Table 1.

Properties of Different Technologies for Fabricating Flexible Electronics

Technology	Fabrication	Components	Young's Modulus	Resistivity/Conductivity	References
Stretchable conductive polymers	Electropolymerization	Various polymers such as polypyrrole, polyaniline. and poly(3,4-ethylenedioxythiophene)	Giga pascal range; however, thin layers allow for flexibility.	~10−1-10−3 Ωcm	(McCoul et al., 2016, Valentová and Stejskal, 2010, Bloor et al., 1986, Qu et al., 2016)
Doping elastomers	Mixture of conducting or semiconducting elements within an elastomer such as polydimethylsiloxane (PDMS) or polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) and subsequent definition for example by photolithography	Elastomer and conductive or semi-conductive elements	Depending on the elastomer, its thickness, and the dopant.	Depends on the choice of dopant and its concentration.	(Park et al., 2016, Xu et al., 2017, Wang et al., 2018)
Conductive hydrogel-based electrodes by photolithography	Mixture of the ionic (4-(3-butyl-1-imidazolio)-1-butanesulfonic acid trifate) with the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and subsequent photolithography	A hydrogel of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)	~30 kPa	~0.02 Ωcm	(Liu et al., 2019)
Buckled metal conductors	Deposition on a pre-stretched elastomer and release of the strain	Metal conductor and elastomer substrate	Depending on the thickness of the elastomer substrate	−10−6 Ωcm depending on the choice of metal.	(Jones et al., 2004, Lacour et al., 2004)
Localized bonding to pre-stretched elastomer	Microfabrication using photolithography and thin film metal deposition and concomitant release and transfer to a pre-stretched elastomer with predefined bonding sites	Primarily polyimide or SU-8 and a metal conductor on top of an elastomer	Varies depending on thickness of the device ranging from kilo to giga pascals.	−10−6 Ωcm depending on the choice of conductor.	(Xu et al., 2015)
Stretchable architecture	Microfabrication using photolithography and thin film metal deposition	Substrate such as polyimide or SU-8 and a metal conductor	Varies depending on thickness of the device ranging from kilo to giga pascals.	−10−6 Ωcm depending on the choice of conductor.	(Feiner et al., 2019, Fu et al., 2016, Gonzalez et al., 2009, Kim et al., 2011, Xie et al., 2015, Zhou et al., 2017, 2)
Ultra-thin electronics	Microfabrication using photolithography and thin film metal deposition	Substrate such as polyimide or SU-8 and a metal conductor	Varies depending on thickness of the device ranging from kilo to giga pascals.	−10−6 Ωcm depending on the choice of conductor	(Fu et al., 2016, Yang et al., 2019)