Fabrication and testing of micro PEM fuel cells using glass wafer

Abstract

This thesis describes the fabrication and testing of a micro PEM fuel cell using glass wafer by means of MEMS technology. Micro fuel cells have been recognized as promising electrochemical power sources for applications on portable microelectronic devices due to their safety, high efficiency, renewable fuel and environmental compatibility. In fact, micro fuel cells are expected to attain higher energy density than that of lithium batteries by converting hydrocarbon fuel to electric power at several percentage or higher efficiency [8-9]. Especially, micro PEM fuel cells are good candidates for portable electronics applications due to their low operation temperature, fast response to load variation, and easy refueling. The energy density of the fuel cell system is related with the total weight of the stack; that is, the volume and mass that the stack occupies directly affects the performance(energy density) of the portable system. One of the major components that occupies the mass of the fuel cell stack is the bipolar plates, and mass reduction of this is important. A new material - photosensitive glass - was proposed as the material for bipolar plates of micro PEM fuel cells. The advantages of glass bipolar plates lie in relatively low fabrication cost, easily attainable high aspect ratio micro structure, and high chemical resistivity. Photosensitive glass is a useful material for the production of components for a wide variety of micro systems [10]. Examples are micro solid thrusters, micro fuel cells, or micro hydrogen reformers [10-11]. Compared to conventional graphite, photosensitive glass is non-porous, has high chemical resistivity, and can yield high-aspect ratio micro structures using MEMS technology. In this study, the fabrication process consisting of UV exposure, anisotropic wet etching, thermal bonding, metal deposition, etc. were fully established. Mass production is possible and each step is easily controllable. The micro PEM fuel cell using gl...