Table 1.
Typical examples of different types of CHs.
| Types of CHs | Characteristics | Conductive Components | Materials | Conductive Hydrogel Polymer/System | Applications | Year | Refs |
|---|---|---|---|---|---|---|---|
| Electron-CHs (E-CHs) |
Highly stretchable Better conductivity Better biocompatibility |
Metallic nanoparticles | Ag | Polyacrylic acid (PAA) | Nanoelectronic devices Artificial muscles |
2014 | [16] |
| Polyethylene glycol diacrylate (PEGDA) | Tissue engineering Chemistry reactions ware |
2016 | [17] | ||||
| Au | Poly(acrylamide) [poly (AAm)] and poly(N-isopropyl-acrylamide) [poly (NIPAAm)] | Chemoresistors Biosensors |
2010 | [18] | |||
| Gelatin methacrylate (GelMA) | Cardiac tissue engineering | 2016 | [19] | ||||
| Cu | Polyacrylamide grafted poly(vinyl alcohol) (PAM-g-PVA) | Biosensors Drug delivery system |
2008 | [20] | |||
| Carbon-based materials | CNTs (carbon nanotubes) | Gelatin-grafted-dopamine (GT-DA) Chitosan (CS) |
Multifunctional bioactive dressings | 2019 | [21] | ||
| N-isopropyl acrylamide (NIPAM) | Wearable electronics | 2019 | [22] | ||||
| Grphene /GO/rGO |
Methacryloyl-substituted tropoelastin (MeTro) | Promising different biomedical applications |
2016 | [23] | |||
| Poly(N-isopropylacrylamide) (PNIPAM) | Wearable electronics | 2014 | [24] | ||||
| Conducting polymers | Polyaniline (PANI) | Chitosan-graft-aniline tetramer (CS-AT) Dibenzaldehyde-terminated poly (ethylene glycol) (PEG-DA) |
Drug delivery system | 2016 | [25] | ||
| Poly(N-isopropylacrylamide) (PNIPAM) | Strain sensors Wearable electronics |
2018 | [26] | ||||
| Polypyrrole (PPy) | Polydopamine (PDA) | Wound dressing Biosensors |
2018 | [27] | |||
| PEDOT: PSS | Iota-carrageenan (CRG) Polyvinyl alcohol (PVA) |
Biomedical engineering Biomedical devices |
2019 | [28] | |||
| Hybrid | Pt+ polyaniline |
Pt nanoparticle (PtNP) Polyaniline (PANI) |
Biosensors Biomedical devices |
2015 | [29] | ||
| SWCNTs+ polyaniline |
Single-walled CNTs (SWCNTs) Polyaniline (PANI) |
Supercapacitor Wearable electronics |
2018 | [30] | |||
| Ion-CHs (I-CHs) |
Highly stretchable Conductive Biocompatible Transparency Generate ionic gradients |
Acids | H2SO4 | Polyvinyl alcohol (PVA)-H2SO4 hydrogel Polyaniline (PANI) |
Supercapacitor | 2018 | [31] |
| H3PO4 | Vinyl hybrid silica nanoparticles (VSNPs) Polyacrylamide (PAM) |
Supercapacitor | 2017 | [32] | |||
| Metallic salts | LiCl | Lithium chloride (LiCl) Acrylamide (AAm) |
Soft actuators Electronic fish |
2017 | [33] | ||
| Na+ | Polyacrylamide (PAAm) Sodium chloride (NaCl) |
Epidermal strain sensor Biosensors |
2018 | [34] | |||
| Ca2+ | Polyacrylamide-alginate (PAAm–alginate) Calcium chloride (CaCl2) |
Stretchable ionic touch sensor |
2018 | [35] | |||
| Al3+ | Cellular-structured nanofibrous hydrogels (NFHs) Alginate |
Biomedical engineering Biomedical devices |
2017 | [36] | |||
| Fe3+ | Polyethylene glycol/poly(acrylic acid) (PEG/PAA) double network hydrogel |
Electronic skin Wearable electronics |
2018 | [37] | |||
| K+ | Polyacrylamide (PAAm)/carrageenan double network hydrogel | Thermistor | 2018 | [38] | |||
| Ionic liquids | 1-Ethyl-3-methylimidazolium chloride | Supercapacitor | 2014 | [39] | |||
| E-CHs and I-CHs | Highly stretchable Conductive Biocompatible Transparent/ semitransparent |
Electron conductive components and ions |
H2SO4+ PEDOT |
PEDOT: PSS H2SO4 |
Wearable energy-storage devices | 2017 | [40] |
| Na+ + Ca2++ SWCNTs |
Single-wall carbon nanotubes (SWCNTs) Sodium alginate Calcium chloride (CaCl2) |
Wearable pressure sensor | 2015 | [41] | |||
| Fe3+ + rGO | Poly(acrylic acid) (PAA) Polydopamine (PDA) Iron chloride (FeCl3) |
Electronic skins Biosensors Tissue engineering |
2018 | [42] | |||
| CuPcTs+ Polypyrrole |
Crystal molecular copper-phthalocyanine-3,4′,4″,4‴-tetrasulfonic acid tetrasodium salt (CuPcTs)Polypyrrole(PPy) |
Biomedical devices Biosensors |
2015 | [43] | |||