To acquire the final structure of the sharp tip microneedle for easy penetration of the skin, a deep reactive ion etching (DRIE) approach was used. The SiNPs structure, together with the thin edge of the needle is prone to high-energy ion damage, which will result in structural defects. The needle region thinning previously presented reduces the etching time and prevents damage. Once the entire device is ready, a SiO2-protective layer was deposited using plasma-enhanced chemical vapor deposition (PECVD). The silica layer with a thickness of approximately 20 µm was fabricated as a 150 µm X 120 µm pool. Energy-dispersive X-ray spectroscopy (EDS) analysis of the compounds on the surface of the needle is presented in Figure showing the silicon oxide window around the SiNPs sensing area.