Table 1.

Familiar SPR sensors and their performances.

Structure	Characteristics	Wavelength	Sensitivity	Reference
Kretschmann configuration
Typical sensor	Au, Ag metal film	400–800 nm	100–300 deg./RIU	[88]
	Ag film, low index prism	1310 nm	500 deg./RIU	[89]
	Au metal film	500–1000 nm	7500 nm/RIU, 10−8 RIU	[90]
Over layer	Au and Si, ZrO2 thin film	632.8 nm	50–230 deg./RIU	[91]
	Ag-Au bimetallic layer	632.8 nm	7.85 × 10−6 RIU	[92]
Nanostructured sensor	Au nano cylindrical array	632 nm	10−7/RIU	[93]
	Au nanorod metamaterial	1200–1300 nm	30,000 nm/RIU	[94]
	M-D mixed grating	633 nm	~120 deg./RIU	[95]
Multichannel sensor	Dual channel, D over-layer	550–1150 nm	5 µg/mL α-DNA	[96]
	Angled polishing prism	500–900 nm	2710, 8500 nm/RIU	[97]
Fiber-Optic SPR sensors
Symmetrical cladding off	Au, Ag metal film	400–650 nm	2000–4500 nm/RIU	[98]
Grating	Cascaded LPG	~1520 nm	−23.45 nm/RIU
Nano-structured sensor	Au metallic grating	900–1600 nm	4000–9800 nm/RIU	[98]
Nano-structured-coupling
Grating coupling	Au surface grating	~600 nm	440 nm/RIU
	Al-Au bimetallic layer	900 nm	187.2 deg./RIU	[99]
Metamaterial-like	Au nano-structured layer	~150 THz (~2000 nm)	588 nm/RIU	[100]
Nanoparticle based sensors
Nano-structure	Single or double-square periodic nanoparticle array	400–950 nm	200–350 nm/RIU	[101]
	Nanoparticle pair, disk pair	500–900 nm	172,434 nm/RIU	[102]
	Unperiodic array	300–700 nm	165 nm/RIU	[103]
	Gold nano-ring array	300–1800 nm	637.3 nm/RIU	[104]
EOT based sensors
	Square nanohole array	600–1000 nm	300 nm/RIU	[88]
	Nanohole array	1520–1570 nm	1110, 1570 nm/RIU	[105]
	Fluoropolymer Substrates	~600 nm	323 nm/RIU	[106]
Interferometer
	Mach-Zehnder type	~1550 nm	250 nm/RIU	[107]
	Two slit interference	877.3 nm	4547 nm/RIU	[108]
Ring resonator
	Disk resonator	~1460 nm	600 nm/RIU
	Triangular resonator	~1555 nm		[109]

Now, we are going to present different applications of SPR biosensors and their current research status.