A portable protective box for a medical flask (22d-22f), the box comprising: a housing; a flask holder encased by the housing and fixed relative to the housing, the flask holder comprising a retainer configured to retain a medical flask (22d; 22e; 22f) in a stationary position relative to the housing; and at least one sensor element (24d; 24e; 24f; 30d; 30e; 30f; 48; 50) having a predefined position relative to the retainer and being configured to enable detection, when the medical flask (22d; 22e; 22f) is retained by the retainer, of at least one of the medical flask (22d; 22e; 22f) being retained by the retainer, a filling level of the medical flask (22d; 22e; 22f), a material of the medical flask (22d; 22e; 22f) and a type of fluid inside the medical flask (22d; 22e; 22f), and characterised in that: wherein the at least one sensor element (24d; 24e; 24f; 30d; 30e; 30f; 48; 50) comprises at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f), wherein the at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f) comprises a first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) and a second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) contacting the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f), wherein the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) is elongated in a first direction of the retainer and the second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) is elongated in a second direction of the retainer different from the first direction. a housing; a flask holder encased by the housing and fixed relative to the housing, the flask holder comprising a retainer configured to retain a medical flask (22d; 22e; 22f) in a stationary position relative to the housing; and at least one sensor element (24d; 24e; 24f; 30d; 30e; 30f; 48; 50) having a predefined position relative to the retainer and being configured to enable detection, when the medical flask (22d; 22e; 22f) is retained by the retainer, of at least one of the medical flask (22d; 22e; 22f) being retained by the retainer, a filling level of the medical flask (22d; 22e; 22f), a material of the medical flask (22d; 22e; 22f) and a type of fluid inside the medical flask (22d; 22e; 22f), and characterised in that: wherein the at least one sensor element (24d; 24e; 24f; 30d; 30e; 30f; 48; 50) comprises at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f), wherein the at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f) comprises a first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) and a second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) contacting the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f), wherein the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) is elongated in a first direction of the retainer and the second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) is elongated in a second direction of the retainer different from the first direction. wherein the at least one sensor element (24d; 24e; 24f; 30d; 30e; 30f; 48; 50) comprises at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f), wherein the at least one capacitance measurement electrode (24d; 24e; 24f; 30d; 30e; 30f) comprises a first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) and a second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) contacting the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f), wherein the first electrode segment (26d; 26e; 26f; 32d; 32e; 32f) is elongated in a first direction of the retainer and the second electrode segment (28d; 28e; 28f; 34d; 34e; 34f) is elongated in a second direction of the retainer different from the first direction.