The SiNPs was fabricated by the deposition of a monolayer of polystyrene beads, 500 nm in diameter, using a spin-coater on the silicon wafer to use as an etching mask for the MACE reaction. In order to reduce the diameter of the beads down to 300 nm, to create a beads array with an inter-distance of 200 nm they were subjected to oxygen plasma etching. The beads were deposited with 45nm of metal silver as a catalyst for the etching reaction while the sensing area was fabricated using standard UV lithography, wet etchers, and oxygen plasma. The vertical SiNPs array is formed using the silver catalyst and HF/H2O2 mixture as the etchant and oxidating agent, respectively. The final SiNPs array consists of tens of thousands of pillars with heights ranging from 5-15µm, Figure depicts a focused ion beam (FIB) cross-section of the fabricated SiNPs after spattering.