Plasmonic-3D photonic crystals microchip for surface enhanced Raman spectroscopy

Plasmonic-dielectic hybrid substrates of Ag-islands on three-dimensional photonic crystals are fabricated through magnetron sputtering of silver onto hydrophobized silica photonic crystals, free from etching process. Without typical hot-spots such as nanogaps, significant Raman enhancements can be achieved, attributed to the enhanced electromagnetic field and scattering of the plasmonic nanoparticles as well as the enhanced light matter interaction by the slow photon effects. The detection limit for adenine by the hybrid substrates reaches nM level, with a calculated enhancement factor of 1.13 x 10(7), which is three orders of magnitude higher than the conventional noble metal film over nanosphere (FON) control group. Furthermore, microchips based on the hybrid substrates are facilely achieved, enabling micro-detection through super hydrophobic concentration. The facile fabrication and effective Raman enhancements make the Ag-islands on 3D photonic crystals promising candidates in the field of chemical sensors, Raman mapping and bioassays.