Simple Stacking Methods for Silicon Micro Fuel Cells

We present two simple methods, with parallel and serial gas flows, for the stacking of microfabricated silicon fuel cells with integrated current collectors, flow fields and gas diffusion layers. The gas diffusion layer is implemented using black silicon. In the two stacking methods proposed in this work, the fluidic apertures and gas flow topology are rotationally symmetric and enable us to stack fuel cells without an increase in the number of electrical or fluidic ports or interconnects. Thanks to this simplicity and the structural compactness of each cell, the obtained stacks are very thin (~1.6 mm for a two-cell stack). We have fabricated two-cell stacks with two different gas flow topologies and obtained an open-circuit voltage (OCV) of 1.6 V and a power density of 63 mW·cm, proving the viability of the design.