Application of Micro Sensors on Diagnosis of Micro Fuel Cells

The fuel cell has the potential to become an indispensable source of electric power. However, some problems have not yet been resolved. Measuring the temperature and humidity inside the fuel cells is currently difficult. Accordingly, in this study, array micro sensors are fabricated within the fuel cell, in which the temperature and humidity distributions are measured. The substrate of the bipolar plate of the fuel cell was made of stainless steel (SS-304) and the wet etching was employed to fabricate the channel on the stainless steel substrate. Then microelectromechanical systems (MEMS) technology was used to fabricate the array micro temperature sensors and the micro humidity sensors on the rib of channel of stainless steel. The advantages of array micro temperature sensors are their small volume, their high accuracy, their short response time, the simplicity of their fabrication, their mass production and their ability to measure the temperature at a precise location more effectively than the traditional thermocouple. The micro humidity sensors are made from gold and titanium as down and up electrodes in the channel. The performance curves of the single cell operating at 41.54 degC and gas flow rates of H₂/O₂ at 200/200ml/min. The max power density of the bipolar without micro sensor is 142 mW/cm² and the current density is 463 mA/cm². The max power density of the bipolar with micro sensor is 56 mW/cm².