Sick CMB18 Series Capacitive Barrel-Style Capacitive sensor, M18 x 1, 12 mm Detection, PNP Output, 10 → 36 V dc,

Capacitive proximity sensor detect almost any object by non-contact means, regardless of colour, reflection factor, and surface characteristics.

After suitable adjustment of the sensitivity, they even detect objects behind non-metallic walls and can therefore provide a cost effective alternative for level measurement.

-