In this study, copper metals were used to fabricate five different flow field plates with various open ratios using MEMS technology. Five samples were prepared for experiments with rib width varying as 150, 200, 300, 450, and 600 £gm at a fixed channel width (300 £gm). The open ratio of flow field plates was varied from 60.0% to 37.9%. Experiments with different operating parameters of anode/cathode pressure drop, cell operating temperature, and gas backpressure were conducted. Furthermore, a simple lumped capacitance model was used to predict the temperature evolution of the fuel cell system. Then, the optimum flow field design and cell operating parameters were finally found. Based on the aforementioned experiments an optimal open ratio ofunity was found like 49.2%. Further, an optimal open ratio in terms of the net power gain factor (= power gain/power consumption) of 38.7% can be obtained for the cases under study. Durability and reliability for copper bipolar plate were examined for long range tests (each run with at least 5 hours duration for consecutive two months). This strongly suggests that copper sheets can be considered as one of possible candidates for flow field material.

In the study, micro-PEM fuel cells are designed and fabricated in-house through a deep UV lithography SU-8 process and a wet etching technique for perforated holes plates (diameter is 750 £gm) of 50 £gm thickness of pure copper. Measurements of cell performance are performed using the low percentage of the weight concentration (1-10 wt. %) of NaOH solution, Al paper as the source material for hydrogen production, and different open ratios of the perforated plates to determine which best improves cell power density. Experimental results are presented in the form of polarization VI and PI curves under the above operating conditions. The experimental results show cell performance is enhanced by the self-heating, humidifying of hydrogen production, hydrogen internal circulation and accumulated pressure. Finally, the micro-PEM fuel cell system with DC/DC boost converter can generate 4.99 V for use in cellular phone accumulators charging.

Indiana University-Purdue University Indianapolis (IUPUI) / An integrated micro PEM fuel cell system with self-regulated hydrogen generation from ammonia borane is reported to power portable electronics. Hydrogen is generated via catalytic hydrolysis reaction of ammonia borane solution in microchannels with nanoporous platinum catalyst electroplated inside the microchannels. The self-regulation of the ammonia borane solution is achieved by using directional growth and selective venting of hydrogen bubbles in microchannels, which leads to agitation and addition of fresh solution without power consumption. The device is fabricated on combination of polystyrene sheets cut by graphic cutter, a stainless steel layer cut using wire electrical discharge machining and bonding layers with double-sided polyimide tape. Due to the seamless bonding between the hydrogen generator and the micro fuel cell, the dead volume in the gas connection loops can be significantly reduced and the response time of self-regulation is reduced.