AgPd Thin-Film Strain Gauges Fabricated by Direct Writing for High-Temperature Application

In-situ strain detection of complex structures at high temperatures remains a challenging task. In this article, the feasibility and performance of silver-palladium (AgPd) high-temperature thin-film strain gauge (TFSG) fabricated by direct ink writing (DIW) based on the Weissenberg effect is investigated, providing an in-situ strain detection method for structures working at high temperatures. The micrometer-thick AgPd film was directly written on a planar alumina substrate, and its surface topography and electrical were characterized. The four-wire resistance measurement method was adopted to eliminate the wire resistance and the contact resistance at the solder joint, thereby improving the accuracy of detection. The strain test at room temperature showed that the gauge factor (GF) of AgPd TFSGs under both tension and compression was about 1.25. They also possessed excellent linearity ( ${R}$ 2 = 0.998), good static and dynamic responses, and extremely low mechanical hysteresis. To verify the high-temperature performance of the AgPd TFSG, the strain dynamic test was carried out at 600 °C. And there was no severe attenuation of the GF. AgPd TFSG fabricated by DIW provides an efficient method for in-situ static and dynamic strain detection of complex structures at high temperatures.