A new capacitive precision liquid-level sensor

The liquid-level sensor consists of a low-cost planar electrode structure, a capacitance-controlled oscillator and a microcontroller. The sensor is able to measure absolute levels of conducting and non-conducting liquids with a 1 mm accuracy over a 4 m range. The system has a high resolution of 0.1 mm at short measuring times of only 0.2 s. Slow level movements of 0.02 mm/h can be detected within 18 min.