Table 1.

Major progress in the optical graphene gas sensors based on microfibers.

Year	Sensor Structure	Target Gas	Performance	Reference
2012	Microfiber attached on graphene	Acetone	Sub-ppk sensitivity	[57]
2014	Graphene/gold coated on microfiber for SPR	NH3	1 ppm sensitivity	[92]
2014	Graphene-coated microfiber interferometers	NH3, H2O	Sub-ppm sensitivity Fast response	[46,89]
2016	Reduced GO coated on microfiber Bragg gratings	NO2	500 ppb sensitivity~100% recoverability	[87]
2017	Reduced GO-based optomechanic microresonator	NH3	1 ppb sensitivity five orders dynamic range	[53]
2018	ZnO-functionalized GO coated on a microfiber multimode interferometer	NH3	Sub-ppm sensitivity High selectivity	[91]