High-Linearity and High-Stability AgNPs Thin-Film Temperature Sensor and Microcrack Thin-Film Strain Gauge Based on Laser-Assisted Fabrication

Abstract

Real-time monitoring of bearing operational status is critical for mechanical equipment safety. However, integrated temperature-strain sensors often encounter crosstalk between signals, which affects the accuracy and stability of measurements. Achieving precise in situ monitoring of bearing temperature and strain conditions remains a significant technical challenge. Here, highly linear and stable AgNPs thin-film temperature sensors (AgNPs TFTSs) and AgNPs microcrack thin-film strain gauges (AgNPs MTFSGs) are proposed using laser-assisted printing technology, which is capable of accurately acquiring condition parameters of bearing. The printed AgNPs TFTS exhibited a low hysteresis error of 2.6% and a high linearity of 0.999. The microcracks in AgNPs MTFSG were induced by ultraviolet (UV) laser, yielding a significant enhancement of the gauge factor (GF) from 1.03 (baseline) to 3.19. This twofold sensitivity improvement was achieved while maintaining excellent linearity ( ${R}^{{2}}=0.997$ ). In particular, these thin-film sensors exhibited good stability even when applied to bearings. Typically, AgNPs TFTS and AgNPs MTFSG maintained a low-resistance drift rate of 0.012%/h and a repeatability error of 2.1%, respectively, demonstrating broad adaptability. In addition, both AgNPs TFTS and AgNPs MTFSG exhibited excellent dynamic and static response characteristics. This provides a method for the direct in situ fabrication of thin-film sensors with high linearity and high stability on mechanical components, such as gears and bolts.