A FULLY-ENCLOSED MICRO PEM FUEL CELL WITH SELF-REGULATED FUEL DELIVERY AND SHUT-DOWN

Abstract: A fully-integrated, self-regulated micro fuel cell (FC) system is reported to power implanted, under-water, or on-flight devices in anaerobic environments. Using silicon micromachining processes, we have fabricated hydrogen and oxygen generators and demonstrated their capability to automatically deliver reactants to a μFC with self-regulation. Hydrogen gas is generated by catalyzed hydrolysis of an aqueous sodium borohydride solution, while oxygen is generated from a dilute solution of hydrogen peroxide. During normal operation of the μFC, gas bubbles generated by the reactions are employed to circulate the liquid reactants automatically without consuming any electrical power. Once the μFC is shut down, the gases will automatically empty the reaction channels to stop the reactions. The gas generation rate is found to be positively correlated to the fuel cell current output, revealing the self-regulation nature of the system. Repeatable automatic shut down is also demonstrated