Fabrication of a micromachined direct methanol fuel cell

Small electronic devices require small, compact and lightweight power supplies. Direct methanol fuel cells (DMFCs) offer the potential for double the lifetime of lithium ion batteries. We have designed a process for micromachining direct methanol fuel cells using traditional micromachining techniques and macroassembly. Direct methanol fuel cells oxidize methanol through a catalytic reaction producing carbon dioxide and hydrogen. Hydrogen is further oxidized into hydrogen ions through a second catalytic reaction, producing electrons. We have micromachined flow fields and current collectors for the anode (methanol) side in both <100> and <110> silicon. Using laser ablation, we have opened fluidic channels through the back of the wafer for attaching fluid feed tubes. Aluminum is deposited as a current collector. The fuel cell is assembled using a commercial membrane electrode assembly (MEA), which contains the solid polymer proton exchange membrane (PEM) and catalysts. Sealing is provided using an epoxy. Simulated and actual results are presented.