A pressure sensor device attachable to a pressure port of a fluid-containing enclosure for measuring pressure of a fluid, the pressure sensor device comprising: a pressure port mounting frame the mounting frame having an interior side for facing the fluid-containing enclosure, the mounting frame having an exterior side for facing away from the fluid-containing enclosure, the mounting frame defining an opening that extends from the interior side to the exterior side, the mounting frame having a sidewall on the interior side; a tube, the tube defining a fluid conduit extending completely through the tube, the tube positioned such that the fluid conduit and a surface area of the tube, through which the fluid conduit exits, are accessible from the exterior side of the mounting frame; and an hermetic seal formed by compressively sealing the tube to the portion of the interior side of the mounting frame, characterised in that the pressure sensor device further comprises: a microelectromechanical system (MEMS) sensor sealed to the tube at a surface area of the tube such that when the fluid conduit is filled with fluid from the fluid-containing enclosure, the fluid presses against the MEMS sensor; and a rigid seal disposed between a portion of the MEMS sensor and a portion of the tube adjacent to the MEMS sensor, wherein the rigid seal has an opening such that the fluid contacts a portion of the MEMS sensor and the rigid seal prevents fluid from exiting the pressure sensor, wherein the tube has a first coefficient of thermal expansion, the MEMS sensor has a second coefficient of thermal expansion, and the rigid seal has a third coefficient of thermal expansion, and wherein the first, second and third coefficients of thermal expansion are within about 0.75 ppm/K of each other. a pressure port mounting frame the mounting frame having an interior side for facing the fluid-containing enclosure, the mounting frame having an exterior side for facing away from the fluid-containing enclosure, the mounting frame defining an opening that extends from the interior side to the exterior side, the mounting frame having a sidewall on the interior side; a tube, the tube defining a fluid conduit extending completely through the tube, the tube positioned such that the fluid conduit and a surface area of the tube, through which the fluid conduit exits, are accessible from the exterior side of the mounting frame; and an hermetic seal formed by compressively sealing the tube to the portion of the interior side of the mounting frame, characterised in that the pressure sensor device further comprises: a microelectromechanical system (MEMS) sensor sealed to the tube at a surface area of the tube such that when the fluid conduit is filled with fluid from the fluid-containing enclosure, the fluid presses against the MEMS sensor; and a rigid seal disposed between a portion of the MEMS sensor and a portion of the tube adjacent to the MEMS sensor, wherein the rigid seal has an opening such that the fluid contacts a portion of the MEMS sensor and the rigid seal prevents fluid from exiting the pressure sensor, a microelectromechanical system (MEMS) sensor sealed to the tube at a surface area of the tube such that when the fluid conduit is filled with fluid from the fluid-containing enclosure, the fluid presses against the MEMS sensor; and a rigid seal disposed between a portion of the MEMS sensor and a portion of the tube adjacent to the MEMS sensor, wherein the rigid seal has an opening such that the fluid contacts a portion of the MEMS sensor and the rigid seal prevents fluid from exiting the pressure sensor, wherein the tube has a first coefficient of thermal expansion, the MEMS sensor has a second coefficient of thermal expansion, and the rigid seal has a third coefficient of thermal expansion, and wherein the first, second and third coefficients of thermal expansion are within about 0.75 ppm/K of each other.