The present invention relates to gas separation membranes including a metal-based layer having sub-micron scale thicknesses. The metal-based layer can be a palladium alloy supported by ceramic layers such as a silicon oxide layer and a silicon nitride layer. By using MEMS, a series of perforations (holes) can be patterned to allow chemical components to access both sides of the metal-based layer. Heaters and temperature sensing devices can also be patterned on the membrane. The present invention also relates to a portable power generation system at a chemical microreactor comprising the gas separation membrane. The invention is also directed to a method for fabricating a gas separation membrane. Due to the ability to make chemical microreactors of very small sizes, a series of reactors can be used in combination on a silicon surface to produce an integrated gas membrane device.