LAUSR

High-aspect ratio Si pillar arrays are attractive options for chemical and biological sensors owing to their high surface area in comparison to their planar counterparts. In addition to easy production of threedimensional (3D) structures via established microfabrication techniques, Si micropillars can further be tailored to desirable nanostructures for enhanced optical sensing at their interfaces in a media of interest (e.g., liquid, gas). In this work, we describe the fabrication of Si micropillar arrays via metal-assisted chemical etching (MACE) processes and show an optical enhancement at their Si shell in a fluorescence oil environment. The hyperspectral photoluminescence (PL) images collected with a 405 nm laser beam illumination suggest an unexpected PL emission at 500 nm can be attributed to a strong light-matter interaction at the interface of nanostructured Si pillars and fluorescence oil.