Highly sensitive fibre surface-enhanced Raman scattering probes fabricated using laser-induced self-assembly in a meniscus

Abstract

Fibre surface-enhanced Raman scattering (SERS) probes have the advantages of flexibility, compactness, remote sensing capability and good repeatability in SERS detection and thus have a range of different applications. However, it is difficult to realize simple, low-cost and high-throughput preparations of fibre SERS probes with high sensitivity and desirable repeatability using the currently available fabrication techniques, which restricts their practical applications. We report here a simple, low-cost method using laser-induced self-assembly to realize the fast fabrication of fibre SERS probes with high sensitivity and excellent reproducibility. By lifting the fibre facet above a pre-synthesized nanoparticle colloid, a meniscus can be formed with the help of the surface tension of the liquid. Using irradiation from an induced laser guided by the fibre, localized thermal effects on the nanoparticles in the meniscus control the growth of the fibre probes and the electromagnetic interactions among the closely spaced nanoparticles assist the arrangement of nanoparticle clusters on the fibre facet. The prepared fibre probes showed a very high SERS sensitivity of 10⁻¹⁰ M for p-aminothiophenol using a portable commericial Raman spectrometer with a short integration time of 2 s. They also showed excellent repeatability with relative standard deviations <2.8% in the SERS peak intensities for different detections with the same probe and 7.8% for different fibre probes fabricated under the same conditions.