Optofluidic In-Fiber Surface-Enhanced Raman Detection Based on Cloverleaf Hollow Optical Fiber

This article presents a sensor that leverages a cloverleaf hollow fiber (CHF) for optofluidic surface-enhanced Raman scattering (SERS) detection within the fiber. Unlike other microstructured fibers, this design features four air holes, providing a larger contact area between the test liquid and the enhanced substrate at the fiber core, which simplifies liquid injection. By taking advantage of this unique structure, silver nanoparticles were modified inside the fiber to serve as the Raman enhancement substrate. The Raman signals are excited via the evanescent field, enabling highly sensitive SERS detection. Rhodamine 6G (R6G) was used as the target analyte, achieving a detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{11}}$ </tex-math></inline-formula> M, an enhancement factor (EF) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.59\times 10^{{8}}$ </tex-math></inline-formula>, and a relative standard deviation (RSD) of 4.8%, demonstrating both high sensitivity and reproducibility in fiber-based detection. Additionally, SERS detection of enrofloxacin solution was carried out, further validating the fiber’s capability in detecting antibiotic substances with excellent stability. The successful detection achieved with this fiber underscores its significant potential for applications in biomedical, agricultural, food safety, and environmental monitoring.