Patent ID: 7220513

Claim:
A fuel cell comprising: a separator plate including a flow field; a membrane electrode assembly having an active area formed on a proton exchange membrane; and a gas diffusion medium interposed between said separator plate and said membrane electrode assembly such that said active area is in reactive interface with said flow field, said gas diffusion medium including: a hydrophobic layer formed adjacent said separator plate and in fluid communication with said flow field; a hydrophilic layer formed adjacent said membrane electrode assembly and in fluid communication with said membrane electrode assembly; and at least one capillary element extending through said hydrophobic layer and terminating inside said hydrophilic layer; wherein at least one of said hydrophobic layer or said hydrophilic layer is variable as applied across the gas diffusion medium, wherein a reactant gas is transported in said reactant flow field and distributed to said active area through said gas diffusion media.