Thin film temperature sensor for real-time measurement of electrolyte temperature in a polymer electrolyte fuel cell

This paper describes a technique for the measurement of the electrolyte temperature in an operating polymer electrolyte fuel cell (PEFC). A patterned thin film gold thermistor embedded in a 16 mu m thick parylene film was laminated in the Nafion((R)) electrolyte layer for in situ temperature measurements. Experimental results show that the sensor has a linear response of (3.03 +/- 0.09) x 10(-3) degrees C-1 in the 20-100 degrees C temperature range and is robust enough to withstand the electrolyte expansion forces that occur during water uptake. An electrolyte temperature increase of 1.5 degrees C was observed in real-time when operating the fuel cell at 0.2 V and a current density of 0.19 A/cm(2). The temperature sensitivity of the present sensor is in an order of magnitude better than the conventional micro-thermocouples that have been reported. Additionally, use of micro-fabrication techniques allows for an accurate placement of the temperature sensor within the fuel cell. Simulation results show that the sensor has no significant effect on the local temperature distribution. (c) 2005 Elsevier B.V. All rights reserved.