Table 2.

Comparison of technical performance of the reviewed EIS-based sensors for diagnosis of COVID-19.

Electrode Type	Working Electrode	Sample Volume	Response Time	Analyte	Capture Element	Linear Range	Detection Limit	Real Sample	Reference
Fully integrated	Carbon + AuNP	5 $\mathsf{\mu }$L	–	RBD protein	Aptamer	1 × 10${}^{-11}$–25 × 10${}^{-9}$ M (5.08 × 10${}^{-10}$–1.27 × 10${}^{-12}$ g/mL)	1.30 × 10${}^{-12}$ M (66 pg/mL)	–	[48]
Fully Integrated	Au + rGO flakes	30 $\mathsf{\mu }$L	15 s	S1 protein Ab RBD protein Ab	S1 protein RBD protein	S1: 1 × 10${}^{-15}$– 30 × 10${}^{-9}$ M RBD: 1 × 10${}^{-15}$–20 × 10${}^{-9}$ M	S1: 2.8 × 10${}^{-15}$ M RBD: 16.9 × 10${}^{-15}$ M	–	[49]
Fully Integrated	Au	15 $\mathsf{\mu }$L	45 min	SARS-CoV-2 pseudo types VSV particle	S1 protein Ab	10${}^4$–10${}^9$ VSV/mL	15 ng/mL (500 pM)	–	[50]
Fully Integrated	Carbon Ink + AuNP	10 $\mathsf{\mu }$L	30 min	S protein Ab	S1 protein	10 × 10${}^{-11}$ to 10 × 10${}^{-7}$	3.16 pM (83.7 pg/mL)	–	[9]
Fully Integrated	Carbon Ink	0.3 $\mathsf{\mu }$L	5 min	S protein	S protein mAb	1–20 fg/mL	1.065 fg/mL	–	[59]
Fully Integrated	Carbon + Graphene + PEDOT:PSS	50 $\mathsf{\mu }$L	30 min	N protein	N protein Ab	1–10,000 pg/mL	116 fg/mL	Nasopharyngeal swab	[71]
Fully Integrated	Carbon Ink	4 $\mathsf{\mu }$L	2 min	S protein	ACE2	10 fg/mL–100 ng/mL	2.18 fg/mL	Saliva, Oropharyngeal and Nasopharyngeal swabs	[70]
Fully Integrated (Dropsens)	Au	50 $\mathsf{\mu }$L	15 min	RBD protein S protein Lysed COVID-19 particles	Targeting peptide	102–103 copies/mL	0.01 copies/mL	Nasopharyngeal swabs	[61]
Fully Integrated (Dropsens)	Au	10 $\mathsf{\mu }$L	45 min	S protein	ACE2 receptor CD147 receptor	ACE2: 700–7000 ng/mL CD147: 500 ng–5000 ng/mL	ACE2: 299.30 ng/mL CD147: 38.99 ng/mL	Oropharyngeal and Nasopharyngeal swabs	[62]
Fully Integrated (Dropsens)	Au	50 $\mathsf{\mu }$L	2 min	SARS-CoV-2	Molecularly-imprinted polymer	3.0–7.0 log10 PFU/mL	4.9 log10 pfu/mL	Saliva	[53]
Fully Integrated (Gamry)	Carbon + CNT + Tungsten Trioxide	5 $\mathsf{\mu }$L in 2.95 mL PBS	3 min	Whole Virus - Human-obtained sample, grown in cell line	Virus-imprinted monomer (3-aminophenol)	Up to 320 pg/mL tested	57 pg/mL	Nasopharyngeal swabs	[54]
Fully integrated (Paper, wax printed)	Carbon Graphene ink	10 $\mathsf{\mu }$L	5 min	RBD Protein	S1 IgG Ab	0.25 fg/mL–1 ng/mL	0.25 fg/mL	Nasopharyngeal swabs	[52]
Fully Integrated (Paper)	Carbon + Zinc-Oxide Nanowires	3 $\mathsf{\mu }$L	15 min	S1 protein Ab	N protein	Tested: 10 × 10${}^{-9}$–1 × 10${}^{-6}$ g/mL	0.4 pg/mL	Serum	[56]
Interdigitated	Au + Carboxylmethylchitosan	Immersion	10 min	S protein Real samples	anti-S protein Ab	Protein: × 10${}^{-20}$– × 10${}^{-8}$ g/mL Real Sample: 7 × 10${}^{-3}$–7 × 10${}^5$ PFU/mL	0.179 fg/mL	Isolated real virus	[66]
Interdigitated	PEDOT:PSS	Aerosol	5 min	S protein	Antibody	–	7 pfu/mL, 350 pfu/mL (air)	Aerosolized porcine transmissible gastroenteritis virus	[69]
Interdigitated	Au + diamond nanopowder	20 $\mathsf{\mu }$L	5 min	N protein	N protein aptamer	1 × 10${}^{-15}$–1 × 10${}^{-10}$ M	0.389 fM	–	[67]
Single Electrode	Tin-doped indium oxide + polypyrrole + AuNP	2 $\mathsf{\mu }$L	15 min	SARS-CoV-2 Nucleocapsid Gene	Amino-modified primer	800–4000 copies/$\mathsf{\mu }$L	258.01 copies/$\mathsf{\mu }$L	Nasopharyngeal	[51]
Working Only	Carbon (Pyrolyzed Graphitic Paper)	6 $\mathsf{\mu }$L	30 min	COVID-19 Ab	S protein	–	–	–	[58]
Working Only	Carbon + AuNP	10 $\mathsf{\mu }$L	40 min	N protein	N protein murine Ab	0.1–100 ng/mL	6 pg/mL	Saliva	[64]
Working Only	Glassy Carbon + rGO	10 $\mathsf{\mu }$L	–	RBD protein	S1 protein Ab	0.16–40 $\mathsf{\mu }$g/mL	150 ng/mL	Saliva	[65]
Working Only	Graphene powder in ethyl cellulose (custom ink)	15 $\mathsf{\mu }$L	30 min	RBD protein S1 protein	S protein (Rabbit PAb)	1–1000 ng/mL	22.91 ± 4.72 pg/mL (RBD) 110.38 ± 9.00 pg/mL (S1)	–	[60]
Working Only	Thin-Film Au Electrode	–	15 min	S1 protein	Aptamer	Not tested	Positive/negative only (80 ng/mL), n = 8	Nasopharyngeal and Oropharyngeal swabs	[55]
Working Only	Steel Mesh + PEDOT-AuNP	Immersion	30 min	SARS-CoV-2 Ab	Truncated	20 × 10${}^{-3}$–2.5 × 10${}^{-3}$ dilutions	–	Serum	[57]
Well-plate	Au	50 $\mathsf{\mu }$L	None	SARS-CoV-2 antibody	RBD protein	0.1, 1.0, 10 mg/mL standards tested	–	–	[68]