Three-Dimensional Printing of Platinum-Rhodium High-Temperature Thick Film Strain Gauge

Designing high-temperature strain gauges based on in situ strain monitoring is critical for hot-end component health monitoring. However, most current thin or thick film strain gauges (TFSGs) prepared by direct ink writing (DIW) three-dimensional (3-D) printing technology have limited operating temperatures. Here, a platinum-rhodium (Pt-Rh) TFSG prepared by DIW that can operate stably at 1100 °C is reported. The sensing performance of the Pt-Rh TFSG was evaluated at room temperature and high temperature. The experiments showed that the prepared TFSG had a resistance drift rate of 0.47%/h at 1100 °C. The metal alloying of Pt and Rh, along with the doping of glass powder, synergistically enhances the high-temperature performance of the Pt-Rh TFSG. The gauge factors (GFs) of the TFSG were calibrated to 2.42 and 1.58 at room temperature and peak temperature, respectively. In addition, its excellent durability was confirmed by conducting 6000 cycles of strain testing. To demonstrate the design freedom provided by DIW, a strain sensitive grid was directly deposited onto a cylindrical substrate using a four-axis printing platform. This approach could bring exciting opportunities for damage-free, small disturbance, and in situ surface strain monitoring of hot-end components.