Plasmonic-based Raman sensor for ultra-sensitive detection of pharmaceutical waste

Pharmaceutical waste and contaminants pose a significant global concern for water and food safety. The detection of piperidine, a common residue in drug and supplement synthesis, is critical due to its toxic nature to both humans and animals. In this study, we develop a plasmonic-based detector for surface enhanced Raman scattering (SERS) measurements. The plasmonic device is composed of triangular cavities, milled in silver thin film, and protected by a 5 nm SiO₂ layer. Due to the confined and enhanced electromagnetic field, remarkable sensitivity to piperidine with a concentration of 10⁻⁸ M in water is achieved. Despite the relatively small polarizability of piperidine, high sensitivity is observed even when using a low numerical aperture of 0.3, attributed to the directional scattering from our plasmonic device. Thus, it offers a cost-effective alternative to traditional high numerical aperture used in SERS, and the ability to use a portable Raman device for a cheaper and faster analysis.