Table 1.

Plasmonic biosensors based on different materials.

Materials		Design	Bio-Analyte	Resonance Mode	Experimental RI Sensing	Enhanced Light-Matter Interactions
Metal	Au	Thin-film: 50 nm (2007) [13]	Rocin	Propagating SPP: 635 nm	Angular Interrogation; LOD: ~3.3 × 10−6 RIU	N/A
		Nanohole array: hole diameter – 200 nm; array period – 450 nm; thickness of Au – 200 nm (2014) [8]	Exosome (50–100 nm); Selectivity: polyethylene glycol (PEG) +monoclonal antibodies	EOT effect: long-wavelength portion in visible regime	Wavelength Interrogation; LOD: ~670 aM	N/A
		Coaxial nanoring aperture array: depth – 50 nm; inner ring diameter – 170 nm; outer ring diameter – 290 nm; array period – 720 nm; thickness of Au – 250 nm (2018) [72]	poly(allylamine)hydrochloride (PAH, 65 kDa); poly(styrenesulfonate) (PSS, 75 kDa)	Modes coupling of dipolar moments from nanohole and nanodisk; long-wavelength portion in visible regime	Wavelength Interrogation; LOD: ~1.4 × 10−4 RIU (estimated)	N/A
		Nanohole array: hole diameter – 200 nm; array period – 600 nm; thickness of Au – 120 nm (2018) [104]	A/G ~ 50 kDa; IgG ~ 150 kDa	EOT effect: long-wavelength portion in visible regime	Phase interrogation; LOD: ~4.5 × 10−6 RIU (estimated)	N/A
		Coaxial nanoring aperture array: ring aperture – 7 nm; inner diameter – 710 nm; array period – 720 nm; thickness of Au – 80 nm (2018) [99]	Silk protein: absorbance peaks – 1650 and 1546 cm−1	Zeroth-order FP resonance: near infrared regime	N/A	IR absorption enhancement: 104 ∼ 105
	Ag	Nanohole array: hole diameter – 175 nm; array period – 450 nm; thickness of Au – 100 nm (2019) [92]	Cy-5 dye molecules; Excitation wavelength: 628 nm	EOT effect: long-wavelength portion in visible regime	N/A	LOD: Attogram ~ single molecule counting sensors
	Al	Nano bowtie aperture: outline - 450 nm; gap – 30 nm; thickness of Al – 170 nm (2012) [78]	Alexa Fluor 647 molecules; Excitation wavelength: 632.8 nm	Modes coupling of dipolar moments from two arms of the bowtie aperture; visible to near infrared regimes	N/A	Fluorescence enhancement: ~ 12 fold
Graphene		Graphene on 50 nm Au (2015) [132]	24-mer ssDNA (7.3 kDa)	Propagating SPP: 785 nm	Phase interrogation; LOD: ~10−9 RIU	N/A
		Ribbon array on gold substrate: 80 nm width (2016) [129]	polyethylene oxide (PED)	Graphene plasmonic resonance: mid-infrared	N/A	Infrared absorption enhancement: ~ 20 fold