Fig. 1. Experimental flowchart. (a) Schematic diagram of the preparation process of the fiber SERS probe; (b) real image and SEM image of the fiber SERS probe; (c) schematic diagram of Raman detection

Fig. 2. Characterization of the tapered optical fiber SERS probe. (a₁)(a₂) SEM images; (b) SEM image for EDS analysis; (c) EDS analysis of the element types on the surface of the tapered optical fiber SERS probe; (d₁)(d₂) element distribution; (e₁) statistical results of particle size; (e₂) statistical results of gap size

Fig. 3. Schematic of silver nanoparticle enrichment. (a₁) Stress of nanoparticle; (a₂) schematic diagram of the simulation model; (b₁) temperature field of AuNP; (b₂) 3D velocity field of AuNP; (b₃) 2D velocity field of AuNP; (c₁) temperature field of AgNP; (c₂) 3D velocity field of AgNP; (c₃) 2D velocity field of AgNP

Fig. 4. Simulation of electromagnetic field. (a) Schematic diagram of the tapered optical fiber SERS probe; (b) simulation of electric field intensity at the front end of the fiber; (c) enlarged electric field map at the tip; (d₁) (d₂) electric field intensity from point A to O₁ and B to O₂

Fig. 5. The maximum electric field intensity maps. (a) Different gaps; (b) different diameters; (c) different angles

Fig. 6. Raman measurements. (a) Test results of R6G ; (b) test results of R6G and CV mixture

Fig. 7. Time-sensitive experiments. (a) Results of bimetallic SERS probes; (b) relative results of single Ag and bimetallic SERS probes at 611 cm^-1 with R6G as analyte