Table 1.

Critical parameters of the refractive index (RI) sensors based on different principles.

Working Principle	Sensitivity	Q Factor	FOM	Detection Limit	Analyte	Reference
PCF	8699 nm/RIU	-	-	4.0 × 10−6 RIU	-	[30]
PCF	1145 nm/RIU	-	-	-	-	[31]
POW	260 nm/RIU	800	-	-	-	[37]
POW	1920 nm/RIU	-	-	5.2 × 10−7 RIU	-	[38]
WGM	1.84 pm/mM	4 × 105	-	0.035 mM	Glucose	[42]
WGM	0.018 pm/mg m−3	11,500	-	6.9 ppm	Benzene	[43]
SPR	-	-	-	1 pM	BSA	[47]
SPR	~104 nm/RIU	-	-	-	-	[49]
FPC	960 nm/RIU	600	18.79	0.01 RIU	-	[53]
FPC	907 nm/RIU	400	9	1.7 × 10−5 RIU	-	[54]