Development of silver nanorod array based fiber optic probes for SERS detection

The development of intrinsic SERS fiber optic sensors, i.e., fiber optical sensors that also serve as SERS active platforms, is challenging in that an easy, robust method that integrates the SERS active platform with fiber optics is still largely missing. There is a trade-off between implementing optimal morphology of SERS active nanostructures for best enhancement effect and preserving optical transparency that allows maximum transmission of the excitation radiation and the detected signals. In the present work, highly sensitive and reproducible silver nanorod arrays (AgNRs) have been integrated to a fiber optic probe for SERS detection. The films underlying the AgNR coating have been tailored to allow maximum light transmission while maintaining optimal SERS activity. The intense spectral background from the probe fiber core is largely eliminated by using a GRIN lens to produce a tight focus of the incident radiation at the AgNR coating. The performance of the AgNR fiber optic probes has been evaluated in a forward scattering optical configuration using BPE and adenine. The low detection limit of BPE and adenine is 10−7 M. Reproducibility and sampling methods are also discussed.