Liquid reagents have been stored on both blister packs and in cavities on the chip. For the blister storage concept, the blister pack is formed of a composite-layer film, assembled to the cartridge backbone, filled with the liquid reagent. A small channel connects the blister to the rest of the fluidic network of the cartridge. This channel provides a frangible seal. Once the blister is pressed by the instrument (or manually), this seal opens. With such a concept, a controlled release of the liquid reagent is achieved. The materials used offer protection against environmental conditions (gas exchange) and the reagent is stored without residual air in the blister. Depending on the number of reagents and the volume to be stored, the concept of storing liquid reagents in cavities on the chip can be advantageous. Since most Lab-on-a-Chip platforms are made of polymers, it is essential to use polymers with sufficient barrier properties to allow storage of volatile reagents. Again, the cavities are closed with frangible seals or frangible seal film valves which are opened by the instrument.