Symmetric silicon micro fuel cell with porous electrodes

We have developed a silicon microfabricated PEM fuel cell which uses hydrogen as fuel. The device employs flow channels with dual structure: isotropic plasma etching has been used for defining the large channels and gas conduits, and anisotropic plasma etching under passivating conditions (high concentration of oxygen in SF 6 ) has been used to create silicon nanograss (black silicon) to increase surface area and triple junction points. The design presented here achieves the following goals: simple and cheap to fabricate, high power density (45 mW/cm 2 ), longevity and integrability.