fig8

Figure 8. (A) Schematic of a dual-function hydrogel optical fiber (HOF) sensor. The fiber features a step-index core-cladding structure doped with phenol red, enabling simultaneous monitoring of sweat pH and joint motion. Reproduced with permission^[120]. Copyright 2024, American Chemical Society; (B) Diagram of a reflective tapered optical fiber sensor for SERS-based lactate analysis. The fiber tip is chemically etched and decorated with Ag NPs to create high-density hotspots for rapid and sensitive Raman detection. Reproduced with permission^[121]. Copyright 2025, Elsevier; (C) Illustration of a fiber optic SPR biosensor for cholesterol detection. The sensing probe is fabricated via electroless silver plating on the fiber core and functionalized with cholesterol oxidase for specific enzymatic recognition. Reproduced with permission^[116]. Copyright 2025, Elsevier. APTES: (3-aminopropyl)triethoxysilane; β-CD: β-cyclodextrin; CHOL: cholesterol; SPR: surface plasmon resonance; EDC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide; NHS: N-hydroxysuccinimide; SERS: surface-enhanced Raman scattering.