Multi-scale Photonic Crystal Enhanced Core-Shell Plasmonic Nanomaterial for Rapid Vapor-Phase Detection of Explosives

Surface-enhanced Raman scattering (SERS) has started to attract more attention in vapor sensing; however, practical applications require shorter response time and better sensitivity. Herein, we report a facile multi-scale SERS substrate for trace-level detection of vapors using a portable Raman spectrometer through the synergistic integration of biologically fabricated diatom photonic crystals and gold-silica core-shell nanoparticles. The multi-scale substrate is composed of (1) a micron-scaled, 3-dimensional, diatom biosilica frustule enabling efficient vapor-substrate interaction for rapid sensing, (2) periodic pores, on the order of 100 nanometers, inducing plasmonic-photonic coupled resonances for enhanced SERS signals, (3) gold nanoparticle cores, with a diameter on the order of 10 nanometers, contributing plasmonic field enhancements, and (4) porous 1 nanometer-thick silica core-shells enabling analyte vapor adsorption and concentration. The combination of the hierarchal, multi-scale features result...