Abstract: A power cell and a method for fabricating a power cell including two body portions and a proton exchange membrane (PEM) there between. The body portions each include a reaction chamber for holding an anolyte solution including a photosynthetic organism or a catholyte solution. At least one body portion has an optically transparent window to allow light into the reaction chamber enabling a photosynthetic reaction. A thin metal layer is coated directly on each of first and second surfaces of the PEM and then the two body portions are coupled together with the PEM located there between. Coating the first thin metal layer on the surfaces of the PEM involves coating a thin gold layer onto the surface, covering the gold layer with a layer of photoresist, patterning the photoresist layer through a mask, exposing the photoresist layer to ultraviolet radiation, and removing the unexposed photoresist.