To address the non-uniformity of hotspots and large background noise signals in the Raman spectrum of traditional surface-enhanced Raman scattering (SERS) probes, this paper presents a high-sensitivity and high-uniformity D-shaped fiber (DSF) SERS probe. The probe is prepared by transferring monolayer silver nanoparticles (AgNPs) with different particle sizes onto the DSF using a liquid-liquid interface method. The electromagnetic distribution on the DSF SERS probe is analyzed with FDTD (finite difference time domain) Solutions simulation software, and the corresponding theoretical enhancement factors are calculated. The DSF SERS probe decorated by AgNPs with a diameter of 100 nm exhibits the largest electric field value among our prepared samples. The experiments are conducted to compare two collection methods with backward and vertical directions The results show that vertical collection offers better Raman enhancement due to the suppression of background noise of the fiber, with a limit of detection (LOD) of 10 −11 mol/L for Rhodamine 6G (R6G). The experimental analytical enhancement factor (AEF) at 611 cm −1 is 1.7 × 10 9 . Furthermore, the multi-molecular detection performance of the DSF SERS probe is experimentally studied and realized successfully.
Haixia Yu,Yang Chong,Penghao Zhang,Jiaming Ma,Dachao Li
Fiber-based techniques make it possible to implant a miniaturized and flexible surface plasmon resonance (SPR) sensor into the human body for glucose detection. However, the miniaturization of fiber SPR sensors results in low sensitivity compared with traditional prism-type SPR sensors due to limited sensing area. In this paper, we proposed a D-shaped fiber SPR sensor with a composite nanostructure of molybdenum disulfide (MoS 2 )-graphene to improve the sensor sensitivity. Compared with the traditional cylindrical fiber, the planar sensing area on the side-polished fiber makes it easier to modify two-dimensional materials. Chemical vapor deposition (CVD) graphene and CVD MoS 2 were modified on the sensor surface to obtain the MoS 2 -graphene composite nanostructure. π-π stacking interactions were used to modify pyrene-1-boronic acid (PBA) on the graphene. The excellent photoelectric properties of the MoS 2 -graphene composite nanostructure and the ability of PBA to specifically bind glucose molecules improved the glucose detection performance of the SPR sensor. The results show that specific detection of glucose was realized and that the highest sensitivity was achieved with three-layer MoS 2 and monolayer graphene.
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