NOVELTY - A fuel cell layer (8) comprises fuel cell(s) (10) in communication with first reactant plenum (12) and second reactant plenum (14), one containing oxidant and the other containing fuel. The fuel cell comprises gas barrier region formed by disposing gas barrier material on a substrate; second region having a first port; an electrolyte region formed by disposition electrolyte material on second region; and fourth region having second port.    USE - The fuel cell layer is used for fabricating fuel cell structure.    ADVANTAGE - The fuel cell layer has high aspect ratio cavities increasing the efficiency of the fuel cell. It also allows increased active area to be included in the same volume i.e. higher density of active area.    DETAILED DESCRIPTION - A fuel cell layer comprises at least one fuel cell in communication with a first reactant plenum and a second reactant plenum, one containing oxidant and the other containing fuel. The fuel cell comprises:    (1) gas barrier region (16) formed by disposing gas barrier material on a substrate;    (2) second region having a first port (24) formed by disposing on the gas barrier: a first gas diffusion electrode (26) having a first perimeter; and first seal disposed around the first perimeter, where the first port communicates with the first gas diffusion electrode and the first reactant plenum;    (3) an electrolyte region (32) formed by disposition electrolyte material on the second region; and    (4) a fourth region having a second port formed by disposing on the electrolyte region: a second gas diffusion electrode having a second perimeter; and a second seal (42) disposed around the second perimeter, where the second port communicates with the second gas diffusion electrode and the second reactant plenum, where the second and fourth regions are in communication with the electrolyte region, and the gas barrier region separates the first reactant plenum from the second reactant plenum.    An INDEPENDENT CLAIM is also included for a method for making a fuel cell layer comprising at least one fuel cell having a first and second reactant plenum, comprising:    (1) forming a gas barrier region by disposing gas barrier material on a substrate;    (2) disposing on the gas barrier, a first gas diffusion electrode having a first perimeter forming a first port for communicating between the first gas diffusion electrode and the first reactant plenum;    (3) disposing a first seal around the first perimeter;    (4) disposing on the second region electrolyte material forming an electrolyte region;    (5) disposing on the electrolyte region a second gas diffusion electrode having a second perimeter and forming a second port for communicating between the second gas diffusion electrode and the second reactant plenum;    (6) disposing a second seal around the second perimeter; and    (7) enabling the second and fourth regions to communicate with the electrolyte region, and using the gas barrier region to separate the first reactant plenum from the second reactant plenum.    DESCRIPTION OF DRAWING(S) - The figure is an exploded perspective of the fuel cell used in the fuel cell layer.    Fuel cell layer (8)    Fuel cell (10)    First reactant plenum (12)    Second reactant plenum (14)    Gas barrier region (16)    First port (24)    First gas diffusion electrode (26)    Electrolyte region (32)    Second seal (42)