摘要
Omnidirectional strain sensors (OSSs) with tunable sensitivity were prepared by laser-induced nanopowder silver/polyimide (Ag/PI) films to produce laser-induced Ag/graphene (LI-Ag/GN) composites. SEM, XRD, XPS, FTIR, and four-point probe instruments were utilized to examine the microstructures, lattice structures, quantitative chemical compositions, molecular structures, and electrical properties of LI-Ag/GN composites. OSS with a surface laser fluence of 28.01 J/cm2 and an Ag nanopowder concentration of 0.8 wt% exhibited excellent sensing performance. After the tensile test with strain ranges of 0–6%, 6–12%, 12–18%, and 18–24%, the gauge factor values of OSSs were 4.03, 5.76, 8.78, and 11.09, respectively. The OSS could withstand strains as high as 24%, demonstrating its excellent flexibility and tensile strength. Moreover, the sensor demonstrated a stability response under 10 stretching and releasing cycles of 1% to 17% strains, quick response/recovery times of 150/200 ms, and a low hysteresis of 4.11%. Furthermore, the sensor showed excellent response stability and durability under 5% and 7% strains for 5000 stretching and releasing cycles. The developed OSS had been utilized to monitor in real-time human joint motion and to detect low- and high-frequency micro-vibrations underwater and in air. In the future, OSSs would have greater potential to monitor structural health or multidirectional monitoring of flexible wearable devices. © 2026 Elsevier B.V.