A planar micro-reagent cartridge comprising: - a base layer having a fluid receiving cavity formed in a top surface thereof and a fluid disposed within the cavity; - an intermediate membrane layer bonded to the base layer to seal the fluid receiving cavity and form a fluid reservoir pump chamber, the intermediate layer comprising a resiliently deformable flexible region that overlies the fluid receiving cavity and is configured to be depressed in response to application of pressure; and - a top layer bonded to the intermediate layer, the top layer having an opening that exposes the resiliently deformable flexible region of the intermediate membrane layer characterised in that - the intermediate membrane layer further comprises a rupturable valve region that overlies the fluid receiving cavity, the rupturable valve region being configured to rupture in response to depression of the deformable flexible region, wherein the rupturable valve region comprises a single use valve that once ruptured cannot be re-used; - the top layer comprises at least one channel that together with the intermediate membrane layer forms a fluid conduit comprising a capillary channel having an inlet in fluid communication with the rupturable valve region of the intermediate layer and an outlet in fluid communication with a reaction chamber or a fluid outlet formed in a top of the top layer, wherein the deformable flexible region of the intermediate membrane comprises an area of the membrane that is recessed compared to the rest of the membrane layer and has a thickness that is less than the intermediate layer to provide a region of the layer of increased deformability and depression of the deformable flexible region is configured to actuate the fluid reservoir pump chamber to rupture the rupturable valve region and pump fluid into the fluid conduit; - the cartridge having a thickness of less than 30mm, 20mm or 10mm. - a base layer having a fluid receiving cavity formed in a top surface thereof and a fluid disposed within the cavity; - an intermediate membrane layer bonded to the base layer to seal the fluid receiving cavity and form a fluid reservoir pump chamber, the intermediate layer comprising a resiliently deformable flexible region that overlies the fluid receiving cavity and is configured to be depressed in response to application of pressure; and - a top layer bonded to the intermediate layer, the top layer having an opening that exposes the resiliently deformable flexible region of the intermediate membrane layer characterised in that - the intermediate membrane layer further comprises a rupturable valve region that overlies the fluid receiving cavity, the rupturable valve region being configured to rupture in response to depression of the deformable flexible region, wherein the rupturable valve region comprises a single use valve that once ruptured cannot be re-used; - the top layer comprises at least one channel that together with the intermediate membrane layer forms a fluid conduit comprising a capillary channel having an inlet in fluid communication with the rupturable valve region of the intermediate layer and an outlet in fluid communication with a reaction chamber or a fluid outlet formed in a top of the top layer, wherein the deformable flexible region of the intermediate membrane comprises an area of the membrane that is recessed compared to the rest of the membrane layer and has a thickness that is less than the intermediate layer to provide a region of the layer of increased deformability and depression of the deformable flexible region is configured to actuate the fluid reservoir pump chamber to rupture the rupturable valve region and pump fluid into the fluid conduit; - the cartridge having a thickness of less than 30mm, 20mm or 10mm.