A method for forming a surface enhanced Raman spectroscopy (SERS) sensing apparatus may include providing a body having an internal microfluidic passage, the microfluidic passage having an interior surrounded by an interior surface, depositing a conformal inorganic passivation film onto the interior surface so as to continuously surround the interior by atomic layer deposition and positioning a SERS sensor in connection with the microfluidic passage after the depositing of the conformal inorganic film.