A sensor (1) comprising: a housing (2) defining an internal volume (3); a movable part (4); detector means (5) for detecting movement of the movable part (4); transfer means (6) passing through a first opening (7) of the housing (2) to control movement of the movable part (4) from a first external zone (8); and first sealing means (9) for opposing the passage of fluid coming from the first external zone (8) towards said internal volume (3). The housing (2) includes a second opening (10) extending between the internal volume (3) and a second external zone (11); and second sealing means (12) between the internal volume (3) and the second external zone (11), the second sealing means being adapted to break so as to allow fluid to pass as soon as a first predetermined pressure difference is exceeded.