Abstract
This research is to fabricate μ-DMFC (micro direct methanol fuel cell) by using MEMS technology. A novel concept of design, compared with the traditional type of DMFC, has been designed and fabricated, which anode and cathode are made in the same plane so called coplanar type of DMFC. In this coplanar type of DMFC, we also integrate the current collectors and catalyst layer on the flow channels. In order to conform the three phase theory, we use sulfuric acid as electrolyte which be used to deliver protons. And we pumping air in the cathode fuel make it reach oxygen saturation. In order to improve the performance of entire system, we want to integrate the fuel preheat device on the chip, so heater was put on the flow channels. By this way we don’t use the preheat device which be used to traditional fuel cell, then we can save volume and energy consumption, and increase performance in the same time. Not only the mathematical model was built, but also the experiment data were measured by using developed μ-DMFC. The fabrication of coplanar type μ-DMFC was designed. KOH was used to etch flow channel, then photo resistance was sprayed on the top of flow channels. Lift-off technique was used to define patterns after evaporator deposition. Finally, LASER was used to drill the holes for the inlet/outlet of fuels. Aspect of heater design, we chose Cr metal, 500μm wide and 63mm long (total resistance is 5.2kΩ) zigzag around the flow channel. When the current around 83mA was applied on it, it can reach 85℃ (measure by Thermometer YS-1300K). The fuel (2M CH3OH / 1M H2SO4 / H2O) was fed into anode, and (O2-sat. / 1M H2SO4 / H2O) was fed into cathode, operating under 80℃. The maximum power was reached around 0.992mW/cm2 at 5.16mA/cm2 (measure by DC Electronic Load 3310D series). Even through the power density is quite low compared with traditional DMFC, but it still can be used on specific applications.