A Microscale Vapor-fed Formic Acid Fuel Cell

A silicon-based microfabricated fuel cell running on formic acid vapor as a fuel has been developed to provide on-chip power for MEMS devices, without using any ancillary devices such as heaters, water management, air pumps, etc. As a demonstration instrument, an integrated silicon-based membrane electrode assembly and fuel evaporative structure was packaged in a plastic package to test the vapor-fed fuel cell concept. Initial results (0.4 V of the open circuit potential (OCP) and 2.3 mW/cm of the peak power density) of the cell indicate that evaporation can potentially serve as a passive fuel delivery method for on-chip proton exchange membrane (PEM) fuel cells. The OCP is currently limited by anode reactions and the power density by both a slow anode catalyst (Pt) and low evaporation rates. Continued improvements will raise the cell potential and power by incorporating higher kinetic catalysts, faster evaporative structures, and lower oxygen crossover in the gas permeability membranes.