Low-Power Fuel Delivery With Concentration Regulation for Micro Direct Methanol Fuel Cell

Over the past decade, the direct methanol fuel cell (DMFC) has been considered as a potential candidate of power sources for portable electronics due to its high energy density and environmental friendly operation. However, the use of diluted fuel loading and active fuel mixer/pump limits the DMFC´s efficiency and operating time dramatically. The disadvantages become more severe in microscale DMFCs which require high conversion efficiency within a small physical space to meet the strict working specifications. In this paper, a low-power micro fuel supplier with programmable concentration regulation was designed and fabricated by using microelectromechanical system technology. The prototype adopted surface-tension pumping as the primary driving force to deliver fuel at zero power consumption. In addition, a well-arranged microfluidic capillary network was used to regulate the fuel concentration. A pulse-power actuated bubbler switch was embedded in the capillary network to achieve the liquid flow control dynamically and to adjust the fuel concentration for micro-DMFC (μDMFC) reaction. Both electrolysis and thermal bubble actuations were investigated in this paper for their effective operations in the prototype. The advantage of precise and low-power fuel regulation within a compact system volume makes the proposed fuel delivery subsystem a suitable candidate for future on-chip μDMFC development.