NOVELTY - A microfluidic fuel cell package (218) comprises polyimide layers containing resistive heaters, microfluidic channels, anode manifold (204) and a porous membrane, a membrane electrode assembly (MEA) (202) comprising an electrolyte (209), and a cathode manifold (210) comprising microchannels.    USE - The invention is used for, e.g. MEMS-based thin film cells.    ADVANTAGE - The invention creates a tight seal around the periphery of the MEA.    DETAILED DESCRIPTION - A microfluidic fuel cell package comprises:    (1) a first polyimide layer containing resistive heaters;    (2) a second polyimide layer for insulating the resistive heaters;    (3) a third polyimide layer containing microfluidic channels communicating with a fuel source at one end and a fuel feedthrough at the other end;    (4) a fourth polyimide layer comprising an anode manifold containing a fourth layer fuel inlet communicating with the fuel feedthrough, a porous membrane, a fourth layer fuel outlet, where the fourth layer fuel inlet and outlet are configured such that fuel flows horizontally through the fourth layer fuel inlet, then vertically up through the porous membrane, where whatever portion of fuel that does not flow vertically through the porous membrane continues to flow horizontally through the fourth layer fuel outlet;    (5) a fifth polyimide layer for supporting the anode manifold and containing a fifth layer fuel feedthrough communicating with the fourth layer fuel outlet;    (6) an MEA layer containing an MEA, where the MEA comprises an electrolyte sandwiched between an anode and a cathode, the MEA operating at less than 200degreesC, where the anode is positioned such that it is communicating with the porous membrane of the fourth layer, where the fifth layer forms a seal between the porous membrane and the anode;    (7) a sixth polyimide layer for supporting a cathode manifold, where the sixth polyimide layer contains a sixth layer fuel feedthrough communicating with the fifth layer fuel feedthrough; and    (8) a seventh polyimide layer containing a cathode manifold comprising microchannels communicating with the cathode, where the microchannels are used for removing reaction by-products from the cathode, where the sixth layer forms a seal between the cathode manifold and the cathode, and a seventh layer fuel feedthrough communicating with the sixth layer fuel feedthrough; where an electrical feedthrough extends through all the layers of the apparatus to form a bonded polyimide microfluidic fuel cell system.    DESCRIPTION OF DRAWING(S) - The figure shows an expanded view of the microfluidic fuel cell package.    MEA (202)    Anode manifold (204)    Electrolyte (209)    Cathode manifold (210)    Microfluidic fuel cell package (218)