Patent ID: 8047073

Claim:
A capacitive liquid level detector for detecting a liquid level of a liquid in a receptacle, the liquid being conductive, the detector comprising: a capacitor with a first plate having a fixed size and being insulated from the liquid, and a second plate being the liquid itself, the second plate having a size that varies depending on the liquid level inside the receptacle, wherein a thin film dielectric layer is on a surface of the first plate and located between the first plate and the second plate, a thin film passivation layer is between the dielectric layer and the second plate, the first plate having the thin film dielectric layer on its surface is arranged such that it covers an open part of an outer wall of the receptacle, the first plate having the thin film dielectric layer on its surface is attached to the receptacle by sealing means in order to seal the receptacle against liquid leakage, and the thin film passivation layer is a sputtered SiO 2 , Si 3 N 4 or SiO x N y layer, or a spincoated lacquer layer utilizing chemical resistant photo lithography lacquers.