Low power fuel delivery with programmable concentration control for micro direct methanol fuel cells

The direct methanol fuel cell (DMFC) is considered as a potential power source candidate for portable electronics due to its high power density, efficient and environmental friendly operation. However, the diluted fuel loading and active fuel mixing/pumping limit the DMFC’s efficiency and operating time dramatically. Such disadvantages become more severe in micro-scale DMFCs which require high conversion efficiency and small physical space to meet their strict working specifications. In this paper, a low power micro fuel supplier with programmable fuel concentration control was designed and fabricated using micro-fabrication (or MEMS) technology. The prototype adopted surface tension pumping as the primary driving force to transport fuel in the system without any extra power consumption. In addition, the well designed capillary network was used to ensure the precise fuel concentration regulation. At the same time, a thermal bubble-actuated pulse power switch was embedded in the capillary network and achieved the dynamic fuel concentration control for optimized DMFC operation. The advantages of high power density, precise fuel manipulation, low power fuel concentration control, and compact system size make the prototype a suitable fuel delivery subsystem for micro DMFC development.