Fig. 1
From: Recent advances in 3D printable conductive hydrogel inks for neural engineering
Illustration of various conductive hydrogel fabrication strategies by the addition of conductive materials. a Addition of metal nanoparticles using in situ metal ion reduction. Reproduced with permission from [45], copyright Elsevier, 2016. b Gold nanorod (GNR) addition using surface coating. Gelatin methacryloyl (GelMA)-coated GNR (G-GNR) has a colloidal stability and can be added to a photocurable GelMA solution. Reproduced with permission from [41], copyright John Wiley and Sons, 2017. c Addition of multi-walled CNT (MWCNT) by using surface-functionalized CNT. Polydopamine (PDA)-coated MWCNT is soluble and mixable with photocurable poly(citrate-maleic)-ε-polylysine (PME) and poly(ethylene glycol) diacrylate (PEGDA) solution. In addition, PDA coated MWCNT can be stabilized with the addition of PME. Reproduced with permission from [58], copyright Elsevier, 2022. d Conductive hydrogel fabrication using GO. GO can be mixed with a precursor solution and dispersed in a polyacrylamide (PAAm) hydrogel network. Reduction can be achieved after crosslinking to improve the conductivity. Reproduced with permission from [57], copyright Elsevier, 2017. e Conductive polymer addition using in situ monomer polymerization. The aniline monomer can be mixed with a glycyrrhizic acid (GL) solution, and ammonium persulfate (APS) causes the in-situ generation of conductive PANI in a hydrogel matrix through aniline polymerization. Reproduced with permission from [76], copyright American Chemical Society, 2022. f Direct addition of the conductive polymer to the precursor solution. PEDOT:PSS can be dispersed in aqueous solution and easily mixed with photocurable GelMA solution. Reproduced with permission from [78], copyright American Chemical Society, 2018