Quality membrane electrode assemblies

To build an efficient, high-quality microscale fuel cell, microfabrication techniques need to be combined with appropriate materials such as Nation based membrane electrode assemblies (MEAs). These techniques must be able to produce three-dimensional structures, allow reactant and product flow into and out of the device, process appropriate materials, and should be of low cost. Fortimately, traditional thin film techniques can be modified for microscale fuel cell fabrication, while maintaining their advantages of surface preparation, sensor integration, and finishing or packaging. In addition, other techniques are also available and are discussed in the following sections. 

A membrane electrode assembly (MEA), where the fuel cell anode and cathode halfreactions occur, is the heart and the most delicate part of a fuel cell system. The performance, stability, and durability of a fuel cell largely depend on the quality of the MEAs. Therefore, MEA qualification should be critical in developing durable, high performanee fuel eell systems. 

Usual enzyme electrodes are assemblies of several membranes placed one on top of the other. The sensitive enzyme membrane is mostly mechanically stabilized by a thin, enzyme-free dialysis membrane. Whether this arrangement is taken into account or neglected in favor of simplicity affects the quality of the model to a major extent. In sensors using more than one enzyme, the enzymes may be coimmobilized in one membrane or applied as immobilized layers in separate, sandwiched membranes. The respective models are different. 

This process is usually performed for manufacturing of single MEAs discontinuous. Via the GDE process, the pre-manufactured catalyst-loaded gas diffusion electrode loaded with catalyst is pressed together with a polymer electrolyte membrane to form an MEA. The doping procedure can take place on the membrane or the electrode. This process is widely used due to the fact that the polymeric membrane is not stressed as much as in the other manufacturing techniques. Less beneficial, here the production and assembling costs have to be mentioned. Every component has to get manufactured, cut, and assembled separately. But this lead to excellent possibilities to exclude material with low quality early. 

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