Fn. Toth et al., A PLANAR CAPACITIVE PRECISION GAUGE FOR LIQUID-LEVEL AND LEAKAGE DETECTION, IEEE transactions on instrumentation and measurement, 46(2), 1997, pp. 644-646
A new capacitive precision liquid-level gauge has been developed, The
sensor consists of a low-cost planar electrode structure, a capacitanc
e-controlled oscillator and a microcontroller, The device is able to m
easure absolute levels of conducting and nonconducting liquids with a
1 mm uncertainty 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 o
f 0.02 mm/h can be detected within 18 min.