Light trapping induced flexible wrinkled nanocone SERS substrate for highly sensitive explosive detection

We fabricate a novel light trapping induced wrinkled nanocone SERS substrate on flexible and transparent PET film for highly sensitive TNT detection based on Meisenheimer complex. [Display omitted] •We report a novel light trapping induced wrinkled nanocone SERS substrate on flexible and transparent PET film.•Highly sensitive TNT detection employed the electromagnetic coupling effect based on Meisenheimer complex.•This flexible substrate can be widely used to detect analytes on irregular or rough surface of the suspicious items. We reported an ultrasensitive TNT detection method via a novel light trapping induced wrinkled nanocone flexible SERS substrate, which was fabricated by colloidal lithography and oxygen plasma etching on transparent PET film. Especially, a set of nanowrinkles with 50−60 nm was found on the sidewall of nanocone after etching. By coating 30 nm gold film, this flexible SERS substrate provided uniform hot spots, which demonstrated high reproducibility and sensitivity. 4-ATP molecules based Meisenheimer complex, which is a well-known charge-transfer interaction between electron-poor TNT and electron-rich amino group, was taken to detect ultra-low concentration of TNT explosive. The Raman signal of TNT was significantly enhanced by charge-transfer, light trapping effect and coupled electromagnetic field. The detection sensitivity of TNT molecules was as low as 10−13mol/L, and show a good linear response in the range from 10−8 to 10−13mol/L. Consequently, by brushing this flexible SERS substrate onto a cloth bag, trace amount of TNT residues with concentration as low as 10-10mol/L can be easily analyzed. It is believed that the proposed highly sensitive and uniform flexible substrate provides a significant solution for trace analysis of TNT residue in criminal forensic, military and security check.