In situ measuring of temperature and humidity within the membrane electrode assembly by micro-sensors

Abstract

This study investigated the micro array sensors which were fabricated by micro-electro-mechanical-systems (MEMS) fabrication technology for monitoring the temperature and humidity distributions within the membrane electrode assembly (MEA) of fuel cells. The micro array sensors were embedded in parylene substrate, the sensors were made from chromium and gold. The advantages of micro temperature and humidity sensors are their small volume, which enables them to be placed on MEA with high sensitivity and accuracy. The dimensions of the temperature and humidity sensors are 180 μm × 180 μm and 180μm × 220μm, respectively. The operating conditions involve temperatures from 30 to 100°C and the resistance of temperature sensor varied from 31.685 to 36.798 Ω. The measuring results reveal that the temperature is almost linearly related to the resistance and the accuracy and sensitivity are less than 0.3°C and 2.3×10-3/°C. The humidity sensor showed that the capacitance changed from 12.14 to 15.03 pF, the relative humidity from 25 to 95 % RH, and the accuracy and sensitivity is less than 0.25 % RH and 0.04 pF/% RH.