A microfluidic cartridge that includes at least one reservoir for storing a reagent or the like for an extended period of time. In one illustrative embodiment, at least part of a wall of a reservoir includes a hydrophobic material, such as a polymonochlorotrifluoroethylene (PCTFE) homopolymer and/or copolymer. The hydrophobic material may help reduce leaching, evaporation, diffusion and/or other transfer of the reagent or one of its components from the reservoir. When the reagent or the like is lyophilized, the hydrophobic material may help keep water, water vapor and/or other gases or liquids from entering the reservoir prior to use of the microfluidic cartridge.