The fuel cell layer with a central axis includes a first and a second unit fuel cell, an oxidant plenum comprising an oxidant; and a fuel plenum comprises a fuel; and each unit fuel cell comprises: a first and second process layer; a first cavity and second cavity formed between the first and second process layer and a first process layer of an adjacent unit fuel cell; a first perimeter barrier disposed on the second process layer substantially surrounding the second cavity; a second perimeter barrier disposed on the first process layer substantially surrounding the first cavity forming a unit fuel cell comprising a front face and back face; the first cavity is in communication with the oxidant plenum; the second cavity is in communication with the fuel plenum; wherein at least one of the process layers transports ions between the first and second cavities.