Devices for sampling gastro-intestinal material are disclosed. In one arrangement a device comprises a capsule body. The capsule body has a sample input valve. A suction mechanism is provided that is capable of generating a partial vacuum within the capsule body and thereby drawing gastro-intestinal material into the capsule body through the sample input valve. An actuator actuates the suction mechanism. The actuator comprises a dissolvable element and is configured so that the dissolvable element dissolves in a predetermined region of the gastro-intestinal tract and the dissolving of the dissolvable element causes actuation of the suction mechanism. The suction mechanism comprises a biasing member restrained by the dissolvable element prior to actuation of the suction mechanism. The dissolving of the dissolvable element releases the biasing member. The biasing member expands a sample chamber within the capsule body, without any change to the outer shape and size of the capsule body, on release of the biasing member, and thereby generates the partial vacuum within the capsule body.
