“…These can be categorized by the type (e.g., plastic, single mode, multi-mode, photonic crystal fibers), geometry (e.g., straight, U-shaped, tapered fibers), the sensing mechanism (e.g., evanescence wave absorption, reflection measurement), the area where the MNPs have been immobilized (e.g., tip, side core deposition, cladding deposition), the MNP material (e.g., gold, silver), shape (e.g., spheres, rods, cubes), coatings (e.g., citrate, SiO 2 , polymers), and finally the immobilization method [10][11][12][13][14][15][16][17][18][19][20][21][22]. The selection of the immobilization method, in particular, is essential as it affects the physical characteristics of the immobilized MNPs and, inadvertently, the spectral characteristics of their LSPR extinction spectrum, which, for sensing applications, should be as narrow band as possible.…”