NOVELTY - A fuel cell layer with a central axis comprises unit fuel cells adjacent each other and each comprising front and back process layers, front and back cavities and front and back perimeter barriers. The front cavity is in communication with the front side of the fuel cell. The back cavity is in communication with the back side of the fuel cell. The process layers facilitate an exchange of fuel and oxidants between fuel plenum and oxidant plenum.    USE - As a source of power for an electrical appliance, e.g. airplane, car, laser pointer, cellular phone, wireless phone, projector, television, compact disc (CD) player, radio, flashlight (claimed), DVD player.    ADVANTAGE - The invention provides a fuel cell that allows increased active areas to be included in the same volume, i.e., higher density of active areas.    DETAILED DESCRIPTION - A fuel cell layer (10) with a central axis (11) comprises:    (i) at least a first unit fuel cell (12) and a second unit fuel cell (14) disposed adjacent each other;    (ii) an oxidant plenum (36) comprising an oxidant; and    (iii) a fuel plenum comprising a fuel.    Each unit fuel cell comprises:    (a) a first process layer;    (b) a second process layer;    (c) a first cavity formed between the first and second process layers;    (d) a second cavity formed between the second process layer and a first process layer of an adjacent unit fuel cell;    (e) a first perimeter barrier disposed on the second process layer surrounding the second cavity; and    (f) a second perimeter barrier disposed on the first process layer surrounding the first cavity forming a unit fuel cell comprising a front face (32) and a back face (34).    The first cavity is in communication with the oxidant plenum and the second cavity is in communication with the fuel plenum. At least one of the process layers transports ions between the first and second cavities.    DESCRIPTION OF DRAWING(S) - The figure shows an exploded perspective view of a fuel cell layer, wherein the unit fuel cells are disposed in parallel at an arbitrary angle to the central axis of a fuel cell layer.    Fuel cell layer (10)    Central axis (11)    Unit fuel cells (12, 14, 16, 18, 20)    Front face (32)    Back face (34)    Oxidant plenum (36)    Structure (40)