Stick-slip-motion-assisted interfacial self-assembly of noble metal nanoparticles on tapered optical fiber surface and its application in SERS detection

Abstract

Tapered optical-fiber SERS probes provide a large SERS interaction area and evanescent-wave-based light-matter interaction, but their SERS detection sensitivity is limited due to the difficulty in preparing noble metal nanoparticle structures with large SERS enhancement factor on tapered optical fiber surfaces. In this work, we successfully prepare novel ring-patterned tapered optical-fiber SERS probes with a self-developed stick–slip-motion-assisted interfacial self-assembly method. Unlike the isolated or random distributions of nanoparticles in traditional tapered-optical-fiber SERS probes, the nanoparticles in our probes are aggregated into several rings on optical fiber cones with the help of laser-induced self-assembly of nanoparticles in a meniscus and subsequent meniscus stick–slip motion during the lifting process. These nanoparticle rings provide numerous SERS hotspots due to the formation of clusters. High SERS detection sensitivities of 2 × 10-10 M for crystal violet and 10-9 M for malachite green and thiram in solution are achieved with our ring-patterned tapered optical-fiber SERS probes, and the detection reproducibility is indicated by RSDs of less than 6% for spectral intensity. This work may provide new insights for the design and preparation of tapered optical-fiber SERS probes with high performances.