In-situ Measurement of the TCR of Pt for Long-term Stability of Thermal Conductivity Hydrogen Sensor

In this study, we developed an in-situ measurement technique for the temperature coefficient of resistance (TCR) of Pt thin film. Pt thin film was exposed to high temperature in the electric furnace at 400°C to evaluate the sintering time dependence of TCR and specific resistance of Pt. During the long-term sintering of Pt thin films at 400°C, it was confirmed that the TCR of the Pt thin films gradually increased, while the specific resistance gradually decreased. Since the specific resistance of the Pt thin film almost linearly decreased with the increase in TCR, TCR can be deduced by measuring the resistance of the Pt thin film. By using the deduced TCR value, it becomes possible to accurately measure the temperature of the micro-hotplate, thereby maintaining the accuracy of the thermal conductivity gas sensor over a long period.