Design, Fabrication, and Characterization of a Pt/Au Thin-Film Thermocouple Array

Abstract

Owing to the micro-electro-mechanical system technology, thin-film thermocouple (TFTC) arrays have emerged for real-time temperature mapping. A minimum distance of 2 mm between thermocouple junctions and a junction size of up to 9 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> have been achieved previously. In this study, a self-calibration TFTC array with 24 TFTCs and 16 platinum resistance thermometers (PRTs) on a 22 mm diameter disk is designed based on the electrode-sharing architecture and fabricated using the screen printing technology. The thermoelectric characteristics of the TFTC array are calibrated through a nonstandard method. This involves utilizing laser heating to establish a temperature gradient on the TFTC array and obtaining the temperatures at hot junctions through extrapolation. The calibration reveals consistent results for the on-chip PRTs and TFTC array. The ratio of the standard deviation and mean resistance R at 0 °C for 16 on-chip PRTs is 3.89%, while that for the standard deviation and mean temperature coefficient A is 1.03%. The electromotive force deviations for eight groups of thermocouples are below ±20 μV. This demonstrates the applicability of screen printing technology for fabricating PRTs and TFTCs. Additionally, the low resistance of the on-chip PRT allows for a fast, and low-cost data acquisition system. A data acquisition system is implemented for the calibration experiments, producing a resistance measurement standard deviation of 0.05 mQ in the 0 to 1.5 Ω range.