A support for a thin element in an electrically conducting or semi-conducting material, one face of which is intended to be put into contact with a liquid or gas medium, the support has a first part provided with a central through-passage with a longitudinal axis, said passage including at least one first and one second portion with a different diameter connected to each other through a shoulder, said shoulder being intended for supporting said thin element; a second part penetrating into the passage with the end opposite to the one intended to be exposed to the liquid solution, capable of maintaining the thin element on the shoulder; and a seal between the thin element and the shoulder.