Sensitive Temperature Sensor for a Calorimetric Thermal Voltage Converter

This article presents the design, optimization, and experimental validation of a novel thin-film temperature sensor for a calorimetric thermal voltage converter (CTVC), aiming to achieve high sensitivity and mechanical robustness. Addressing the limitations of existing ac voltage measurement standards and previous CTVC thermocouple designs, this work introduces a sensor fabricated with bismuth and antimony thin films on a 100 µm thick polyimide membrane. A finite element method (FEM)-based optimization, employing a 2.5-D modeling approach and leveraging axial symmetry, significantly reduced computational time while ensuring accuracy in identifying the optimal thermocouple topology. Experimental measurements of the manufactured prototype demonstrate excellent agreement with FEM predictions, yielding an output voltage of 9.3−82.3 mV for 1−3 V input, respectively. A key achievement is the high sensitivity of approximately 0.65 mV/mW, significantly surpassing prior CTVC designs. The design successfully balances mechanical durability and cost-effectiveness with high metrological performance.