An integrated microfluidic self-regulating and self-circulating hydrogen generator for fuel cells

This paper introduces a micro-hydrogen generator with self-circulation and self-regulation mechanisms for delivering alkaline sodium borohydride solution without parasitic power consumption. The self-circulation of the sodium borohydride solution was achieved by using directional growth and selective venting of hydrogen bubbles in microchannels, which leads to agitation and addition of fresh solution without power consumption. The pumping rate can be automatically regulated by the pressure at the gas outlet, which directly corresponds to the current output of the fuel cell, and thus the electrical load. Design, fabrication, and testing results of a prototype system are described. A maximum hydrogen generation rate of 0.5 sccm and self-circulation/self-regulation mechanisms have been demonstrated in this paper.