 mm. The capacitance value of all the three sensors vary almost linearly with the variation of liquid level. Experimental results show that the sensitivity of the 1-5-1 IDT sensor is 0.0398 pF/mm. The sensor is capable to detect water level with resolution of 0.1 mm.