Table 1.

Summary of electrodes for measuring EOG signals.

Electrode Type	Conductive Material	Supporting Substrate	Biopotential	Biocompatibility	Stretchability	Bendability	Fabrication	Size	Modulus	Advantage	Refs.
Polymer	CNT	PDMS	EOG, EEG	O	O	O	Mix and curing	20 × 5 × 5 mm3	Elasticity 4 MPa	Less changes in electrical resistance against mechanical deformation -High signal-to-noise ratio	[5]
	Ni/Cu	Urethane foam	EOG, EEG	O	X	X	Assembling Metal and foam	14 × 8 × 8 mm3	Compression set 5%	Low interference from skin-electrode interface	[38,84]
	Ag/AgCl	Parylene	EOG, EEG, EMG	O	X	O	Microfabrication process	10 × 10 × 0.05 mm3	-	Ease of thickness control, ultrathin fabrication Well-fitting skin topology	[100]
	Graphene	PDMS	EOG	O	50%	O	APCVD and Coating	6 × 20 mm2	-	Ultrathin, ultrasoft, transparent, and breathable. Angular resolution of 4° of eye movement	[11]
Fiber	Graphene	Cotton textile fabrics	EOG	O	X	O	Simple pad-dry technique	35 × 20 mm2	-	Simple and scalable production method	[104]
	Graphene	Textile fabrics	EOG	O	O	O	Dipping and thermal treatment	30 × 30 mm2	-	Possibility and adaptability for mass manufacturing	[42,57,96]
	Silver	Textile fabrics	EOG, EMG	O	X	O	Embroidering	20 × 20 mm2	-	Comfortableness and the usability with the measurement head cap	[89]
	CEF	CEF fibers	EOG, ECG	O	258.12%	O	Industrial knitting machine	20 × 20 mm2	Stress 11.99 MPa	Flexible, breathable, and washable dry textile electrodes Unrestricted daily activities	[90]
	Silver polymer	Escalade Fabric	EOG, EMG	O	O	O	Screen and Stencil printing	12 × 12 × 1 mm3	-	Textile compatible, relatively low cost for a production lineSmaller scale manufacturing	[105,106]
	Copper	Omniphobic paper	EOG, ECG, EMG	O	58%	O	Razor printer	20 × 15 mm2	Stress 2.5 MPa	Simple, inexpensive, scalable, and fabrication Breathable Ag/AgCl-based EPEDs	[99]
	silver/polyamide	Fabric	EOG	O	O	O	Mix and coating	10 × 10 mm2	-	Reduction in noise by appropriate contact	[40]
Hydrogel	PEGDA/AAm	-	EOG, EEG	O	2500%	O	PμSL-based 3D printer	15 × 15 mm2	-	Excellent stability and ultra-stretchability	[98]
	Starch	Sodium chloride	EOG	O	790%	O	Gelation process	30 × 10 mm2	4.4 kPa	Adhesion, low modulus, and stretchability No need for crosslinker or high pressure/temperature	[61]
	HPC/PVA	PDMS	EOG	O	20%	O	Coating	30 × 10 mm2	286 kPa	Well-adhered to the dimpled epidermis	[97]
	MXene	Polyimide	EOG, EEG, ECG	O	O	O	Mix and Sonicating	20 × 20 mm2	-	Low contact impedances and excellent flexibility	[107]
	PDMS-CB	-	EOG	O	O	O	Mix and deposition	15 × 15 mm2	2 MPa	Continuous, long-term, stable EOG signal recording	[108]
Metal	Silver	Polyimide	EOG	O	100%	O	Microfabrication process	10 × 10 mm2	-	Highly stretchable, skin-like, and biopotential electrodes	[30]
	Gold	Polyimide	EOG	O	30%	O	Microfabrication process	15 × 10 mm2	78 GPa	Comfortable, easy-to-use, and wireless control	[1]