Detection of cocaine using gravure printed silver nanoparticle based SERS substrate

A surface enhanced Raman spectroscopy (SERS) substrate was developed for the detection of cocaine. The SERS substrate was fabricated by gravure printing a metallic layer of silver nanoparticle (Ag NP) ink, with average particle size of 150 nm, on a flexible and stretchable thermoplastic polyurethane (TPU) substrate. The feasibility of the printed substrate to enhance the Raman spectra of cocaine was investigated. An enhancement factor (EF) of three, in the intensity of Raman spectrum of cocaine on the printed SERS substrate, was observed when compared to target molecules absorbed on bare TPU substrate. This EF is based on the large electromagnetic fields, that are localized at hot spots, created by interaction of the Ag NPs with light. The SERS based response of the printed substrate thus demonstrated the capability of the printed SERS substrate to be used in drug detection applications.