The design and fabrication for a novel silicon-based micro direct methanol fuel cell (μ-DMFC) of 0.64cm2 active area on <100> silicon wafer are described in this paper. The novelty of the DMFC structure is that the anodic micro channels arranged in the asymmetric mesh have been fabricated, and the first objective of the experimental trials is to verify the feasibility of the novel structure on the basis of MEMS technology. The effect of different operating parameters on μ-DMFC performances is experimentally studied for two different flow field configurations (grid and spiral). Preliminary testing results show that this novel μ-DMFC demonstrates the better performances using 2M methanol feed at room
temperature, and the output characteristics of μ-DMFC with the grid flow field exceed the one with the spiral flow field. Results have demonstrated a maximum output power density of about 2.3mW/cm2 using 2M methanol solution.
The microfabrication and performance of a micro direct methanol fuel cell (μDMFC) by silicon processes are presented in this paper. Using the silicon micromachining techniques, including thermal oxidation, optical lithography, wet etching, silicon anodization, physical vapor deposition, electroless plating, laser beams cauterization, and anodic bonding, we have successfully made single μDMFC as small as 10mmx8mmx3mm. The main reason for the use of MEMS technology is the prospective potential for miniaturization and economical mass production of micro direct methanol fuel cells. The double side of silicon wafer deep wet etching was employed for the gas channels and fuel chamber preparation. The formation of porous silicon (PS) layers for electrode supports by electrochemical process is the key technologies to improve the MEMS-based μDMFC. The method of catalyst deposition reported here differs from previous work in the specific method of electroless plating Pt-deposition and platinum with ruthenium (Pt-Ru) co-deposition on the porous silicon substrates. The power density of the single cell reached only 2.5mW/cm2 lower than that single cell with traditional MEA (4.9mW/cm2) at the same operation conditions, but further improved performance of the μDMFC with the electro-catalytic electrodes is expectant. Moreover, using the MEMS technology makes the batch fabrication of μDMFC much easier and can reduce the usage of rare metals.