Facile fabrication of a U-shaped optical fiber LSPR sensor based on gold nanospheres via self-assembly method

Abstract Optical fiber sensor based on localized surface plasmon resonance (LSPR) has the advantages of small size, real-time signal acquisition and long-distance monitoring capability. The distribution of nanoparticles on optical fiber significantly affects the optical fiber LSPR sensing performance. In this work, a robust and effective strategy was proposed to fabricate a U-shaped optical fiber LSPR sensor based on gold nanospheres (Au NSs) with nanogaps. Using the three-phase liquid–liquid interface self-assembly method, the compact Au NSs monolayer can be transferred to the optical fiber non-destructively, allowing one-step assembly to obtain a high-performance U-shaped optical fiber LSPR sensor. Employing this sensor, sucrose solutions with refractive indices of 1.333 ∼ 1.420 were successfully detected with a refractive index sensitivity of 153.0 nm RIU −1 . Furthermore, the distribution of the Au NSs on the optical fiber surface after one and ten immersions in 10 g 100 ml −1 sucrose solution was characterized, indicating that the Au NSs monolayer on the optical fiber has excellent stability. This easy-to-operate and time-saving preparation strategy opens a novel avenue to prepare high-performance optical fiber LSPR sensors.